Examination, Diagnosis, Prognosis and Management of Downer Cows

Examination, diagnosis, prognosis and management

of downer cows

Phillip John Poulton BVSc (Hons)

Submitted for PhD

July 2015

Faculty of Veterinary and Agriculture Sciences

The University of Melbourne

Produced on archival quality paper

Abstract Downer cows, defined as bright and alert cows that have been recumbent for more than one day, occur commonly in the dairy industry. There are a large variety of causes and their management is complex. This study was designed to investigate various aspects of downer cows under farm conditions in South Gippsland, Victoria, Australia with the aim of improving the understanding of their management. Factors considered were: examination; diagnosis; prognosis; secondary damage; nursing care; euthanasia; grading of sciatic and femoral neuropathies; and the neurology of calving paralysis. Prevention and treatment strategies were not part of this study.

Down cows were observed during the course of their recumbency whilst they were being managed by farmers under commercial dairy farming conditions. Records were collected on the cause of their primary recumbency, the occurrence of any secondary damage, the conditions under which they were cared and their fate. It was the farmers’ choice as to the length of time they continued to nurse their down cow unless I, as the researcher, deemed the cow to be suffering.

Over two hundred cows were investigated in an observational study and there was a representative range of primary causes for their recumbency. Secondary damage occurred very commonly and for most cows the secondary damage was more influential on their outcome than the primary cause of the recumbency.

The level of nursing care was often sub-optimal and there was a strong linear trend of increased recovery with increased level of care. This was directly due to giving cows a higher chance of recovery from the primary cause of their recumbency and indirectly from decreased chance of suffering clinically important secondary damage with improved chance of recovery from such damage, if it occurred. Recommendations for the best way to nurse recumbent cows under southern Australian conditions were proposed.

Protocols for conducting a complete musculo-skeletal examination for recumbent cows were developed during the study enabling more accurate diagnoses to be reached. New ways of classifying sciatic and femoral neuropathies were proposed with grades describing clinical presentation, degree of severity and chance of recovery. The sciatic nerve was the most commonly affected nerve in cows with calving paralysis, often with concurrent

obturator and/or femoral nerve damage and the femoral nerve was found to be the main neuropathy in four of the cows. Calving paralysis cases had a wide variety of clinical presentations.

Some of the concepts developed in this study need further investigation for validation.

Findings from this research will lead to better management of downer cows through: improved examination techniques and more accurate diagnosis of musculo-skeletal syndromes; increased awareness of the importance of secondary damage; emphasising the influence of nursing care on recovery and on the occurrence of secondary damage; improved ability to determine the severity of sciatic and femoral neuropathies; and by encouraging prompt euthanasia of cows that cannot be nursed with a high level of care or deemed to have a poor prognosis. This suite of measures will help improve the welfare of recumbent cows.

Declaration

This is to certify that

(i) the thesis comprises only my original work towards the PhD, except where indicated in the Preface;

(ii) due acknowledgement has been made in the text to all other material used;

(iii) the thesis is less than 100,000 words in length, exclusive of tables, figures, bibliographies and appendices.

Signed,

Phillip John Poulton

July 2015

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Preface This preface is to give credit to those who have contributed to work within this thesis and acknowledge their contribution to my PhD research.

The research project started as a three year part time Masters by Research. This was funded by Dairy Australia (Project TIG 159A). No further funding was obtained when the Masters was converted to a PhD.

Emeritus Professor Ron Slocombe, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, examined and described the histological findings of the sections from the seven cows that I conducted post mortem studies on. He oversaw my descriptions in the pathology sections of the thesis.

Some statistical analyses were performed by Mr Garry Anderson, biometrician, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne. I collected the data, entered and analysed some of it using WinPepi under the close supervision of Mr. Garry Anderson. He further analysed some of the data with StratXact, following which I documented and interpreted all results as they appear in the thesis. Advice on choice of statistical tests and methodology was provided by Mr. Anderson.

The Examination data collection sheets were designed by Ms. Dianne Rees, Research Assistant, Ruminant Group, Faculty Veterinary and Agricultural Sciences, The University of Melbourne.

Acknowledgements This project is the fulfilment of more than 25 years of my interest in down cows whilst working in clinical practice as a dairy cattle veterinarian. Associate Professor Michael Pyman, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, was instrumental in convincing me to enrol in a Masters in Veterinary Science to validate the concepts for downer cows that I had developed over the years. The project started as research into the importance of secondary damage in recumbent cattle and the influence of nursing care. This involved taking leave-of-absence from my private practice for two three- month periods during the seasonal winter calving periods in 2011 and 2012.

The amount of information gathered during the research period allowed me to explore other aspects of recumbency in dairy cows and the project was expanded into a PhD. Michael has been my supervisor for the full journey and I would like to thank him for his help, encouragement, guidance, editing and friendship during this time. It would not have occurred without his efforts.

I have been extremely fortunate to have had fantastic back up and support from all of the members of my committee. They have given me a tremendous amount of help along the journey, have always gone out of their way to make my work easier and have enriched my thesis with their various suggestions.

My original committee supervisor was Prof. Andrew Vizard. Andrew had the ability to focus attention on the important findings of my studies, which sometimes seemed to be lost among the large amount of data. Thank you for your clear, concise logic. Andrew retired at the end of 2013 and his role of Chairman was taken over by Prof. Ted Whittem. Thank you Ted, for your input.

I would like to extend my thanks to Mr. Garry Anderson, biometrician. My statistical knowledge was basic, at best, when I started this project and I relied very heavily on Garry’s expertise. Garry also retired at the end of 2013 but I was fortunate enough that he continued the role in his own time. Garry’s professionalism and acute eye for detail was tremendously valuable to me. I really appreciate his efforts for the statistical component and also for his help with general editing of the thesis. With its completion he will have more time for golf and his other retirement activities. An enormous thank- you.

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Emeritus Professor Ron Slocombe provided assistance for the post mortem studies and described the histological findings that are contained in two chapters. He has helped edit these chapters, which we expect to submit as journal articles in the future. His input and expertise was greatly appreciated, especially as he continued his role in his own time after he also retired at the end of 2013.

Associate Professor Peter Mansell was another valued member of my committee, contributing general advice as required, and in particular editing my Literature Review.

Professor Andrew Fisher contributed to my steering group in an overseeing and structural role. His knowledge of scientific writing helped me change from my ‘conversational’ style.

I would like to acknowledge the opportunity and funding provided by Dairy Australia, which initiated this research. Dr. Robin Condron, Manager Risk Analysis, Dairy Australia, was the initial driver from Dairy Australia as they were concerned at the animal welfare aspects of recumbent cattle. Dairy Australia required practical research to be undertaken to develop industry guidelines for the management of down cows. This information is now available for stakeholders of the dairy industry and represents ‘best practice’ management. Thanks to Dr. Kathryn Davis, Program Manager, Animal Health and Fertility, Dairy Australia, who took over the role started by Dr. Condron.

I would like to thank the farmers of South Gippsland for their cooperation during the research phase of my project. All of the data was collected on commercial dairy farms during their daily work cycles. They allowed me access to their cows and machinery, which enabled me to gather the large amount of data needed for the study.

Many of the cows were initially attended by veterinarians from my clinic, the Tarwin Veterinary Group. Thanks go to them for their cooperation in referring suitable cows. Thank you to my fellow directors for agreeing to my leave-of-absence during the busy calving period over the two years of my study.

Lastly, to my partner Lisa, thank you for your patience and understanding during the long periods involved with this project, particularly when it expanded into a PhD. Lisa often accompanied me during the farm visits as my scribe and for a ‘non-farm’ person has excellent knowledge of downer cows. We will now have time to do the things that have been ‘on-hold’ for a while.

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Related publications published during the course of this project

Poulton P.J. 2014, Musculo-skeletal examination and diagnosis of the downer cow. In: Proceedings of 28th World Association of Cattle Buiatrics Congress, Cairns, July 2014

Poulton P.J. 2014, Management of the downer cow. In: Proceedings of 28th World Association of Cattle Buiatrics Congress, Cairns, July, 2014

Poulton PJ. 2013, Musculo-skeletal examination, diagnosis and management of the downer cow. In: Conference Proceedings of British Cattle Veterinary Association Congress, Harrogate, October, 2013

Poulton PJ. 2012, Musculo-skeletal examination and diagnosis of the downer cow. In: Proceedings of the Australian Veterinary Association Conference, Canberra, May, 2012

Poulton PJ. 2012, Treatment and nursing of the downer cow In: Proceedings of the Australian Veterinary Association Conference, Canberra, May, 2012

Poulton PJ. 2011, Musculo-skeletal examination of the downer cow. In: Proceedings of the Australian Cattle Veterinarians Congress, Launceston, April, 2011

Poulton PJ. 2011, Functional anatomy for downer cows. In: Proceedings of the Australian Cattle Veterinarians Congress, Launceston, April, 2011

Two articles have been submitted to the Australian Veterinary Journal and are currently under review (July 2015). They are entitled:

The importance of secondary damage in downer cows

PJ Poulton, AL Vizard, GA Anderson and MF Pyman

High quality care improves outcome in recumbent dairy cattle

PJ Poulton, AL Vizard, GA Anderson and MF Pyman

Table of Contents Table of Contents Abstract ...... i Declaration ...... iii Preface ...... v Acknowledgements ...... vii Related publications published during the course of this project ...... ix Table of Contents ...... xi List of Tables ...... xv List of Figures ...... xv Chapter 1. General Introduction:...... 1 Chapter 2. Literature Review ...... 7 2.1 Introduction ...... 7 2.2 Definition ...... 7 2.3 History ...... 8 2.4 Incidence ...... 9 2.5 Anatomy of the Major Nerves of the Hind and Fore Limb in Cattle ...... 10 2.5.1 Nerves of the hindlimb of cattle ...... 10 2.5.2 Nerves of the forelimb of cattle ...... 12 2.6 Musculo-Skeletal Causes of Recumbency in Cattle ...... 13 2.6.1 Neuropathies ...... 13 2.6.2 Skeletal injuries ...... 18 2.6.3 Soft tissue/muscle injuries ...... 19 2.6.4 Compartment Syndrome ...... 19 2.6.5 Secondary neuropathies ...... 21 2.7 Management of Recumbent Cattle ...... 22 2.7.1 Management Plan ...... 22 2.7.2 Treatment ...... 22 2.7.3 Welfare ...... 23 2.7.4 Euthanasia ...... 24 2.7.5 Nursing ...... 25 Chapter 3. General Materials and Methods ...... 29 3.1 Data Collection ...... 29 3.2 Study design ...... 29 3.3 Ethics ...... 30 3.4 Selection of Cases ...... 30 3.5 Records...... 32 3.6 Examination Techniques ...... 32 3.7 Diagnosis ...... 34 3.7.1 Primary cause of recumbency ...... 34 3.7.2 Traumatic injuries ...... 35 3.7.3 Neuropathies ...... 35 3.7.4 Compartment Syndrome ...... 37 3.7.5 ‘Given up’ ...... 37

3.7.6 Differentiating primary conditions from secondary conditions ...... 37 3.7.7 Secondary damage ...... 38 3.8 Nursing Factors ...... 38 3.8.1 Nursing score ...... 39 3.9 Outcomes ...... 40 3.10 Statistical analysis ...... 41 Chapter 4. Musculo-Skeletal Examination of the Recumbent Cow ...... 45 4.1 Introduction ...... 45 4.2 Proposed Musculo-Skeletal Examination Technique for Down Cows ...... 46 4.2.1 Mechanism of the flexor-withdrawal reflex ...... 50 4.2.2 Mechanism of the patellar reflex ...... 52 4.3 Diagnosis of Neuropathies of Recumbent Cows ...... 52 4.4 Results ...... 56 4.5 Discussion ...... 58 4.6 Conclusions ...... 59 Chapter 5. The Importance of Secondary Damage in Downer Cows ...... 61 5.1 Introduction ...... 61 5.2 Materials and Methods ...... 62 5.2.1 Statistical analysis ...... 67 5.3 Results ...... 67 5.4 Discussion ...... 73 5.5 Conclusions ...... 77 Chapter 6. High Quality Care Improves Outcome in Recumbent Cows ...... 79 6.1 Introduction ...... 79 6.2 Materials and Methods ...... 79 6.2.1 Statistical analysis ...... 85 6.3 Results ...... 85 6.3.1 Secondary damage ...... 89 6.4 Discussion ...... 91 6.4.1 Limitations of the study ...... 96 6.5 Conclusions ...... 97 Chapter 7. Management of Bilateral Femoral Nerve Injuries in Cows ...... 99 7.1 Introduction ...... 99 7.2 Materials and Methods ...... 100 7.2.2 Statistical analysis ...... 106 7.3 Results ...... 106 7.4 Discussion ...... 112 7.5 Conclusion ...... 117 Chapter 8. Classification and Grading of L6-S2 Nerve Plexus Damage ...... 119 8.1 Introduction ...... 119 8.2 Materials and Methods ...... 122 8.2.1 Statistical analysis ...... 127 8.3 Results ...... 128 8.3.1 Post mortem findings ...... 137 8.4 Discussion ...... 142

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8.4.1 Grading of damage to the L6-S2 nerve plexus ...... 142 8.4.2 Prognosis of grades ...... 147 8.5 Conclusions ...... 153 Chapter 9. Calving Paralysis ...... 155 9.1 Introduction ...... 155 9.2 Materials and Methods ...... 159 9.2.1 Statistical analysis ...... 159 9.3 Results ...... 160 9.4 Discussion ...... 162 9.5 Conclusions ...... 163 Chapter 10. Conclusions ...... 165 10.1 Summary of Chapter Findings ...... 165 10.1.1 Chapter 4: Musculo-skeletal examination of the recumbent cow ...... 165 10.1.2 Chapter 5: The importance of secondary damage in downer cows ...... 165 10.1.3 Chapter 6: High quality care improves outcome in recumbent cows ...... 166 10.1.4 Chapter 7: Management of bilateral femoral nerve injuries in cows ...... 167 10.1.5 Chapter 8: Classification and grading of L6-S2 nerve plexus damage ...... 168 10.1.6 Chapter 9: Calving paralysis ...... 168 10.2 Future Studies ...... 169 10.3 Final Conclusions for Research Questions ...... 170 10.4 Final Statement ...... 172 Chapter 11. Bibliography ...... 173 Chapter 12. Appendices ...... 177 12.1 Appendix 1: Hindlimb Anatomy ...... 177 12.1.1 Lumbar plexus ...... 177 12.1.2 Sacral plexus ...... 178 12.2 Appendix 2: Examination Sheet ...... 181

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List of Tables Table 2.1. Critical CK levels relative to days down when sampled (Clark et al., 1987) ...... 20 Table 3.1. Proposed optimum standard of care for recumbent cows in southern Victorian dairying areas ...... 42 Table 3.2. Criteria of the nursing scores used to assess compliance to the proposed optimum nursing standards for recumbent cows in Southern Victoria ...... 43 Table 4.1. Secondary damage diagnosed in 218 downer cows by the examination technique proposed in the study compared to likely diagnoses if the cows were not lifted and patellar reflexes were not performed (abbreviated technique) ...... 57 Table 5.1. Critical CK levels relative to days recumbent in downer cows ...... 64 Table 5.2. Primary cause of recumbency, day 7 and final recovery of 218 downer cows ...... 67 Table 5.3. Results of univariable logistic regression analysis for still being recumbent (case) by day 7 for 218 downer cows by primary cause ...... 68 Table 5.4. Day 7 progress of 218 downer cows ...... 68 Table 5.5. Results of univariable logistic regression analysis assessing risk factors for still being recumbent (case) by day 7 for 218 downer cows...... 72 Table 6.1. Optimum standard of nursing care for recumbent cows in southern Victorian dairying areas ...... 83 Table 6.2. Criteria of the four nursing scores used in this study ...... 84 Table 6.3. Day 7 recovery by nursing scores for the three nursing periods for 218 downer cows ...... 86 Table 6.4. Final recovery by nursing scores for the three nursing periods for 218 downer cows ...... 86 Table 6.5. Final recovery of the 46 cows nursed for longer than seven days by nursing score for the subsequent and overall nursing periods ...... 89 Table 6.6. Relationship between the occurrence of clinically important secondary damage and nursing scores for the three nursing periods in 218 downer cows ...... 90 Table 6.7. Occurrence of subsequent clinically important secondary damage and the two combined nursing scores in 186 downer cows ...... 91 Table 7.1. Description of the four grades of femoral neuropathy in recumbent cows ...... 102 Table 7.2. Optimum care for cows with femoral neuropathies ...... 104 Table 7.3. Criteria of the four nursing scores used to describe compliance to optimum level of care for the relevant femoral grade ...... 105 Table 7.4. Day 7 and final recovery of 50 cows with bilateral femoral nerve damage ...... 107 Table 7.5. Number of days to outcome for ‘worst’ Grade 1 femoral nerve injury in 19 cows ...... 108 Table 7.6. Number of days to outcome for ‘worst’ Grade 2 femoral injury in 16 cows ...... 108 Table 7.7. Number of days to outcome for ‘worst’ Grade 3 femoral injury in 13 cows ...... 108 Table 7.8. Outcome of ‘worst’ femoral grade by nursing score for 50 cows ...... 109 Table 7.9. Outcome of initial femoral grade by nursing score for 50 cows ...... 110 Table 7.10. Cause of death for the 25 cows that did not recover ...... 110 Table 8.1. Codes for the different presentations of damage to the branches of the L6-S2 plexus as proposed by this thesis ...... 126 Table 8.2. Occurrence of the different presentations of L6-S2 damage with or without concurrent incidental obturator and/or femoral nerve damage or tibial paresis in 103 cows ...... 129 Table 8.3. Day 7 recovery of 103 cows with L6-S2 plexus damage with or without obturator nerve damage, with or without femoral nerve damage and with or without tibial paresis ...... 130

Table 8.4. Day 3, 7,final recovery, occurrence of clinically important secondary damage and secondary dislocated hip for 103 cows with various grades of L6-S2 plexus damage irrespective of concurrent femoral or obturator nerve damage or tibial paresis ...... 131 Table 8.5. Day 3, 7 and final recovery for 26 cows with various grades of L6-S2 plexus damage irrespective of concurrent femoral or obturator nerve damage or tibial paresis that did not suffer any clinically important secondary damage ...... 131 Table 8.6. Day 3, 7 and final recovery for 75 cows with various grades of L6-S2 plexus damage irrespective of concurrent femoral or obturator nerve damage or tibial paresis that were nursed overall at a satisfactory level ...... 132 Table 8.7. Weight bearing ability of the weaker hindlimb when first lifted for 95 cows with L6-S2 injury according to their L6-S2 grade ...... 133 Table 8.8. Weight bearing ability of the weaker hindlimb when lifted at first visit differentiated into at least 75% or less than 75% and recovery by day 3, 7 and final for the 95 cows with L6-S2 injury that were lifted ...... 134 Table 8.9. L6-S2 grades allocated into three groups of severity based on statistical and clinical judgement ...... 134 Table 8.10. Day 3, 7 and final recovery for the 103 cows with damage to the L6-S2 plexus and for those 75 cows that were nursed satisfactorily and weight bearing ability of the weaker hindlimb on the first visits for the three statistically based prognostic groups ...... 135 Table 8.11. Day 3, 7 and final recovery for the 103 cows with damage to the L6-S2 plexus and for those 75 cows that were nursed satisfactorily and weight bearing ability of the weaker hindlimb on the first visits for the three clinically based prognostic groups ...... 136 Table 8.12. Risk of secondary hip dislocation with grade of L6-S2 plexus damage in 103 cows ...... 137 Table 9.1. Clinical presentation of 104 cows recumbent with calving paralysis ...... 160 Table 9.2. Susceptibility of cows to secondary hip dislocation if the obturator or femoral nerve was part of the neuropathy in 104 cows recumbent with calving paralysis ...... 161

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List of Figures Figure 4.1. Major nerve branches of L6-S2 nerve plexus, adapted from Smith-Maxie (1997) ...... 49 Figure 4.2. Sensory distribution of forelimb nerves in cattle, adapted from Smith-Maxie (1997) ...... 49 Figure 5.1. Cumulative daily loss and recovery percentages for 218 downer cows ...... 69 Figure 6.1. Daily cumulative recovery percentage by overall nursing score for 218 downer cows ..... 87 Figure 6.2. Daily cumulative death percentage by overall nursing score for 218 downer cows ...... 87 Figure 6.3. Daily cumulative recovery of 151 cows nursed satisfactorily compared to 67 cows nursed unsatisfactorily ...... 88 Figure 7.1. Caudal tendency of hindlimbs in a cow with femoral nerve damage...... 101 Figure 7.2. H&E stained section (bar equals 0.5 mm) of L5 femoral nerve root showing complete lysis and loss of cell nuclei in adipose tissue (right of image)and extensive haemorrhage between cells but the nerve trunk appears unaffected ...... 111 Figure 8.1. Cow 2855 with anterior right hindlimb posture ...... 139 Figure 8.2. Cow 3454 with knuckling of right hindlimb ...... 139 Figure 8.3. Cow Z66 with total paralysis of both hindlimbs ...... 140 Figure 8.4. Cow 2855 showing damage to the right side S1 and S2 ventral branches without damage to L6 ...... 140 Figure 8.5. Cow 3545 showing damage to the right side L6 and S1 ventral branches ...... 141 Figure 8.6. Cow Z66 showing site of damaged L6 root and forceps pointing to left S1 root ...... 141 Figure 8.7. Cow with L6-S2 proximal grade 3 showing abnormal sitting position ...... 152

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Chapter 1: General Introduction

Chapter 1. General Introduction: Recumbency is a state of ‘lying down’ (Forbes et al., 1986). A ‘down’ cow is a cow that is recumbent and unable to stand up unassisted. Some may be able to stand and even walk around after being lifted, but are still unable to stand by themselves.

There are a large number of different reasons for cows to become recumbent and they may be thought of in four categories: metabolic; musculo-skeletal; acute systemic illness; and miscellaneous. Metabolic conditions include: post-parturient hypocalcaemia (milk fever), hypomagnesaemia (grass tetany) and protein-energy deficiency; musculo-skeletal conditions include calving paralysis, sciatic, femoral, obturator, brachial plexus and radial nerve neuropathies, hip dislocation, pelvic fracture, muscle rupture and back injuries; acute systemic illness include severe cases of conditions such as Salmonellosis, grain overload and mastitis. Miscellaneous conditions would include being cast, dystocia and nitrate poising.

A ‘down’ cow must be differentiated from a ‘downer’ cow, which is a vague term and can have different definitions: It has been described as “a cow that is unable or unwilling to stand for a variable period of time; persistent (>12 hours), intractable recumbency being the common thread of such cases” (Van Metre, 2001). It has been described as “a general term that applies to any peri-parturient cow that is in sternal recumbency and is unable to rise, but where the reason for the recumbency is unknown” (Parkinson et al., 2010). It has also been described as “any cow that is down in sternal recumbency for more than 24 hours with no evidence of systemic illness” (Cox, 1981). For the purposes of this thesis, I will use the last definition, such that it covers cows that have been recumbent for more than one day and are bright, alert and responsive. It will include cows where the primary cause was known and is not restricted to any particular stage of lactation. All downer cows are down but only some down cows are downer cows.

Downer cows are a common problem for the Australian dairying industry, as they are in all of the major dairy areas around the world. Most dairy farms would encounter downer cows in most years and the success rate of them is often low, with only 24% of the Australian dairy cows that were recumbent for more than 24 hours surviving (Watson and Watson, 2014) leading to economic losses. The management of downer cows is labour intensive, as they require nursing by stock carers whilst recovering from their condition, which may be for only a day or two but can be for protracted periods, sometimes several weeks.

Chapter 1: General Introduction

The management of recumbent cows raises animal welfare issues from both the individual animal perspective and for the dairy industry as a whole. From an individual animal perspective it is important that cows are not subjected to unnecessary suffering when being nursed during the period of recumbency. From an industry perspective animal welfare is a very important issue in these modern times as the general public does not tolerate suffering of animals engaged in the production of food for humans. Real or perceived cruelty to recumbent cows whilst being nursed is a potential welfare issue for the Australian dairy industry. All stakeholders, from farmers, veterinarians, advisors and industry personnel have a responsibility to ensure that recumbent cattle are managed in an appropriate manner. Guidelines for their acceptable level care need to be available to stakeholders and education programs need to be implemented.

The Australian dairy industry is currently worth $13 billion annually as a farm, manufacturing and export industry. There are 6700 dairy farmers producing around 9.5 billion litres of milk a year with a farm gate value of $4 billion. The industry directly employs 43,000 Australians on farms and in factories and has a regional economic multiplier effect at 2.5. More than 100,000 Australians are indirectly employed in related service industries (Dairy Australia, 2015).

The size of the national dairy herd in 2013/14 was 1.69 million cows with an average herd size of 268 cows. Production is largely pasture based and mainly located in the temperate regions of Australia. Annual industry milk production was 9,239 million litres, with an average annual milk production per cow of 5,471 litres.

The dairy industry is Australia's third largest rural industry and Australia is the world’s third largest dairy exporter industry behind the EU and New Zealand supplying seven per cent of the world dairy trade (Dairy Australia, 2015).

A review of the literature on downer cows revealed low numbers of studies published on this subject and this is disproportional to the level of importance of the problem. Much of the information and knowledge used by farmers and veterinarians when dealing with downer cows is anecdotal or based on previous experience (Huxley et al., 2010). There is a good case for robust research to be undertaken in this area.

Chapter 1: General Introduction

When confronted with a recumbent cow the farmer needs to decide whether to try to manage the cow to give her a chance to recover or to euthanase her. This decision needs to be made immediately and re-assessed at appropriate time intervals, particularly if nursing over a period of days or weeks is involved.

For the farmer to make this initial decision, the cause of the recumbency needs to be known. This may be straightforward as many of the common causes, such as milk fever and calving paralysis, are easily recognised by experienced stock handlers. However there are many different causes of recumbency, some of which are difficult to determine and expert veterinary advice is often required. There are a variety of textbooks to help guide veterinarians examine and diagnose the different causes of recumbency. Diagnosis of the various metabolic and acute systemic disease conditions are well covered in the literature, as are some of the musculo-skeletal conditions. Examining recumbent cattle can be difficult and potentially dangerous due to their size and position (Constable, 2004). This is particularly true when performing neurological examinations on recumbent cows and adjustments away from preferred small animal neurological techniques may be needed (de Lahunta and Glass, 2009). These limitations may compromise the examination technique resulting in reduced accuracy of diagnosis or mean no diagnosis is reached. The ability to consistently perform thorough musculo-skeletal and neurological examinations is a cornerstone of management of recumbent cattle. Improved examination techniques are one aspect covered in this thesis.

Once the diagnosis is known it is important to estimate the chance of recovery before initiating treatment as those with very poor prognoses should be immediately euthanased. Cows recumbent from conditions which would be expected to respond favourably, such as milk fever, would be readily treated. Other conditions, such as calving paralysis and back injuries, may or may not recover depending on their severity. Specific neuropathies, such as sciatic and femoral, are described in the literature but information relating to the chance of recovery from them could not be found. The ability to grade the severity of these conditions would allow better decisions to be made when cows recumbent from them are first attended. Those severely affected would then be more likely to be euthanased promptly rather than nursed for a period of time before ultimately being destroyed. This would be a better animal welfare outcome as it would reduce unnecessary suffering. Grading scales for

Chapter 1: General Introduction sciatic and femoral nerve injuries based on their clinical presentation and outcome are proposed in this thesis.

Once the diagnosis is reached and the decision to proceed with treatment is made the cow needs to be treated appropriately for her condition. This aspect is not covered in this thesis as it is well covered by many other sources. However, the use of non-steroidal anti- inflammatory (NSAID) drugs is mention briefly in Chapter 6.

The other aspect of managing recumbent cows is the nursing care that they require whilst recumbent. The importance of adequate nursing is discussed in a number of references in the literature (Andrews, 1986, Chamberlain, 1987, Huxley et al., 2010) but it is general information only and no documentation of its quantitative importance or its influence on recovery could be found. One aim of the study was to investigate this aspect carefully by recording the different ways recumbent cows were cared for under field conditions in southern Australia, develop a standard of ‘ideal’ nursing requirements and analyse outcome against compliance to these standards. This was undertaken for recumbent cows as an overall group and was also tailored specifically for the different grades of femoral neuropathies. These requirements were designed to give the cows the best chance of recovery from their primary condition.

Implementing these requirements effectively is a demanding task and if this is required over an extended period of time many farmers may decide to euthanase the cow instead. This is also a better welfare outcome than nursing cows in a sub-optimal way, in the hope that they may eventually recover.

Farmers tend to make decisions on treatment versus euthanasia on a cost/benefit basis. Some of the factors contributing to their decision will be cost of treatment and nursing, and likely chance of success. Other factors such as the real or perceived value of the cow, past experiences with nursing recumbent cows and time restraints from other activities are often considered.

Once cows are recumbent, no matter the primary reason, they are susceptible to a variety of secondary conditions, some of which are caused from pressure to the limbs from being recumbent (Cox, 1982). This relationship was poorly understood historically, particularly for milk fever cows that failed to rise after treatment, giving rise to the term ‘downer’ cow. A

Chapter 1: General Introduction

series of reports in the 1980’s (Cox, 1982, Cox, 1988, Cox and Martin, 1975, Cox et al., 1982) highlighted the role of secondary myopathies and neuropathies in recumbent cows. This gave a greater understanding of the syndrome and switched attention away from continuing to treat many of these milk fever cows with more metabolic solutions. But the question of how common and how important these secondary issues are in recumbent cows was not addressed in the literature. The starting hypothesis for this thesis was that “once cows have been recumbent for more than one day from any cause, secondary damage is more influential on their chance of recovery than the primary cause of their recumbency”. If this was proven to be true, the secondary hypothesis was that “the level of nursing care provided to recumbent cows is directly related to recovery and the occurrence of secondary damage”. It was proposed that nursing care influenced the outcome of recumbent cows at two levels: improving their chance of recovery from their primary ailment; and secondarily, by reducing the chance of being affected by clinically important secondary damage, and increasing their chance of recovery from such damage, if it did occur.

Documentation of the importance of providing high quality care to recumbent cows would lead to being able to provide better guidelines to stock carers and advisors. Better educated stock carers are more likely to nurse recumbent cows at a higher standard, which would increase the chance of recovery for recumbent cows and lead to better animal welfare outcomes.

The binding theme of this thesis is to cover the various areas involved with managing cows recumbent from primary musculo-skeletal conditions or that are downer cows, as defined as ‘bright, alert and responsive cows that have been recumbent for more than one day’ (Cox, 1981). It will cover musculo-skeletal examination, diagnosis, prognosis, euthanasia and nursing care.

Chapter 1: General Introduction

The thesis investigated six major questions:

1 How important are the secondary effects of recumbency on the outcome of the cow, compared to the importance of the primary condition?

2 Do nursing factors influence recovery and the occurrence of secondary damage in recumbent cows?

3 Clearly define “best practice” when examining recumbent cows

4 In cases of femoral nerve injury, can a grading system be developed to describe the different clinical presentations and predict the chance of recovery?

5 In cases of sciatic nerve injures, can a grading system be developed to describe the different clinical presentations and predict the chance of recovery?

6 What nerve/s are damaged in cases of calving paralysis and where is the site/s of the damage?

Downer cows are an important issue for the dairy industry from both a production and animal welfare perspective. This thesis aims to improve a number of aspects of downer cow management including: better examination techniques to enhance the diagnosis of musculo-skeletal conditions; research into the importance of secondary damage that can occur once cows have become recumbent from any primary cause; investigate the influence the quality of nursing care has on recovery and occurrence of secondary damage so as to be able to develop robust guidelines for their optimum care; description and grading of sciatic and femoral neuropathies; and detail the types of neuropathies involved with calving paralysis.

Advances in these various issues affecting downer cows should lead to a better understanding of them which should in turn lead to improvements in the management of downer cows. This improved management will result from better nursing of those cows deemed worthy of treatment and thus better recovery, and by the prompt euthanasia of those cows deemed not worthy of treatment due to either severe damage or the inability to provide high level care to them during their convalescence.

Chapter 2: Literature Review

Chapter 2. Literature Review

2.1 Introduction Recumbency in cattle is a world-wide problem. There are a large number of different causes, some of which are musculo-skeletal disorders. Cattle afflicted by recumbency from any cause that fail to rise within an initial period of time are at risk of developing secondary complications from the recumbency, some of which involve damage to the musculo-skeletal system. One group of recumbent cattle are termed ‘downer’ cows, which usually refers to cattle that have been recumbent for more than one day and are bright and alert (Cox, 1981).

This review of the literature focuses on downer cows and recumbency in cattle from musculo-skeletal disorders. It includes the management of these recumbent cows, part of which is their nursing care. It is important to note that there is a dearth of information on the specifics of management of recumbent cattle, in particular their nursing. Much of the information is general in nature, often opinion pieces based on cattle veterinarians’ experience. Such references are not ‘evidence based’, as they lack any hard research-based data. As such, they do not carry much weight when critically analysing the approach to downer cow management.

2.2 Definition Recumbency is a state of ‘lying down’ (Forbes et al., 1986). A ‘down’ cow is a cow that is recumbent and unable to stand up unassisted. Some may be able to stand and even walk after being lifted, but are still unable to stand by themselves.

A ‘down’ cow must be differentiated from a ‘downer’ cow. The terms downer cow or downer cow syndrome can have different definitions: It has been described as “a cow that is unable or unwilling to stand for a variable period of time; persistent (>12 hours), intractable recumbency appears to be the common thread of such cases” (Van Metre, 2001); Or as “a general term that applies to any peri-parturient cow that is in sternal recumbency and is unable to rise, but where the reason for the recumbency is unknown” (Parkinson et al., 2010). It has also been described as “any cow that is down in sternal recumbency for more than 24 hours with no evidence of systemic illness” (Cox, 1981).

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There are several hundred possible diagnoses for a persistently recumbent cow (Van Metre, 2001). I categorise the causes of primary recumbency into four categories: metabolic; musculo-skeletal; acute systemic illness; and miscellaneous. Metabolic conditions include: post-parturient hypocalcaemia (milk fever), hypomagnesaemia (grass tetany) and protein- energy deficiency; musculo-skeletal conditions include calving paralysis, sciatic, femoral, obturator, brachial plexus and radial nerve neuropathies, hip dislocation, pelvic fracture and back injuries; acute systemic illness include severe cases of conditions such as Salmonellosis, grain overload and mastitis. Miscellaneous conditions would include being cast, dystocia and nitrate poising.

2.3 History The concept of the downer cow has changed over the period of time and historically, was often a term used without definition (Cox, 1988). It has been described as a cow not rising within 10 minutes of receiving calcium treatment (Fenwick, 1969) and as a cow that did not rise within 24 hours of treatment with calcium (Jonsson and Pehrson, 1969). Another definition was recumbency for more than 24 hours related to the calving period after the animal had received two calcium injections and for which there was no obvious reason for being down (Andrews, 1983). The general thinking at the time was that the downer cow syndrome was a complication of milk fever. However, a Danish study found only 52% of 43 downer cows studied were associated with milk fever (Flagstad et al., 1970).

Many conditions were associated with downer cow syndrome in the 1970’s, some of which were poorly defined and hard to differentiate. They included: Metabolic Complex Parturient Paresis; hypophosphataemia; hypomagnesaemia; hypokalaemia; hyper- and hypo- adrenocortical activities; cerebral oedema; albuminuria; renal disease; hepatic changes and muscle degeneration and physical injuries (Kronfeld, 1970).

Blood et al (1979) stated that whilst its aetiology was not clear the downer cow syndrome was a complication of milk fever. The cows were unable to get up following treatment for milk fever due to traumatic injury to the leg muscles, which occurred when the cow fell during the early stages of the condition or during parturition. It could also occur if there was a delay (4 hours or more) in the treatment for milk fever, causing an ischaemic myonecrosis of the hind and fore limbs. They doubted the role of factors such as magnesium, calcium,

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phosphorus, corticosteroids, vitamin E and selenium, which had been largely thought of as the cause of the downer cow syndrome to this point in time. Secondary damage was not considered to be the main factor involved in the downer cow syndrome despite emphasis on the importance of adequate bedding and frequent rolling to minimize the effects from prolonged recumbency (Blood et al., 1979).

In a revised edition of the same text book, Radostits (2010) stated the aetiology of downer cow syndrome was an ischaemic necrosis of the large pelvic muscles secondary to the recumbency, most commonly from milk fever (Radostits et al., 2010). Thus, secondary damage was now thought to be the main cause of the downer cow syndrome.

Downer cow syndrome was considered to be due to secondary damage and all recumbent cattle were susceptible to it regardless of the primary cause of their recumbency. Pressure damage occurs to the muscles and nerves of the hind limbs, as shown by the fact that they can usually stand on their front legs if lifted with a suitable device (Cox, 1988).

2.4 Incidence The incidence of downer cows is hard to determine due to the different interpretations of the term. An Australian survey showed that 91% of dairy herds across Australia had had recumbent cows in the previous twelve months, with an average number of 7.7 cows per herd. Approximately one-half of the cows had recovered within the first 24 hours so the average occurrence of downer cows (recumbent for more than 24 hours) was 3.7 cows per herd, varying from 2.0 cows in small herds (<150 cows) to 7.7 cows for extra-large herds (>500 cows). The average number of downer cows that recovered was 0.9 (24%) cows per herd (Watson and Watson, 2014). Unfortunately, the data was collected on a ‘per herd’ basis and whilst it was broken down into ‘small’ (<150 cows), ‘medium’ (150-300 cows), ‘large’ (301-500 cows) and ‘extra-large’ (>500 cows) herd sizes, the incidence of downer cows was not analysed on a ‘per cow’ rate. When the incidence of downer cows among milk fever cases was considered, various studies have quoted rates from 4.5 to 28% (Parkinson et al., 2010). A survey in one study of 2705 lactations in New York State revealed an incidence of 1.1% in the first 30 days post-partum, with the risk increasing five-fold if the cow suffered a dystocia or clinical milk fever (Correa et al., 1993).

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2.5 Anatomy of the Major Nerves of the Hind and Fore Limb in Cattle This section describes the anatomy of the major nerves of the hind and fore limbs in cattle (Getty, 1975). The specific muscles of the hindlimb with their functions and innervations are listed in Appendix 1.

2.5.1 Nerves of the hindlimb of cattle The femoral nerve forms from the ventral branch of the fifth lumbar nerve (L5), with contributions from the fourth (L4) and sixth lumbar (L6) nerves. It gives branches to the psoas and iliacus muscles, which flex the hip and rotate the thigh. The main femoral nerve terminates in the quadriceps femoris muscle, which is a strong extensor of the stifle joint and flexor of the hip. It also innervates the sartorius muscle, which flexes the hip and adducts the limb. Its branch, the saphenous nerve, and the obturator nerve innervate the gracilis and pectineus muscles, which adduct the limb, flex the hip and stifle and extend the hock. The saphenous nerve continues along the medial aspect of the thigh providing sensory function to the fascia and skin of the medial aspect of the leg to the level immediately distal to the tarsus.

The obturator nerve forms from the continuation of the ventral branch of the fifth lumbar nerve, a small branch of the ventral branch of the sixth lumbar nerve and usually from one or two slender branches of the fourth lumbar nerve. It courses caudo-ventrally along the ilium to the cranial end of the obturator foramen. It splits into several branches to innervate the adductor, pectineus, gracilis, quadratus femoris, obturatorius externus and internus muscles. The obturator nerve provides the main adductor function to the hind limb.

The cranial gluteal nerve arises primarily from the ventral branches of L6 and the first sacral (S1) nerve. It innervates the: tensor fascia lata, which flexes the hip joint and extends the stifle; gluteus medius muscle, which extends the hip, abducts the limb and rotates the femur; and the gluteus profundus muscle, which abducts the thigh and rotates it medially.

The caudal gluteal nerve arises from ventral branches of the first (S1) and second (S2) sacral nerves. It innervates the: gluteobiceps muscle, which extends the hip, stifle and hock, and also flexes the stifle and abducts the limb; gluteus medius muscle, which extends the hip, abducts the limb and rotates the femur.

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The sciatic nerve is derived mainly from the last lumbar (L6) and first two sacral (S1 and S2) components of the lumbosacral trunk. The sciatic nerve innervates the muscles of the pelvis and upper thigh, which serve as extensors of the hip and hock and flexors of the stifle and have a role in both abducting and adducting the limb and also extending the stifle. The sciatic nerve divides into the peroneal (fibular) and tibial nerves at the mid-thigh level.

The peroneal nerve, a branch of the sciatic nerve, is derived more or less equally from L6 and S1. It courses anteriorly and laterally over the stifle, passing behind the residual head of the fibula under the lateral condyle of the tibia. It innervates the muscles of the anterior aspect of the lower limb below the stifle. These muscles flex the hock and extend the digits. The peroneal nerve branches into the superficial and deep peroneal nerves. The superficial peroneal nerve divides at the middle of the metatarsus into the dorsal common digital nerves III and IV. The dorsal common digital nerve IV innervates the lateral aspect of the metatarsus and becomes the dorsal abaxial digital IV nerve, which innervates the dorso- lateral aspect of the IV digit. The dorsal common digital III nerve branches into the dorsal common digital II nerve, which becomes the abaxial digital III nerve and innervates the dorso-medial aspect of digit III; and the dorsal common digital III nerve, which joins with the deep peroneal nerve to form a communicating branch before dividing into the dorsal axial digital III and digital IV nerves. These two nerves innervate the dorsal axial region of digits III and IV, respectively. The communicating branch also joins with the axial plantar digital nerves, branches of the tibial nerve in supplying the axial region of the digits III and IV. The various branches of the peroneal nerve provide sensory supply to the dorsal, dorso-medial and dorso-lateral aspects of the pastern.

The tibial nerve, a branch of the sciatic nerve, is primarily derived from L6 and S1 with a small contribution from S2. Following its separation from the peroneal nerve, it passes between the two heads of the gastrocnemius muscle and innervates the muscles that flex the stifle, extend the hock and flex the digits. The tibial nerve courses down the plantar aspect of the lower limb, dividing into the medial and lateral plantar nerves at the level of the hock continuing down the respective sides of the flexor tendons. The lateral nerve courses into the digit as the abaxial plantar nerve of the IV digit and innervates the planto- lateral aspect of the IV digit. The medial plantar nerve divides into the plantar common digital II and III nerves. The plantar common digital II becomes the abaxial plantar digital

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nerve III digit and innerves the planto-medial aspect of digit III. The plantar common axial digital nerve III divides into the plantar axial digital nerves III and IV, which innervate the planto-axial regions of digits III and IV. The various branches of the tibial nerve provide sensory supply to the plantar, planto-medial and planto-lateral aspects of the pastern.

2.5.2 Nerves of the forelimb of cattle The brachial plexus is formed by the anastomosis of the roots of the ventral branches of the last three cervical (C6 – 8) and first two thoracic nerves (T1 – 2). The brachial plexus gives rise to the suprascapular, subscapular, pectoral, musculocutaneous, axillary, radial, ulnar and median nerves.

The suprascapular nerve supplies the supraspinatus muscle, which is a powerful extensor of the shoulder; and the infraspinatus muscle, which serves as a lateral collateral ligament of the shoulder, and may also assist with extension and flexion of the shoulder, and abducts the forelimb.

The subscapular nerve supplies the subscapular muscle, which has the function of adduction of the forelimb and flexion of the shoulder.

The pectoral nerve supplies the pectoral muscles, which retracts the limb.

The musculocutaneous nerve supplies the coracobrachialis muscle, which adducts the forelimb and flexes the shoulder; and the biceps brachii muscle, which extends the shoulder and flexes the elbow.

The axillary nerve innervates the teres major, teres minor, deltoideus and part of the subscapular muscles, which act as flexors of the shoulder and can both adduct and abduct the limb.

The radial nerve courses ventrally and caudally and transverses the musculo-spiral groove of the humerus. It innervates the triceps muscle, which extends the elbow and the extensor muscles of the carpus and digital joints. The radial nerve exchanges fibres with the musculocutaneous nerve to provide sensory function to the dorsal aspect of the third digit and the axial aspect of the fourth digit.

The median and the ulnar nerves innervate the true flexor muscles of the carpus and the superficial and deep digital flexor muscles. Sensory function to the plantar, planto-medial

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and planto-lateral aspects of the pastern is supplied by the median and ulnar nerves. The dorsal branch of the ulnar nerve provides sensory function to the dorso-lateral aspect of the pastern.

2.6 Musculo-Skeletal Causes of Recumbency in Cattle This section covers the musculo-skeletal conditions that can cause primary recumbency in cattle or are a complication of recumbency.

2.6.1 Neuropathies

2.6.1.1 Neuropathies of the hindlimb The femoral nerve was considered to be not particularly vulnerable to damage as it is well protected along its course (Divers, 2004, Parkinson et al., 2010, Vaughan, 1964). The most likely cause of femoral nerve damage is from a stretch-injury to a calf stuck in hip-lock during a difficult birth (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Paulsen et al., 1981). It could occur from over-stretching when recumbent cattle attempted to rise with their hind limbs retracted caudally (Divers, 2004, Parkinson et al., 2010) or from pressure from an abscess, haematoma or tumour (Paulsen et al., 1981).

Experimental sectioning of the femoral nerve unilaterally in two calves at the medial aspect of the upper thigh immediately proximal to the saphenous branch caused the leg to be constantly semi-flexed and unable to bear weight (Vaughan, 1964). The claw only lightly touched the ground and the stifle buckled when trying to walk. The patellar reflex was absent. After 10 days atrophy of the quadriceps muscle was apparent and was marked after 30 days. There was a loss of skin sensation on the medial aspect of the thigh to the tarsus.

The patellar reflex must be absent or depressed for femoral nerve damage to be diagnosed (Constable, 2004) although it is more likely to be caused by a lesion of the fourth and fifth lumbar cord segments (Smith-Maxie, 1997).

Obturator nerve paralysis commonly occurs with dystocia when an oversized calf compresses the nerve roots of L5 and L6 or the nerve where it courses down the medial shaft of the ilium. Cows with a unilateral paralysis had a tendency to slip and fall with abduction of the limb whereas cows with bilateral paralysis were unable to stand (Parkinson et al., 2010). Obturator nerve damage can also occur if cattle slip and fall with their legs in severe abduction (Divers, 2004).

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Experimental bilateral sectioning of the obturator nerves in two calves and two cows produced different results: the hindlimbs of the calves were abducted when they were forced to run but they were able to stand normally, whereas the cows collapsed into total abduction and were unable to rise. Differences in their weight and agility may explain the variations in presentation (Vaughan, 1964). However, similar experimental sectioning of the obturator nerve produced different results, as only one of 11 adult cattle was unable to rise without assistance immediately after bilateral sectioning and this cow was subsequently found to have ruptured stifle ligaments. Eight of the ten cattle had ataxia on a slippery surface and their legs spread laterally but their gait was normal at the walk (Cox et al., 1975).

No references could be found in the literature to damage to the cranial gluteal and caudal gluteal nerves.

The sciatic nerve can be damaged from a difficult calving when the “sixth lumbar nerve root is compressed against the prominent ridge on the sacrum before it joins the first two sacral roots to form the sciatic nerve” or following intra-muscular injections into the pelvic muscles, particularly in small or thinly muscled animals. Cows with sciatic nerve damage may present with a dropped hock and knuckled fetlock when standing or they may be recumbent (Parkinson et al., 2010). Constable (2004) described sciatic nerve injury as “rear limb weakness and knuckling of the fetlock”. Vaughan (1964) stated that the sciatic nerve is rarely injured because it is well protected by the surrounding muscles. It could occur in association with a femur fracture or severe trauma to the hip. Experimental sectioning of the sciatic nerve in one leg of two calves at the level of the hip joint resulted in an “almost total paralysis” of the hind limb. The stifle and hock joints were extended and the fetlock flexed, which left the dorsal pastern in contact with the ground. The only skin sensation present on the hind limb was at the medial thigh, which is innervated by the saphenous nerve (Vaughan, 1964). Divers (2004) disagreed with Vaughan’s statement that sciatic nerve injuries are rare by stating “sciatic nerve injury is common in cattle”, citing various causes including trauma at calving or from intra-muscular injections, ischaemic myopathy or pressure from neoplasia, abscess or pelvic fracture (Divers, 2004).

When the peroneal nerve is damaged the animal stands on the dorsal aspect of the claw and the hock is over- extended. Sensation is reduced or lost to the dorsal aspect of the

Chapter 2: Literature Review pastern (Keown, 1956, Parkinson et al., 2010). Full weight could be taken by the limb when the hoof was manually placed in the normal position but it immediately reverted to the abnormal position as soon as the first stride was taken (Vaughan, 1964). The peroneal nerve is susceptible to damage where it crosses the head of the fibula on the anterior lateral stifle as it lies superficially in this position (Divers, 2004, Keown, 1956, Parkinson et al., 2010, Vaughan, 1964). Histological sections of a heifer with clinical signs of peroneal damage taken 8 cm distal to the stifle showed total disruption of the axons, characterised by lack of myelin sheaths at low power and no intact myelin sheaths at high power (Cox et al., 1975). Peroneal nerve damage can be associated with dystocia (Constable, 2004) when the trauma is only to the part of the sciatic nerve from which arises the peroneal nerve (Vaughan, 1964).

The tibial nerve is less likely to be damaged as it is well protected by surrounding muscles (Divers, 2004, Parkinson et al., 2010, Vaughan, 1964), and severe trauma to the gastrocneumius muscle must have occurred for it to be injured discretely (Smith-Maxie, 1997). Tibial nerve damage will present with paralysis of the extensors of the hock and flexors of the digits causing the stifle to be dropped, the hock to be hyper-flexed and a mild over-flexion of the fetlock, causing it to be knuckled forward. The claw remains in contact with the ground normally and sensation may be lost to the plantar aspect of the limb below the hock in severe cases (Parkinson et al., 2010). Tibial nerve damage must be differentiated from gastrocnemius muscle rupture (Divers, 2004).

2.6.1.1.1 Calving Paralysis The passage of an over-sized calf through the pelvic canal can cause damage to the pelvic nerves and result in paralysis of the dam. This is referred to as calving paralysis, maternal obstetrical paralysis and obturator paralysis. It most commonly affects first-calving heifers but can also occur in multiparous cows. It ranges in severity from a mild paresis, a weakness and knuckling of one or both hind limbs; to a complete inability to rise (Blood et al., 1979).

The term “obturator paralysis” has been used synonymously with calving paralysis following experimental bilateral sectioning of the obturator nerves which resulted in “a collapse of the hind legs into total abduction”(Vaughan, 1964).

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However, as damage to the obturator nerve cannot account for the fetlock flexion that is often associated with calving paralysis, the syndrome was investigated in more detail (Cox and Martin, 1975). After sectioning the obturator nerve bilaterally, they found that whilst abduction of the limbs occurred on slippery concrete and caused them to fall, cattle were usually able to stand without assistance when the surface provided good traction. They subsequently sectioned the L6/sciatic nerve root and ataxia and recumbency with flexion of the fetlock occurred. The flexion of the fetlock that is commonly associated with calving paralysis could only be explained by damage to the peroneal/sciatic nerve (Cox and Martin, 1975, Cox et al., 1982). The L6 nerve root passes under the acute ventral ridge of the ventral sacrum and they proposed that this would be the likely point of trauma during a dystocia. As the L6 nerve root is usually larger than the obturator nerve they stated that “more muscle denervation should result from L6 damage than from obturator nerve damage” (Cox et al., 1982). The presentation of the clinical signs of calving paralysis will depend upon the extent of the nerve damage to the nerves within the pelvic canal, so considerable variation is possible (Cox, 1988).

Galabinov (1966) conducted a detailed investigation of calving paralysis in 103 cows. He described the variations in clinical presentations and the histological findings from 15 of the cows. He subsequently published a second article involving 155 cows (Galabinov, 1972). Both articles were written in German and I only had a basic translation of them available. He concluded: Both the sciatic and obturator nerves can be damaged during parturition; The obturator nerve is less important as it supplies less significant muscles of the hind limb and is of a smaller size; The nerve damage is usually only to one side as the calf passes sideways through the pelvic canal; The clinical syndrome will vary depending on the severity and site of the trauma to the nerves, as will the extent and position of deficiencies of sensation of the hind limb. He found grossly, that there were deep and superficial haemorrhages to the sciatic and obturator nerves, and histologically, there was haemorrhagic infiltration, oedema, hyalinisation, thrombosis of the vessels and degeneration of nerve fibres (Galabinov, 1966, Galabinov, 1972).

Calving paralysis was described as a paralysis of the hind limbs of cows due to damage at the time of calving to the intra-pelvic portions of the sciatic and obturator nerves. “It is manifest as obturator, peroneal or tibial nerve paralysis in any combination or degree” (Fenwick,

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1972). Whilst the obturator nerve was commonly damaged in first-calving heifers following a difficult parturition, the sciatic was more commonly affected (Divers, 2004).

Yet, despite this, the obturator nerve is still commonly thought of as the main cause of calving paralysis. A recent textbook (Parkinson et al., 2010) states “obturator paralysis is the most common of the paralyses associated with calving” and shows a picture entitled “calving (obturator) paralysis”. In regard to the sciatic nerve they state that “damage to the sciatic nerve may occur associated with intra-pelvic pressure damage during calving” (Parkinson et al., 2010). Further work in this field was encouraged by Cox et al (1975) by expressing their hope that their “present study will stimulate examination of the L6/sciatic nerve during necropsy of cattle having calving paralysis”.

2.6.1.2 Neuropathies of the forelimb One each of the suprascapular, radial, median and ulnar nerves on one leg of two calves were experimentally sectioned to investigate the dysfunction (Vaughan, 1964). Loss of the function of the suprascapular nerve resulted in atrophy of the supra- and infraspinatus muscles over two to four weeks but very little dysfunction when standing or moving. Sectioning of the radial nerve produced a “complete extensor paralysis as a result of which the elbow, carpal and phalangeal joints were flexed and the front of the claws rested on the ground”. The leg was unable to bear any weight and the claws were dragged whilst walking. Skin sensation was reduced on parts of the anterior aspect of the lower leg below the knee. The median and ulnar nerves were sectioned simultaneously and this produced a stiff “goose-step-like” walk. The standing position was not affected initially but after two weeks there was noticeable hyper-extension of the carpus. Skin sensation was lost along the posterior aspect of the lower limb from the elbow down (Vaughan, 1964).

Forelimb neuropathies may involve the entire brachial plexus or be confined to just the radial nerve. Damage to the brachial plexus can occur from prolonged compression between the scapula and ribs associated with lateral recumbency (Parkinson et al., 2010). This involves damage to all of the nerves of the plexus, leading to total paralysis of the forelimb. Radial nerve paralysis is usually a complication of recumbency with pressure causing trauma to the radial nerve as it passes over the humerus (Parkinson et al., 2010). Cattle with brachial plexus paralysis are unable to bear weight on the affected limb and the fore limb appears to “hang from the thoracic girdle” (Parkinson et al., 2010). There is a complete

Chapter 2: Literature Review paralysis of the fore limb. This can be differentiated from radial nerve paralysis where weight can be born if the leg is manually placed directly under the cow. (Parkinson et al., 2010). This is because the muscles of the shoulder are still functioning in a radial nerve case.

Loss of sensation to the anterior aspect of the digit may be noticed in severe cases of radial nerve paralysis (Divers, 2004). It can be damaged from injury to the fore limb or from pressure from compartmental syndrome during prolonged lateral recumbency. Adult cattle with unilateral radial nerve paralysis often present as downers, especially if they are on surfaces with poor traction, whereas lighter, younger animals are often able to walk on three legs. Brachial plexus damage will present with the animals unable to bear weight on the limb. It could present bilaterally following a fall with abduction of both limbs. Excessive traction to the forelimbs during parturition could damage the plexus in a new-born calf. Infection, wounds or lacerations to the axillary region may also cause radial nerve paralysis (Divers, 2004).

2.6.2 Skeletal injuries Hip dislocation usually arises from trauma from mounting activity, falls or from struggling to rise when down from other causes, such as milk fever. Cases can be either ambulatory or non-ambulatory. The direction of the luxated hip can vary from cranio-dorsal, caudo-dorsal, caudo-ventral or cranio-ventral (Parkinson et al., 2010).

Fractures of the pelvis may result from injuries received when a cow falls or is knocked over by another animal, especially a heavy bull (Parkinson et al., 2010).

Fractured limbs occur in cattle usually involving the metatarsal and metacarpal bones. These can be treated successfully in younger animals with splints but are more difficult in adult or heavier cattle. The scapula, humerus, radius, femur and tibia may occasionally be affected. Treatment of these is usually unsuccessful, except in calves where internal fixation techniques can be used. Some will heal given time and confinement but animal welfare considerations must be carefully considered (Parkinson et al., 2010).

The lumbo-sacral and sacro-iliac ligaments can be strained during a dystocia or over- exertion from trying to rise when recumbent for other reasons (Parkinson et al., 2010).

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2.6.3 Soft tissue/muscle injuries The gastrocnemius originates from the distal femur and inserts onto the calcaneal tuber of the hock. Its action is to flex the stifle and extend the hock (Getty, 1975). It can be damaged from falling or struggling to rise (Parkinson et al., 2010).

Damage to the collateral or cruciate ligaments can present as lameness (Parkinson et al., 2010). Occasionally, complete rupture of all of the ligaments of the femoro-tibial joint may occur and result in an inability to rise.

2.6.4 Compartment Syndrome The hamstring group of muscles (biceps femoris, semitendinosus and semimembranosus) are particularly prone to damage in a recumbent cow. This damage can occur within as little as three to six hours of lying in sternal recumbency, especially if the surface is hard and/or the animal is heavy (Cox, 1982). The compressed muscles swell as lymphatic fluid and venous blood become trapped within the fascial compartments of the muscle. These hydrostatic forces progressively reduce the arterial blood supply causing an ischaemic myonecrosis. This in turn leads to further swelling, which causes more ischaemic myonecrosis and a destructive cycle ensues (Van Metre, 2001). The semitendinosus has the thickest fascial boundaries and is most at risk of this damage (Cox et al., 1982). Conditions associated with hypotension, such as post-parturient hypocalcaemia (milk fever), potentiate the risk of this syndrome because the reduced blood pressure is less able to perfuse the swollen muscle areas (Van Metre, 2001). The weight of the animal, the surface they are resting on and whether they are rolled manually are other important factors (Van Metre, 2001). Trauma from the animal trying to rise can also cause haemorrhage within the muscle bellies further contributing to the increased pressure (Cox, 1981).

Biochemical and haematological levels were used as predictors of likely recovery of downer cows (Clark et al., 1987). A range of blood tests were performed from 433 peri-parturient recumbent cows submitted over two years by veterinary practitioners in New Zealand. Their preferred model used serum urea, aspartate amino transferase (AST) and days sampled, from days zero to seven. They fitted probability of recovery contours using the log of these two enzymes with the curves representing 5, 10, 30, 50 and 70% recovery. The probability contours were adjusted according to the number of days sampled. Creatinine phosphokinase (CK) was not included, as it did not significantly improve the model.

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However, if there was evidence of liver damage (elevation of glutamate dehydrogenase GDH) a CK – urea model was used. I consider that this model for prediction of recovery has merit but is of limited use if the veterinarian has failed to thoroughly examine the recumbent cow and has missed diagnosing any primary or secondary damage that would prevent the cow from recovering irrespective of the level of muscle damage.

Predictions of non-recovery were also investigated using a ‘critical’ level representing a less than 5% probability of recovery (Clark et al., 1987). For CK this threshold varied each day, as shown in Table 2.1

Critical levels are highest initially (50 times upper limit of normal reference range) and reduce to 10 times normal levels at seven days recumbent. This is due to the short half-life of CK, which has been calculated to be two to four hours in cattle (Anderson et al., 1976). Cows with initial severe muscle damage can be close to normal range after seven days (Clark, 1984). For AST, the critical level was 890U/l, representing 7.4 times the upper limit of normal reference range (25 – 120 U/l at 30 degrees C). This was constant over the first seven days of recumbency (Clark et al., 1987).

This model for prediction of non-recovery has merit in situations where a thorough clinical examination of the recumbent cow has failed to establish a cause, or where the examination has revealed damage of only a minor level from which the cow would reasonably be expected to recover. Knowledge of the level of muscle damage could change the prognosis in such a case.

Table 2.1. Critical CK levels relative to days down when sampled (Clark et al., 1987) Days recumbent Critical CK level Times normal range1 0.5 12,200 33 1 18,600 50 2 16,300 44 3 14,000 38 4 10,900 29 5 8,500 23 6 6,200 17 7 3,900 10 10-327 U/l

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Another study took daily blood samples from 262 recumbent cows over the period of their recumbency (Shpigel et al., 2003). They looked at the predictive values of CK, AST and lactate dehydrogenase (LDH). They assessed the value of these enzymes for predicting whether the recumbent cows would recover. The tests were analysed using receiver operating characteristic (ROC) curves and Bayesian statistics. By considering the area under the curves (AUC), they found the ability of the three enzymes to predict failure to recover was significant. AST’s ability to do so was significantly better than the other two, with measurements made on day two and three giving the best results. The superiority of AST could be due to the slower release of AST from intracellular organelles and its longer half- life in serum, which results in a slower increase in its activity after muscle damage and more persistently high levels (Valberg et al., 1996). By the fourth day of recumbency, all of the enzymes were useless for the prediction of non-recovery. However, AST and LDH were still useful for the prediction of recovery (Shpigel et al., 2003). When they applied the statistical analysis used by Clark et al (1987) to their data they found remarkably similar critical levels for a 5% probability of recovery.

2.6.5 Secondary neuropathies An experiment was performed where 16 cows were anaesthetised for a period of six, nine or 12 hours in right sternal recumbency on a rubber mat (Cox et al., 1982). The position was to mimic the typical milk fever position. Eight of the cows were able to stand within three hours of completion of anaesthesia but the other eight remained recumbent and became downer cows. The right pelvic limb of the downer cows was rigid and obviously swollen but this was apparent in some of the ambulatory cows as well. Creatinine Kinase (CK) concentrations were markedly elevated at 12 and 24 hours for all cows and there was no significant difference between the recumbent and the ambulatory groups. By day two and four, the enzyme concentration levels had decreased markedly in the ambulatory group and remained significantly higher in the downer group. However, muscle damage did not explain while some animals could stand at the end of the anaesthesia and others could not. The most marked and consistent gross change at necropsy of the downer cows was extensive signs of damage to the right sciatic nerve in the region caudal to the proximal end of the femur. Peroneal damage was also found in some cows at the level of the lateral proximal tibia. In contrast, normal clinical function of the right limb in the ambulatory cows indicated

Chapter 2: Literature Review

minimal sciatic nerve damage. The damage to the sciatic nerve could have been due to direct pressure on the nerve from the surface they were lying on but it could also be due to pressure to the nerves from the swollen muscle bellies (Cox et al., 1982).

This experiment showed the importance of secondary nerve damage in determining the outcome of a downer cow. The cause of the primary recumbency, the anaesthetic, was completely resolved but within three hours of its completion some cows were unable to rise due to secondary neuropathy.

2.7 Management of Recumbent Cattle No evidence-based research could be found on the quantitative effects of nursing quality on recovery. The information contained in the references, cited, below, was valuable as a guide to the principles of nursing care but the lack of scrutiny of it must be taken into account. The article by Huxley et al (2010) was a summary of a forum of experienced cattle veterinarians where they discussed different aspects of management of recumbent cattle. It was the most comprehensive that could be found in the literature covering these aspects.

There is a need for robust research to be undertaken in this area of management.

2.7.1 Management Plan Very little peer-review information was found in the literature (Huxley et al., 2010) in regard to the most effective treatment and management of downers, making it an area that draws heavily on the veterinarian’s experience when making decisions.

The overall on-farm nursing and management of downer cows was considered more important than the veterinary treatment in regards to the likely outcome (Huxley et al., 2010). Part of the veterinarian’s role is to ensure the stock carers’ are educated in the various aspects of the animals’ management and that it is effectively implemented (Huxley, 2006).

Developing a therapeutic nursing plan was considered “indispensable” to prevent secondary damage following recumbency (Belloli et al., 1996).

2.7.2 Treatment Treatment includes the use of various therapeutic agents, such as calcium salts, non- steroidal anti-inflammatory drugs and physical agents, such a physiotherapy and hobbles.

Chapter 2: Literature Review

2.7.2.1 Minerals Minerals, such as calcium, magnesium and phosphorous are used to treat cows recumbent with metabolic conditions, such as milk fever and grass tetany (Parkinson et al., 2010, Radostits et al., 2010).

2.7.2.2 Non- steroidal anti-inflammatory drugs Non-steroidal anti-inflammatory drugs (NSAID) are advocated for use in the treatment of recumbent cows (Huxley et al., 2010) and are indicated for many primary conditions, especially if involving nerve (Smith-Maxie, 1997) or muscle damage. They are also indicated for the secondary neuropathies and myopathies that may occur once the cow becomes recumbent. There are several different drugs registered for use in cattle in Australia: meloxicam, tolfenamic acid, ketoprofen and flunixin.

2.7.2.3 Physiotherapy Physiotherapy can help recovery from nerve injuries (Smith-Maxie, 1997). Physiotherapy can limit ischaemic myonecrosis by stimulating venous return and muscle perfusion (Huxley, 2006). It can be applied in various forms, ranging from massage and manually flexing and extending the limbs to stimulating the cow to encourage her to move. This can be done by yelling, kneeing the cows in the ribs, the judicious use of a cattle prodder or lifting the cow. The cattle prodder can also be used to make the cow kick her hind limbs vigourously when lying in a lateral position. Lifting can be as simple as helping support the tail when she tries to stand or can lifting with a mechanical device, such as a hip clamp (Parkinson et al., 2010).

2.7.2.4 Hobbles Hobbles are a treatment aid for cows with a displaced leg stance, such as cows with obturator paresis/paralysis (Huxley, 2006). Hobbles are applied above the hock or fetlock to prevent excessive abduction of the hindlimbs (Parkinson et al., 2010).

2.7.2.5 Splints Splints, casts or bandages can help recovery for some neuropathies, such as sciatic and peroneal where there is knuckling of the fetlock (Parkinson et al., 2010, Smith-Maxie, 1997).

2.7.3 Welfare The prognosis is the most important decision the veterinarian needs to make when attending downer cows (Andrews, 1992). An important part of the welfare of the recumbent

Chapter 2: Literature Review cow is the stock person’s ability and attitude so this must be factored in when assessing the animal’s prognosis (Harwood, 2003). When assessing the prognosis for a downer cow, a variety of factors need to be considered, including the history, clinical symptoms, diagnosis, ability to treat the condition successfully, and the stock person’s ability to nurse the patient. Those judged to have a poor or hopeless prognosis should be euthanased immediately. Those that are nursed should be revisited within four days to re-assess their condition and decide if treatment should continue (Huxley, 2006). The median number of days to pass before downers should be culled, as recommended by a group of experienced cattle veterinarians, was five with a range of three to seven (Huxley et al., 2010), although this would vary depending on the level of nursing care. Statistics showed that about half of the downer cows rose within four to seven days (Andrews, 1992) so the prognosis for cows down for more than ten days is poor. Some cows may recover after extended periods of nursing.

2.7.3.1 Pain aspects Pain scores for downer cows in a variety of situations as determined by a group of experienced cattle veterinarians varied considerably with conflicting opinions as to whether the compression of the dependant leg made it “numb” or painful (Huxley et al., 2010).

Floatation tanks were considered the least painful method of lifting downer cows, followed by inflatable bags, nets and two slings with Bagshaw hip hoists considered to be the most painful, with a pain score of 7 out of 10 (Huxley et al., 2010).

2.7.4 Euthanasia Euthanasia is one component of the management of recumbent cattle and is discussed by various authors (Andrews, 1992, Harwood, 2003, Huxley, 2006, Huxley et al., 2010, Parkinson et al., 2010). Factors considered by these authors to prompt euthanasia include: animals suffering from conditions with poor or hopeless prognosis; animals showing signs of pain not responding to appropriate treatment, such as non-steroidal anti-inflammatory drugs; depressed cows that do not respond to appropriate treatment within the expected time period; cows in persistent lateral recumbency despite measures to help them remain in the sternal position; stock carers who are unable to provide appropriate nursing conditions

Chapter 2: Literature Review or devote adequate amounts of time for the animal’s care; and animals that have ‘lost the will to live’.

2.7.5 Nursing The three most important aspects of nursing were considered to be the provision of accessible feed and water, regular turning and lifting, and deep, soft bedding with good footing (Huxley et al., 2010).

Belloli et al (1996) listed their most important factors to be confining the cow in a single box on comfortable bedding, changing her position frequently and lifting every two to four hours.

A nursing plan for recumbent cattle involves the following factors:

2.7.5.1 Bedding As recumbent cattle are particularly susceptible to secondary myopathies and neuropathies it is important that they are quickly removed from a hard surface and suitable bedding is provided. Irreversible secondary damage to the peripheral sciatic nerve was shown to occur within as short a period of time as 6 hours when anaesthetised cows were place in sternal recumbency on rubber matting (Cox et al., 1982).

The animal should be provided with a clean, dry, warm and comfortable surface, which provides good footing for purchase when trying to stand (Huxley, 2006). The lying surface should also be soft (Parkinson et al., 2010). Deep straw bedding of sufficient thickness to prevent the cow working through it when they tried to move is suitable (Huxley, 2006).

Cox and Marion (1992) concluded that a bedding of sand can be a suitable surface as it provides good footing, manure is easily removed from it and urine drains through it. A cow was nursed in excess of 80 days on a bedding of sand without complications, such as decubital ulcers and urine scalding arising. However, this article was based on the nursing of only one cow. They noted that straw and wood shavings mix with the urine and faeces and become soaked by them, so are a less suitable bedding. Huxley (2006) recommended that a bedding of sand should be at least 20 cm thick.

Chapter 2: Literature Review

2.7.5.2 Rolling Frequent rolling and/or lifting was considered the second most important aspect of nursing downers behind the provision of adequate feed and water (Huxley et al., 2010). If the cows are unable to roll themselves from side to side they must be manually rolled. This should be done as often as every three hours (Huxley, 2006).

2.7.5.3 Lifting Regular lifting was considered a very important nursing factor (Huxley et al., 2010). Views varied as to the usefulness of lifting cows (Andrews, 1992) as whilst they can be of benefit in the diagnosis and treatment of downers they can also cause damage if used incorrectly. Huxley (2006) discussed the various options for lifting cows, such as manually lifting by the tail, using nets, slings, cradles and harnesses, inflatable bags and floatation tanks. All of these methods have their own advantages and disadvantages so it is important that veterinarians instruct the stock carers’ on their proper use to ensure due consideration is given to the animals’ welfare. If the animals respond favourably to lifting, they can be lifted four or more times per day, if practical; but, if they simply hang in the device, they should be lowered after only a few minutes (Huxley, 2006).

Floatation tanks are used for nursing recumbent cows as the buoyancy provided by the water helps many cows to be able to stand in the tank. Their response when first immersed can help in assessing the downer cow as their chance of recovery is poor if they are unable to stand in the water. Cattle that stood apparently normally on all limbs during the first flotation treatment were nearly three times more likely to survive than those that had an asymmetric stance or were unable to stand (Burton A.J., 2009). Cows are left in the heated water for up to eight to ten hours per day and may need several days of floatation before recovering. Nine out of 15 downers diagnosed with muscle damage recovered after being treated in a floatation tank (Chesterton, 2011), a significant outcome.

2.7.5.4 Shelter Recumbent cattle need to be protected from adverse weather effects. The provision of shelter was ranked sixth out of eight when considering management/nursing factors that impact on the recovery of downers (Huxley et al., 2010).

Chapter 2: Literature Review

2.7.5.5 Feed and Water Adequate feed with sufficient energy and fibre is important, along with ample water. The feed and water must be within easy reach of the downer cow and away from other cattle (Andrews, 1992). The provision of adequate feed and water was considered to be the most important nursing factor and it can be used as a guide to indicate the overall level of nursing care being provided to the cow (Huxley et al., 2010).

2.7.5.6 Milking Cows recumbent for more than 12 hours should be milked twice daily to reduce the risk of mastitis and for comfort (Huxley, 2006).

2.7.5.7 Tender love and care “Tender love and care” are an essential part of the nursing of downer cows and can make the difference between recovery and euthanasia (Huxley, 2006). Whilst it is difficult to define and will vary in different situations, it can be thought of as all of the various components of the management plan that makes the cow comfortable.

Chapter 3: General Materials and Methods

Chapter 3. General Materials and Methods

3.1 Data Collection I work as a veterinarian at the Tarwin Veterinary Group (TVG), a mixed animal practice in South Gippsland, Victoria, Australia. The clinic has a strong component of commercial dairy farms with an average herd size of approximately 260 cows, ranging from 80 – 1100 cows. The area has a temperate climate with an annual average rainfall of 900 mm with the majority falling in the winter/spring period. The production system is a winter rainfall, dry land system. It is typically pasture based with most producers feeding a processed supplement or mixed feed (1.2 – 1.5 T/cow/year) and conserved silage and pasture hay. Limited amounts of crops are grown, such as turnips, rape and maize. Irrigation is unusual. Average stocking rate is 2.4 cows/Ha with average production per cow being 440 kg Milk Solids and production per hectare of 790 kg Milk Solids. Three quarters of the farms have a split calving pattern with the majority of the cows calving over a three month period in the winter/spring period and a shorter autumn calving group. The remaining herds are strictly seasonal calving during the winter/spring.

I conducted my field studies of recumbent cows in my local area during two three-month periods in the winter months, from 1st June to 30 September of 2011 and 2012.

3.2 Study design The study was “observational” in design rather than “experimental”, as it involved observing the way farmers managed their recumbent cows under normal farm conditions. To conduct a randomised controlled trial (RCT) would have required all of the cows to be nursed under standardized conditions and then varying specific factors in a randomized manner. This could only be achieved properly by having a centralised nursing centre, which was impossible from both cost and logistical perspectives. Being an observational study, I was only able to observe the effect of the management provided to the cows by the famers (exposure on the study subjects), without being able to assign specific types of management to the cows. The methodological problems that observational studies are vulnerable to are: bias; confounding; and chance. My results could be accused of being biased, due to the subjective nature of some measures, in particular the nursing scores. In an attempt to prove that high quality nursing improved the chance of a successful outcome, I could have tended

Chapter 3: General Materials and Methods

to allocate nursing scores on the basis of outcome. I was aware of this possible flaw in my study design, so I was as objective as possible, allocating the nursing score on the basis of the defined criteria, without consideration of the outcome. There was a large variation in the type and severity of the primary cause of the recumbency, which made it difficult to judge if there were other factors confounding the association between nursing care and outcome. This problem was inherent in the study design. This variation in the type and variation of the primary damage would have also made it impossible to conduct an experimental study, as the starting point of each cow was not the same. Statistical associations were based on case/control studies using p values of less than 0.05 and 95% confidence intervals, as described in Section 3.9, in an attempt to truly judge the association between exposure and outcome.

3.3 Ethics The Faculty of Veterinary Science Animal Ethics Committee deemed that ethics approval was not required for this research, as the study involved observation of the way farmers managed their recumbent cows under normal field conditions. The clinical examinations performed on the cows, including the single blood sample that was taken from many of the animals, were considered to be normal veterinary procedures, rather than experimental in nature.

3.4 Selection of Cases Cows were included in the study if they:

• Were recumbent for more than one day from any cause providing they were bright, alert and responsive (downer cow)

• Were initially depressed from metabolic or per-acute sickness but had recovered from the depressed state

• Were adult, as calves and yearlings were not included

• Had adequate history and follow-up information available to allow full assessment

• Did not have a recorded episode of recumbency in the previous thirty days

Cows recumbent from calving paralysis or back injury that had recovered within less than 24 hours were included for the chapters on calving paralysis, sciatic and femoral nerve injuries.

Chapter 3: General Materials and Methods

Dairy clients in the local area had been informed of the intended field research by a variety of methods prior to each period of study. The object was to attend as many downer cows as possible during the time period and closely follow their progress. It was important to be able to accurately determine the primary cause of the recumbency and record the conditions under which the cows were nursed. They were revisited, as appropriate, to ascertain their progress in recovering from the primary condition and to look for the development of secondary complications. The farmers were not charged for any of my visits.

Any potential conflict of interest between TVG and my research was prevented by the following protocols: I could attend cows known to be recumbent from calving paralysis as a primary case because the majority of farmers would normally only seek anti-inflammatory drugs by prescription from TVG and not require veterinary attendance. All other types of downers were attended by TVG veterinarians prior to my first visit. TVG veterinarians referred appropriate cows to me, which avoided research time being spent on cows recumbent from a variety of medical and metabolic conditions, such as peri-parturient hypocalcaemia (milk fever), acute Salmonellosis, or primary hip dislocation, which were not part of the study. The focus of the research was on downer cows, as defined previously.

Where ever possible, the cattle were attended on the first day of their recumbency, either by a TVG veterinarian or myself. A full clinical examination was performed to determine the initial cause of the recumbency, whether medical or musculo-skeletal and to determine if any secondary damage had already occurred, particularly to the musculo-skeletal system. Blood was taken between the second and seventh day of recumbency (day 1 – 6) for later analysis by Veterinary Clinical Pathology, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne. Analysis for Creatinine Phosphokinase (CK), Aspartate Amino Transferase (AST) and Urea concentrations were undertaken on the serum. Results were not known at the time of supervising the cows to avoid potentially biasing outcome observations. Results were later compared to the model of non-recovery proposed by Clark et al (1987). If the cow was initially visited on the first day of recumbency (day zero) she would be revisited over the following days, where possible, to collect the blood sample. Cows suspected to be suffering from kidney failure were investigated by determining the specific gravity of the urine and blood analysis for Creatinine and Urea.

Chapter 3: General Materials and Methods

Farmers were not required to nurse the cow for any prescribed period as I was interested in observing the farmers’ normal approaches to nursing management. However, encouragement was given to continue nursing for a week, if still recumbent, unless the cow needed to be euthanased on welfare grounds. Cows were usually revisited a number of times during their recumbency, with the revisits conducted on an ‘at needs’ basis and as time allowed. An effort was made to revisit them close to day 7, as their status at this period of time was determined to be a key outcome. A full clinical examination was performed at each revisit and nursing conditions were recorded.

There were five categories for the causes of the primary recumbency: post-parturient hypocalcaemia (milk fever); protein-energy deficiency; calving paralysis; back injury; and ‘other’. It was considered important to have a cross-section of primary cases and not focus on any one particular group.

3.5 Records An examination sheet was constructed to record all relevant aspects of the history, clinical examination and nursing conditions of the cows, as shown in Appendix 2. Photographs were taken of each cow at each visit as a valuable recording method. Excel spreadsheets were developed to record the details of the cows and to allow analysis of the data.

3.6 Examination Techniques At my first visit the primary cause of the recumbency was determined: if the cow had previously been seen by another veterinarian, this verification relied on a detailed history from the farmer and from the attending veterinarian, in combination with my clinical examination. I either agreed or disagreed with the original primary diagnosis.

A standard veterinary medical examination was performed. Cows had to be bright, alert and responsive to be eligible for the study so any that were depressed were excluded. Any symptoms that developed subsequent to the initial recumbency were noted as they were considered to be secondary complications.

An important part of all visits was a thorough examination of the musculo-skeletal system: With the cow in sternal recumbency the back was carefully examined looking for swellings and painful areas. The vertebral column was examined for misalignments and instability by observing and feeling the dorsal and lateral spinous processes of the lumbar vertebrae. This 32

Chapter 3: General Materials and Methods was re-assessed when the cow was rolled onto her other side. The lumbo-sacral ligament was assessed for damage by testing the amount of movement in the lumbo-sacral joint when rocking the pelvis in a dorso-ventral motion. The pelvic bones were examined to determine if they were fractured. The cow was rolled into lateral recumbency and the hind limb examined for signs of a hip dislocation, leg fracture, ruptured stifle or torn gastrocnemius muscle/Achilles tendon. Limb tone was assessed. Hindlimb flexor-withdrawal reflexes were assessed using an 18G hypodermic needle on the dorsal (peroneal) and plantar (tibial) aspects of the pastern, which was recorded as ‘superficial’ pain and by squeezing the inter-digital area with hoof testers, which was recorded as ‘deep’ pain. The normal response was for the animal to withdraw the limb by flexing the various joints (de Lahunta and Glass, 2009). If no response was observed from the needle an electric cattle prodder was used judiciously as it produced a stronger stimulus. This was important where the leg was cold from lying in wet conditions. The patellar reflex was assessed by striking the patellar ligament with hoof testers (de Lahunta and Glass, 2009). This was recorded to be normal, reduced, absent or increased. The front leg was examined for damage to its bones, joints, ligaments and muscles. Limb tone was assessed in the prone position. Superficial sensation of the skin of the pastern, corresponding to innervation by the radial, ulnar and medial nerves, was assessed by the flexor-withdrawal reflex using an 18G hypodermic needle or electric cattle prodder, as shown in Figure 4.2. ‘Deep’ pain was assessed by squeezing the inter-digital region with hoof testers, as for the hind limbs. Motor function and postural responses were assessed by observing the cow’s response when stimulated to move and when lifted. The direction and amount of strength of each of the four legs was noted, as well as posture and postural responses. If the cow was reluctant to bear weight on her forelimbs when lifted with hip clamps, a chest strap was placed under her sternum for support. If she still lacked forelimb function, forelimb tone was assessed and the flexor- withdrawal response was repeated in the standing position to better assess brachial and radial nerve damage.

Blood for muscle enzyme concentrations was taken if the cow was seen between days one and six of the recumbency. The serum was separated and frozen for later analysis of CK, AST and urea. Blood was not collected from cows that were able to walk after being lifted.

Full details on the examination techniques are discussed in Chapter 4.

Chapter 3: General Materials and Methods

3.7 Diagnosis

3.7.1 Primary cause of recumbency

3.7.1.1 Milk fever Cows allocated into the primary milk fever group had a history of being found recumbent by the farmer in a depressed state with a dry nose and their mentation responded to intravenous or subcutaneous administration of calcium injections. They were usually seen by a TVG veterinarian on either the initial or subsequent day of their recumbency and were usually treated with additional calcium injections. I did not see them until at least the second day of their recumbency and to be included in the study they had to be bright and alert and unresponsive to further calcium injections. Serum calcium levels were not taken but they did not show clinical symptoms of hypocalcaemia at that time.

3.7.1.2 Protein-energy deficiency Cows were allocated into the protein-energy deficiency group by the initial attending TVG veterinarian on the basis of a clinical examination; they were at the late pregnant stage and due to calve in at least the following two to three weeks. They were clinically normal except for symptoms of muscle weakness. Some may have had a positive ketonuria but blood for beta-hydroxbutyrate was not taken. I confirmed the diagnosis based on history and clinical examination when I first attended these cows.

3.7.1.3 Calving paralysis Cows allocated into the calving paralysis group were recumbent with a history of dystocia, swollen vulva and hindlimb nerve damage. They had often been treated with intravenous or subcutaneous calcium injections by the farmer if there was suspicion of the cow being afflicted with milk fever also.

3.7.1.4 Back injury Cows allocated into the back injury category had clinical symptoms of damage to the peripheral nerves of the lumbosacral plexus and/or structural damage to the lumbar vertebrae or pelvic bones.

3.7.1.5 Other The fifth primary category was ‘other’, which was composed of the cows that did not fit the criteria of the previous four categories.

Chapter 3: General Materials and Methods

3.7.2 Traumatic injuries Traumatic injuries, such as hip dislocation, leg fracture, damage to limb muscles or tendons were diagnosed when standard clinical examination revealed the presence of such abnormalities.

3.7.3 Neuropathies

3.7.3.1 Sciatic nerve I had developed a system of describing and grading sciatic nerve damage over many years of observation of neuropathies of recumbent cows. The research project allowed an opportunity to further explore and validate this system. I proposed that sciatic nerve damage can be differentiated into damage to the upper (proximal) and lower (distal) parts of the nerve on the basis of dysfunction as determined by sensory and motor function tests. This damage may have been from damage to the nerve roots of these parts of the nerve, or to the peripheral nerve branches along its course. I consider proximal sciatic nerve damage to have occurred when the cow showed either a unilateral increased patellar reflex (damage to the ramus communicans nerves, which innervate the hamstring group of muscles that innately resist the contraction of the quadriceps muscles when the reflex arc is stimulated (Constable, 2004)), or a medial and/or anterior tendency of the hind limb when lifted (damage to the sciatic or cranial and caudal gluteal nerves, all originating from the sixth lumbar to second sacral nerve root plexus, which control the hip abductor and extensor muscles). The proposed grading system allocates proximal sciatic damage into three levels: Grade 1 had an increased patellar reflex; Grade 2 had a moderate anterior and/or medial tendency of the hind limb when lifted, which the cow was able to correct some of the time; Grade 3 had an exaggerated anterior and/or medial tendency, which the cow was usually unable to correct. Grade 2 and 3 cases may or may not have also had an associated increased patellar reflex.

The proposed grading system for distal sciatic nerve injuries was applicable for cows that showed a proprioceptive defect when they were lifted. I classify distal sciatic nerve damage into one of four levels: Grade 1 had full sensory function at the pastern; Grade 2 had only lost sensation to the dorsal aspect of the pastern (innervated by the superficial branches of the peroneal nerve); Grade 3 had lost sensation to the dorsal and plantar pastern (innervated by the superficial branches of the peroneal and tibial nerves) but the deep pain

Chapter 3: General Materials and Methods

reflex was still present; Grade 4 had lost the deep pain reflex (involving the deeper branches of the peroneal and tibial nerves) (Getty, 1975), as well as superficial sensation to the pastern. Numbness from coldness had to be differentiated in cows without sensation to the pastern. Sciatic neuropathies are discussed in more detail in Chapter 8.

3.7.3.2 Femoral nerve Femoral nerve injuries were diagnosed by a depressed or absent patellar reflex (Smith- Maxie, 1997, Constable, 2004) and a caudal tendency of the hind legs when they tried to stand. Over many years of clinical practice, I have observed femoral nerve injuries to have four different clinical presentations: Grade 1 cows were recumbent but were able to stand and walk normally when lifted. Their patellar reflexes are usually depressed or absent but may have been normal; Grade 2 cows were able to stand independently when lifted but fell after a few steps. Their patellar reflexes were usually absent but occasionally only depressed; Grade 3 cows were unable to stand when lifted but were able to keep their legs under them in the normal sitting position; Grade 4 cows continually sat with their legs caudally (frog leg position). The patellar reflexes were always absent in Grade 3 and 4 femoral neuropathies. The four grades represent an increasing level of damage. An increase in the femoral grade score at a subsequent visit was indicative of further damage to the femoral nerves and was considered to be secondary damage. Femoral neuropathies are discussed in more detail in Chapter 7.

3.7.3.3 Obturator nerve Obturator nerve damage was diagnosed when there was a wide-based stance in the lifted position (Constable, 2004), after ruling out hip dislocation, as the obturator nerve innervates the adductor group of muscles (Getty, 1975).

3.7.3.4 Brachial/radial nerves Forelimb neuropathies were diagnosed by loss of motor function to the forelimb in the absence of other structural damage. The entire limb is affected in cases of brachial nerve damage and the limb tends to “hang” from the thoracic girdle (Constable, 2004). A severe lesion will cause analgesia of the limb below the elbow (Smith-Maxie, 1997). Cows with radial nerve damage showed a characteristic stance of a dropped elbow and partial flexion of their carpus and fetlock causing their forelimb to be dragged. There was analgesia of the

Chapter 3: General Materials and Methods dorsum of the metacarpus in cases of severe damage to the radial nerve (Smith-Maxie, 1997). In cows which stood on the non-affected front limb either spontaneously or after being lifted, radial nerve paralysis could be differentiated from brachial plexus paralysis by the ability to bear weight on the hoof when it was placed under the cow in its normal position (Parkinson et al., 2010). This was more difficult when they did not take weight on either forelimb, even with a chest strap. The flexor-withdrawal reflex (de Lahunta and Glass, 2009) was repeated in the standing position for these cases along with a re-assessment of the tone of the forelimb.

3.7.4 Compartment Syndrome Compartment Syndrome is secondary damage to the hamstring group of muscles (biceps femoris, semitendinosus and semimembranosus) from pressure from recumbency (Cox, 1982). Predictions of non-recovery using a critical threshold of creatine phosphokinase (CK) and aspartate amino transferase (AST) concentrations were developed (Clark et al., 1987). The ‘critical threshold’ was the concentration above which there was less than 5% probability of recovery. The blood results from the cows in the study were compared retrospectively against the threshold concentration based on a multiple of the enzymes’ upper normal concentrations adjusted by length of the recumbency period. A diagnosis of compartment syndrome was made when the concentrations were above relevant daily thresholds. Blood was collected from cows on one occasion, between days one and six of recumbency.

3.7.5 ‘Given up’ During the course of their recumbency, some cows became depressed and stopped eating, despite initially being bright and alert. Examination to try to determine the cause of this was undertaken by either clinical examination before they died or were destroyed or by discussions with the owners afterwards. If it was not possible to determine the cause of this depression, they were described as ‘given up’ or ‘lost the will to live’, for want of a better expressions.

3.7.6 Differentiating primary conditions from secondary conditions Any damage evident at the first examination needed to be judged as either primary or secondary damage. This could be difficult, particularly if the cows were not seen early in the

Chapter 3: General Materials and Methods

recumbency period. Damage discovered at later visits was obviously secondary damage. Every effort was made to examine cows on the first day (day zero), either by myself or a veterinarian from the Tarwin Veterinary Group, but this was not always possible. Even so, some secondary damage can occur within a few hours of the initial recumbency, so this differentiation was sometimes difficult even when the cow was seen on the first day. The cow’s history, and my clinical experience and common sense were used when conditions were allocated into primary or secondary damage. Any damage that was diagnosed at the initial visit that was not consistent with the primary cause of the recumbency was regarded as secondary damage.

3.7.7 Secondary damage Any type of secondary damage that was noted was differentiated into ‘initial’ and ‘subsequent’ damage. Initial damage was secondary damage that was apparent on the first visit and damage occurring afterwards was deemed as subsequent secondary damage.

All damage was assessed to determine if it was important from both a clinical and statistical perspective: Clinically important secondary damage was secondary damage that was judged to have contributed to the recumbency in its own right, or delayed, or prevented recovery from the original recumbency. Clinically unimportant damage was the type that was judged to not prolong the recumbency, or cause the animal to die or be destroyed. Statistically significant secondary damage was assessed using a univariable case/control comparison at day 7 against those cows without any recorded secondary damage. There were a number of types of damage where the occurrence was too low to be able to calculate a meaningful statistical comparison. These categories were considered to be ‘rare events’ and were dealt with statistically by analysis after combining them into four groups: major structural; minor structural; major disease; and minor disease.

3.8 Nursing Factors

A range of factors were recorded covering the conditions under which the cattle were nursed. These were: place of nursing; the type and hardness of the surface; the provision of shelter; weather conditions; the use of barriers; the ability of the cows to swap sides by themselves and if not, whether they were rolled manually by the carer; lifting strategies; the

Chapter 3: General Materials and Methods

use of hobbles; hygiene levels; method of transporting recumbent animals; amount and quality of the labour; and the overall ‘level of care’.

Cows were often moved from the place of their initial recumbency and some were moved to several different nursing sites. The nursing factors for each location and the time period between each move were recorded.

3.8.1 Nursing score During the study period, I defined what I considered to be the optimum level of nursing care for recumbent cows in southern Victorian dairy areas. This is shown in Table 3.1. I complied this table, based on a variety of sources (Andrews, 1992, Belloli et al., 1996, Harwood, 2003, Huxley, 2006, Huxley et al., 2010, Parkinson et al., 2010), and from my experience over many years of clinical practice.

I recorded the conditions the recumbent cows were nursed under and compared them to the proposed optimum standard of care. This was difficult because there were a large number of components of nursing care recorded and their implementation varied considerably between farms and often within farms. To be able to measure the influence the overall level of care had on recovery, in as an objective manner as possible, I developed a four-tiered grading system (nursing score) to summarize the conditions under which the cows were cared for, relative to the optimal nursing conditions. The nursing score reflected the effectiveness of the implementation of the proposed nursing requirements. It took into consideration both the degree of compliance for each nursing component and the relative period of time that the requirements were fully implemented. The definitions of the four nursing scores that were used are shown in Table 3.2.

The increasing scores reflect a decreasing compliance with the optimum standard. A separate score was allocated for the ‘initial’, ‘subsequent’ and ‘overall’ nursing periods. The initial period was defined as the conditions the cows were nursed prior to the first visit. This was assessed on the basis of conditions observed at my first visit and on the history obtained from the farmers. The subsequent period was the period of time directly that I observed. The subsequent nursing score was allocated at the end of the nursing period to reflect an average of the observed conditions over the period as conditions could have changed during that time. The overall nursing score was a weighted average of the initial

Chapter 3: General Materials and Methods

and subsequent nursing scores, reflecting the relative duration of time under each period. The nursing scores for the three nursing periods were allocated at the conclusion of each period when all of the nursing factors were known but without consideration of the outcome of the cow. Due to the range of variations in nursing conditions compliance could only be allocated into one of four quartiles as it was not possible to assign a precise numerical value on the nursing quality. The limitations of this methodology are discussed in Chapter 6.

The four nursing scores were combined into two categories for some analyses, being ‘satisfactory’ (excellent and good) and ‘unsatisfactory’ (very poor and poor).

3.9 Outcomes The status of the cows was assessed at day 7 and at their conclusion. Day 7 outcome was regarded as the primary outcome as it was a defined time period that gave cows a ‘reasonable’ length of time to recover. Cows that were not able to stand and walk independently at this stage were regarded as ‘failures’.

Day 7 progress was recorded as ‘able to stand’, ‘walk if lifted’, ‘stand if lifted’, ‘still down’, ‘euthanased’ or ‘died’. Some cows continued to be nursed after the seventh day.

Final outcome may have been different to day 7 outcome for those cows that were continued to be nursed after the seventh day. Final outcome was compared against day 7 outcome to see how many cows recovered if given extra time.

Outcome had two categories: recovered or death

1. Recovered was defined as being able to consistently stand independently and walk around for at least the following two days

2. Death was either from: euthanasia, which was at the farmers’ discretion, unless I considered the animal was suffering welfare issues; or from an acute medical condition where they were found dead

For the cows that recovered, records were not kept as to whether they were milked during the current season, or whether they kept for later breeding or were sold.

Chapter 3: General Materials and Methods

3.10 Statistical analysis A case cow was defined as not recovered and a control cow as recovered. Logistic regression and the odds ratio (OR), 95% confidence interval (CI) and Wald P value were used to measure the strength of association between risk factors and case/control status. If any cell in a 2 X 2 table was zero, 0.5 was added to each cell frequency before the calculation to report an adjusted odds ratio and 95% CI (Fleiss et al., 2003). The Cochran-Armitage test for trend (Armitage, 1955, Cochran, 1954) was used to test for a linear component of trend between the relevant score or grade and the proportion of cows with a given binary outcome. StatXact software was used to calculate the exact P value for the Cochran- Armitage test for trend. StatXact 10 (Cytel, Cambridge, MA) and WinPepi 11.48 (Abramson, 2011) software were used for the analyses. Two-sided P values < 0.05 were regarded as statistically significant.

The various statistical methodologies for the different sections are described in the relevant chapters.

Chapter 3: General Materials and Methods

Table 3.1. Proposed optimum standard of care for recumbent cows in southern Victorian dairying areas Component Description Treatment Appropriately treated for the primary cause of the recumbency Appropriately treated for any secondary conditions following the recumbency Location For recumbent cows: • Cared for in a small, sheltered area within a shed For cows that are unable to stand unassisted but can walk after being lifted: • kept away from slippery surfaces • isolated from other cattle • lifted once or twice daily • closely monitored Bedding Cared for on deep, soft bedding of suitable material: • 40 - 50 cm of hay, straw • 20 - 30 cm of sawdust, rice hulls or sand • or equivalent substrate Weather conditions Protected from adverse weather conditions, including excessive cold and heat Barriers For recumbent cows: • barriers to restrict cows crawling more than 3 - 4 metres • barriers to prevent cows crawling off the suitable bedding For cows that can stand after being lifted but unable to walk: • barriers to prevent walking when standing Rolling For cows that are unable to swap sides by themselves: • rolled off dependent leg several times daily Lifting Cow only lifted if: • ‘effective’, which is the ability for the cow to take some of her own weight after being lifted and is not hanging from the lifting clamp or within the frame • ‘supervised’ by the carer so the cow can be lowered when observed to be no longer standing effectively Hygiene Clean and dry conditions are provided Area is regularly cleaned to prevent build-up of manure, urine and moisture Level of care High levels of ‘tender love and care’ provided at all times Adequate levels of labour provided Feed and water Access to good quality feed at all times Adequate provision of suitable drinking water Udder care Milking is optional unless leaking milk Teat disinfection twice daily Moving between location Moved in a way to avoid inflicting further damage, such as by: • front-end loading bucket • “carry-all”

Chapter 3: General Materials and Methods

Table 3.2. Criteria of the nursing scores used to assess compliance to the proposed optimum nursing standards for recumbent cows in Southern Victoria Nursing score Compliance with the optimum standard of care One Excellent compliance Nursing requirements were implemented with more than 75% effectiveness or were fully implemented for more than 75% of the time Two Good compliance Nursing requirements were implemented with 50 - 75% effectiveness or were fully implemented for 50 - 75% of the time For example: • In paddocks when weather conditions were favourable, the paddocks were flat and the ground soft with some ‘give’ in it • nursing compliance was ‘poor’ for part of the time and ‘excellent’ for part of the time so overall compliance was averaged to ‘good’ Three Poor compliance Nursing requirements were implemented with only 25 - 49% effectiveness or were fully implemented for only 25 - 49% of the time For example: • outside in cold and wet conditions, but not extremely so • in the paddock where the ground was cold and wet or hard • in sheds on dirt or gravel with only a token amount of soft bedding • cows crawled off suitable bedding Four Very poor compliance Nursing requirements were implemented with less than 25% effectiveness or were fully implemented for less than 25% of the time For example: • very wet, muddy and cold conditions • on very hard surfaces, such as concrete or gravel • allowed to crawl around unrestricted over more than 3 - 4 metres • found to be lying in heavily soiled areas for more than one day • obvious neglect and lack of care, such as lying in lateral recumbency for extended periods

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

Chapter 4. Musculo-Skeletal Examination of the Recumbent Cow

4.1 Introduction The musculo-skeletal examination of the recumbent cow involves assessment of the structures of their locomotive system and includes bones, joints, muscles, ligaments, tendons and nerves. Neurological examination is part of the musculo-skeletal examination and techniques for different animals are covered in various reference textbooks (Constable, 2004, de Lahunta and Glass, 2009) but vary depending on the species and if the animal is ambulatory or recumbent.

I consider that there are limitations in these musculo-skeletal protocols for recumbent cattle and I have developed some additional tests to enhance the information gained from the examination.

Over a number of years, in my discussions with many cattle veterinarians, from many different countries, I consider that musculo-skeletal examinations and in particular, full neurological examinations on recumbent cattle, are done poorly. This is often due to the difficulties they impose. In particular, the patellar reflex test is not commonly performed in cattle, despite it being a standard part of a small animal neurological examination, and many recumbent cattle are not lifted during the examination, which limits the ability to assess posture and postural responses. Failure to do these tests limits the completeness of the examination, compromising the diagnosis that is reached. I will describe a musculoskeletal examination of a recumbent cow that lacks patellar reflex and lifting assessments as an ‘abbreviated’ technique. This is the type of examination I have found that many cattle veterinarians perform.

This chapter describes the protocols that I used when I examined the recumbent cows. It also describes the differences between the method proposed in this chapter, current techniques described in the literature (Constable, 2004, de Lahunta and Glass, 2009) and common ‘abbreviated’ techniques. The findings from a study of 218 downer dairy cows using these my techniques are compared to the probable diagnoses that would have been made using ‘abbreviated’ examination methods, to highlight the differences between the two techniques.

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

4.2 Proposed Musculo-Skeletal Examination Technique for Down Cows This examination technique applies to recumbent cattle that are bright, alert and responsive and is in addition to any medical examination that would normally be performed. It is aimed at assessing the musculo-skeletal system including bones, joints, muscles, ligaments, tendons and nerves. I have developed this technique and refined it over many years, based on my experience and on a number of various reference articles and text books (Constable, 2004, de Lahunta and Glass, 2009, Divers, 2004, Getty, 1975, Parkinson et al., 2010). I propose that this method is a comprehensive musculo-skeletal examination and should be considered to be the ‘gold standard’ for recumbent cows.

1. Visual observations in the recumbent position:

a. The position of the recumbent cow is observed in regard to whether she is in a sternal or lateral position and if lateral, attempts are made to right the cow into the sternal position and noted if that position can be maintained

b. The posture in the sternal position is assessed for any variations from normal

c. The recumbent animal is encouraged to try to stand and the strength of the motor response and any limb deviations from the normal standing motion are noted

2. Examination in the sternal position:

a. Visualisation and palpation of the vertebral column is performed with the cow sitting in sternal position on one side and repeated when rolled onto the opposite side. The curvature of the spine, when carefully viewed from above, is assessed to check against the expected normal curvature. Any abnormal dorsal spinal process positions are noted. The positions of the lateral spinous processes relative to their neighbouring processes are also noted when sitting on one side and re-examined when rolled onto the other side to note if their positions have changed

b. The main lumbar and pelvic muscles are palpated for swellings or pain

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

c. The lumbo-sacral ligament is assessed for increased laxity by rocking on both tuber coxae in a dorso-ventral direction with the cow in the normal sitting position

d. The ‘superficial’ flexor-withdrawal reflex is performed to assess response at the dorsal and palmer surfaces of the pastern (Figure 4.1), which are innervated by the superficial branches of the peroneal and tibial nerves, respectively (Getty, 1975)

i. The skin of the dorsal and plantar pastern is stimulated with an 18 gauge hypodermic needle to provoke a withdrawal response by the limb and a conscious acknowledgment by vocalisation or head movement

ii. If no reaction is recorded when stimulating both surfaces, a stronger stimulus, such as forceps or an electric cattle prodder may be used to ensure the negative response is accurate, particularly if the limb is cold from adverse conditions

e. Anal tone is assessed by pinching the anal skin with forceps. The normal response is for the anal sphincter to tighten and the tail ventroflex (de Lahunta and Glass, 2009)

f. The tail is moved by hand to assess if its tone is normal or flaccid

3. Examination in the lateral position:

a. The hindlimb is examined:

i. Visually and by palpation for fractures, dislocated or swollen joints, damaged tendons or muscles

ii. Muscle tone of the hindlimb is assessed to note if it is normal or flaccid

iii. The hip is manipulated through its range of normal movement for evidence of crepitus or abnormal position

iv. The patellar reflex is performed using hoof testers or a similarly suitable implement to strike the patellar ligament firmly. The limb

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

needs to be held in a reasonably neutral position with the stifle forming an angle of approximately 90 degrees. The normal reflex induces a moderate extension of the stifle (Constable, 2004)

v. The cranial tibial (peroneal nerve) and gastrocnemius (tibial nerve) reflexes are not present in all normal cattle, so are not worth performing (de Lahunta and Glass, 2009)

vi. The ‘deep’ flexor withdrawal reflex is tested by firmly squeezing the inter-digital area with hoof testers to induce a withdrawal response

b. The forelimb is examined:

i. Visually and by palpation for fractures, dislocated or swollen joints, damaged tendons or muscles

ii. Muscle tone of the forelimb is assessed to note if it is normal or flaccid

iii. The ‘superficial’ withdrawal reflexes are tested by stimulating the pastern with an 18 gauge hypodermic needle over the regions innervated by the radial, median and ulnar nerves (Figure 4.2)

iv. The ‘deep’ flexor withdrawal reflex is tested by firmly squeezing the inter-digital area with hoof testers to induce the withdrawal response

v. The biceps and triceps reflexes are unreliable and not recommended (de Lahunta and Glass, 2009)

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

Figure 4.1. Major nerve branches of L6-S2 nerve plexus, adapted from Smith-Maxie (1997)

Figure 4.2. Sensory distribution of forelimb nerves in cattle, adapted from Smith-Maxie (1997)

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

4. The recumbent animal is lifted by suitable equipment, such as a tractor and a lifting device, such as Bagshaw hip clamps:

a. Posture is assessed and any unusual limb directions or a tendency for the hindquarters to lean are noted

b. Postural reactions are assessed, which is limited in large animals but proprioceptive defects can be readily assessed in this lifted position

c. Muscle tone is assessed for each limb by:

i. Noting the amount of weight borne by each limb

ii. Flexing and extending the limbs manually to assess if the limb is flaccid or has normal tone, which I find easier to judge when the animal is in the raised position due to the extra weight of the limb

d. If non-weight bearing on forelimbs when lifted, especially when lifted with hip clamps, I recommend placing a suitable strap under the sternum to support the fore quarters and if the cow continues to non-weight bear, repeating the following tests on the forelimbs:

i. The flexor-withdrawal test and note made if the limb is partially or fully withdrawn and if it returns to the normal standing position

ii. Muscle tone of the upper and lower portions of the forelimb and compared to the other forelimb

Blood is taken if the animal has been recumbent for 24 hours to six days. Creatinine Phosphokinase (CK) concentrations are analysed and compared to threshold levels above which the probability of recovering is less than 5% (Clark et al., 1987).

4.2.1 Mechanism of the flexor-withdrawal reflex The withdrawal-flexor reflex is evaluated in recumbent cattle by squeezing the skin between the claws with thumb and forefingers or by forceps or pliers (Constable, 2004). The normal response is to for animals to pull the leg away from the stimulus and acknowledge it by looking or vocalising. Some cattle may need the use of a stronger stimulus, such as the judicious use of an electric cattle prodder to induce the response. The ability to withdrawal

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

the forelimb requires spinal segments C6-T2 and the radial nerve to be intact whereas for the hindlimb, spinal segments L5-S1 and the sciatic nerve are required. For animals to acknowledge the stimulus, the nociceptive pathway through the spinal cord to the cerebrum needs to be functioning (Constable, 2004).

Spinal cord lesions above the fourth lumbar vertebra (L4) will have normal flexor-withdrawal reflexes but lack nociception, whilst peripheral nerve lesions will involve loss of both the spinal reflexes and nociception (de Lahunta and Glass, 2009).

I further refine the flexor-withdrawal reflex in the hindlimb by assessing the dorsal and plantar aspects of the pastern separately (Figure 4.1), in addition to squeezing the inter- digital area as advocated by (Constable, 2004). I use an 18 gauge hypodermic needle to stimulate the skin of the two halves of the pastern. The dorsal pastern is innervated by the peroneal nerve and the plantar pastern by the tibial nerve (Vaughan, 1964). I call this the superficial flexor-withdrawal reflex. When the inter-digital area is squeezed by hoof testers, I refer to it as the deep flexor-withdrawal reflex.

I have also further refined the flexor-withdrawal reflex in the forelimb into superficial and deep reflexes: The superficial withdrawal reflex is assessed by stimulating the skin of the four quadrants of the pastern with an 18 gauge hypodermic needle. The radial nerve supplies sensation to the dorso-medial pastern, the ulnar nerve supplies the lateral pastern and the median and ulnar nerves supply the plantar pastern, as shown in Figure 4.2, which is adapted from (Smith-Maxie, 1997). The inter-digital area is then squeezed firmly with hoof testers to assess the deep flexor-withdrawal reflex. These tests are performed in the recumbent position. If the animal fails to bear weight normally on the forelimbs when lifted, the flexor-withdrawal reflex is repeated in the standing position by either stimulating the caudal metacarpus with an electric cattle prodder or squeezing the inter-digital area with hoof testers. The normal response is for the animal to withdraw the leg away from the noxious stimuli by flexing the shoulder, elbow, knee and fetlock. The hoof should then return to the normal standing position. This test is referred to as the ‘standing flexor- withdrawal’ test.

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

4.2.2 Mechanism of the patellar reflex The patellar reflex requires spinal cord segments L4 and L5 and the femoral nerve to be functioning normally. It may also be depressed in ruminants with myonecrosis from recumbency or white muscle disease (Constable, 2004). It can be exaggerated if the sciatic nerve is damaged, due to weakness of the hamstring muscle group that opposes the stifle extension when the reflex is tested. It may be bilaterally increased with an upper motor neurone (UMN) lesion (Constable, 2004).

4.3 Diagnosis of Neuropathies of Recumbent Cows The various conditions were diagnosed by the following findings:

Back fracture: The literature suggests that back fracture above L4 present with flaccid paralysis, an absence of nociception, negative anal and tail tone reflexes, exaggerated patellar reflexes bilaterally and normal flexor-withdrawal reflexes of the hindlimbs (Constable, 2004, de Lahunta and Glass, 2009). I have noted that back fracture in cattle can present in a variety of ways, dependant on the amount of spinal cord damage present at the time of examination: some can present as described in the literature, although I have not seen any with bilateral increased patellar reflexes. I have observed that they usually present with depressed or absent patellar reflexes, despite the damage often being higher than L4. Some have a reasonable amount of motor function when lifted, rather than the expected total flaccid paralysis. Most will have displacement of either the lateral and/or dorsal spinous processes. These changes can be subtle with a variation of as little as only 1 cm from the normal position. If the zygo-pophyseal joints are fractured the lateral processes will often rotate relative to each other when the cow is rolled from side to side. Any variations must be differentiated from old fractures of the processes, which do not change their orientation to their neighbouring lateral processes when the cow is rolled. The curvature of the spine may change as they are rolled from side-to-side as the segments above the fracture site move independently to the segments below, consistent with damaged zygo-pophyseal joints. I consider that cattle that present with changes in the orientation of their lateral and/or dorsal spinous processes when rolled should be euthanased, even if they do not show all of the classic signs of back fracture at the time of the examination. These changes can only occur if the zygo-pophyseal joints are fractured

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

and this instability will result in ongoing damage to the spine, leading to total paralysis over the following days, if it is not already apparent.

Sciatic nerve presents as “rear limb weakness and knuckling of the fetlock” and the patellar reflex may be normal or increased (Constable, 2004). I believe that this definition is too limited, as some cases do not present with knuckling of the fetlock. I consider that sciatic nerve damage can have a variety of presentations, dependent upon the location and extent of the damage to the nerve. The sciatic nerve originates from the L6, S1 and S2 nerve roots, passes immediately ventral to the sacrum before combining into the sciatic nerve bundle. It gives off numerous branches to innervate the pelvic and caudal thigh musculature before dividing into the peroneal and tibial nerves at the mid-thigh level. The peroneal nerve innervates the anterior aspect of the lower limb and the tibial nerve innervates the caudal aspect (Getty, 1975). In cases of sciatic nerve injury at the spinal level (back injuries) or intra-pelvic level (calving paralysis), the axons damaged may be part or all of any or all of the three nerve roots:

• In cases where all of the axons are damaged a complete flaccid paralysis of the hind limb will occur with complete loss of sensation to the distal limb (Divers, 2004, Smith-Maxie, 1997)

• In cases of partial sciatic nerve injury, the clinical presentation will depend on how many and which axons of the sciatic nerve roots are damaged, as some axons make up the nerve branches that terminate in the pelvic muscles, some form the rami musculares that terminate in the caudal thigh musculature, some form the peroneal nerve and others the tibial nerve

o When the axons of the pelvic musculature have been damaged, the cow will display an anterior and/or medial hindlimb tendency when lifted due to an inability to abduct and/or extend her hip (Galabinov, 1966)

o If the caudal thigh muscle innervation has been affected, the patellar reflex will be exaggerated, often uni-laterally, due to weakness in the hamstring muscles (biceps femoris, semimembranosus and semitendinosus), as these muscles oppose the extension of the stifle induced by the reflex (Constable, 2004)

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

o Damage to the axons that form the peroneal nerve will present with knuckling of the fetlock when the cow is lifted, due to digital extensor weakness and loss of proprioception, with or without loss of sensation to the dorsal pastern (Constable, 2004, Smith-Maxie, 1997)

o Damage to the axons that form the tibial nerve will present as loss of sensation to the plantar aspect of the pastern (Vaughan, 1964)

Tibial paresis is a distinct neuropathy where the animal has paresis rather than recumbency. It presents with hyperflexion of the hock due to lack of extension of the gastrocneumius muscle, innervated by the tibial nerve. The fetlock has a corresponding hyper-flexion, which presents as a forward knuckling but the hoof remains in contact with the ground (Parkinson et al., 2010, Vaughan, 1964). Skin sensation to the plantar aspect of the metatarsus and fetlock is lost with severe damage (Parkinson et al., 2010). Concurrent tibial paresis can occur in cows recumbent from other neuropathies and they display the characteristic posture on one or both hindlimbs when they are lifted. The peroneal nerve is not damaged in these cases as the fetlock is not knuckled over with its dorsal aspect in contact with the ground.

This study proposes differentiating sciatic nerve damage into ‘proximal’ and/or ‘distal’ damage, whereby proximal refers to the function of the sciatic nerve and its branches prior to the sciatic nerve bifurcating into the peroneal and tibial nerves. This includes the cranial and caudal gluteal nerves and the rami musculares. These branches innervate the pelvic and caudal thigh musculature. The distal parts of the sciatic nerve are the peroneal and tibial nerve branches, which innervate the structures distal to the stifle. The damage to the sciatic branches may have occurred at the spinal or intra-pelvic level or along the peripheral nerve itself so this classification does not relate to where the damage has occurred, rather to the functional parts of the nerve that have been affected. This is discussed in more detail in Chapter 8.

Femoral nerve injury was diagnosed by a depressed or absent patellar reflex in association with a caudal tendency of the hindlimbs. The clinical presentations ranged from the cow being able to walk normally after being lifted, through to the most severe form where the cow was unable to sit in the normal sternal position as her hindlimbs were constantly extended caudally in the ‘frog-leg’ position. 54

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

I have found that brachial and radial paralysis cases are best diagnosed by lifting the animals, if they are unable to stand, and observing their posture and postural reactions. This is because I have noted that all of the cases had normal flexor-withdrawal reflexes when I assessed them in the recumbent position. Mild to moderate damage to the brachial plexus or radial nerve caused motor dysfunction but sensory function to the pastern was retained. When they were lifted into the standing position, the abnormal postural response of the affected forelimb was observed. The flexor-withdrawal reflex for the entire limb was negative for brachial plexus paralysis cases when it was repeated in the standing position. Cows with radial nerve paralysis could withdraw their forelimb by flexing their shoulder and elbow but they were unable to extend the knee and pastern. Cows with radial nerve paralysis can support their weight on the forelimb when it is placed under them in the normal position but cows with brachial plexus paralysis are unable to do so (Parkinson et al., 2010).

I have observed a large number of cows that have refused to stand on their forelimbs after being lifted with hip clamps. Many of these cows would then stand correctly after a chest strap was used in addition to the hip clamp, indicating that the function of the forelimbs was normal. Others would stand correctly on one forelimb and display clinical signs of radial nerve or brachial plexus paralysis of the other limb, allowing a diagnosis to be readily made. Some however, would refuse to bear weight on both forelimbs even when the chest strap was used. This could be due to a psychological ‘refusal to stand’ or either radial nerve or brachial plexus paralysis. For such cows, a more detailed examination needed to be performed whilst in this lifted position, by re-assessing limb tone and repeating the flexor- withdrawal reflex. Cows with normal limb function had full limb tone and the ability to fully withdrawal their limb when stimulated with a noxious stimulus, such as a cattle prodder applied at the fetlock. These cows did not stand on their forelimbs, presumably, for behavioural reasons. Cows with radial nerve paralysis had normal tone through their shoulder and elbow and could flex their shoulder and their elbow when the flexor- withdrawal reflex test was repeated, unlike those with brachial plexus paralysis, which had a complete flaccid paralysis of the forelimb and a negative withdrawal reflex when tested in the standing position. Cows with a high radial nerve injury will also have lost extension function of the elbow, in addition to the lower limb. I have observed that all of the cows

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

that I diagnosed with either radial nerve or brachial plexus paralysis after being lifted, had normal flexor-withdrawal reflexes when tested in the prone position. I postulate that the different response to the flexor-withdrawal reflex in the standing versus recumbent position was due to the extra motor function required to lift the weight of the leg against gravity, in the standing position.

4.4 Results From the 218 downer cows in this study there were 374 types of secondary damage documented using my examination methods. Table 4.1 compares these findings with the likely diagnoses that would have been made by an ‘abbreviated examination’, where patellar reflexes were not assessed and the cows were not lifted, as commonly occurs when cows are examined in the field by many veterinarians.

It is probable that 121/374 (32%) of the secondary damage would not be diagnosed by the abbreviated examination technique. If CK concentrations were also not analysed a further 61 diagnoses would have been missed, resulting in 182/374 (49%) conditions being undiagnosed.

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

Table 4.1. Secondary damage diagnosed in 218 downer cows by the examination technique proposed in the study compared to likely diagnoses if the cows were not lifted and patellar reflexes were not performed (abbreviated technique) Group Diagnosis Full examination Abbreviated technique technique1 n n Forelimb neuropathies Brachial plexus paralysis 23 0 Radial nerve paralysis 15 0 Hindlimb neuropathies Femoral nerve 47 0 Sciatic nerve 21 1 Tibial nerve 16 0 Structural Compartment syndrome 61 61 Hip dislocation 30 30 Bed sores 23 23 Muscle atrophy 21 21 Lifting damage 15 15 Strained/torn muscle 9 9 Joint infections 6 6 Adductor muscle and/or obturator nerve 5 5 Sacro-iliac damage 4 4 Back fracture 2 2 Stifle rupture 1 1 Organ Exposure 18 18 Aspiration 10 10 Mastitis 5 5 Scours 3 3 Pneumonia 3 3 Other infection 4 4 Heart failure 1 1 Other ‘Given up’ 31 31 Undiagnosed conditions 0 121 Total 374 374 1Cows are not lifted and patellar reflexes are not assessed.

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

4.5 Discussion Posture and postural responses can only be assessed in recumbent cattle when they are lifted. Many recumbent cattle are not lifted as part of their musculo-skeletal examination due to logistical problems, such as a lack of suitable equipment, from time constraints or lack of knowledge as to its importance. Many veterinarians do not assess patellar reflexes in recumbent cattle despite routinely performing them in small animal neurological examinations. A diagnosis of compartment syndrome requires CK assays. If these three components of a complete examination are not performed important clinical symptoms will be missed on many occasions, leading to incomplete diagnoses. The sciatic neuropathies that present with an increased patellar reflex and/or postural abnormalities will be missed. Only the severe presentation of sciatic injury with loss of the flexor-withdrawal reflex would be diagnosed. Femoral neuropathies will be missed as an absent or depressed patellar reflex is diagnostic. With regard to forelimb neuropathies, both radial nerve and brachial plexus paralyses will be under-diagnosed as I have found that they usually presented with normal sensation to the pastern despite reduced motor function, which is in contradiction to the literature (Constable, 2004, Divers, 2004, Vaughan, 1964). They regularly have a normal flexor-withdrawal reflex in the recumbent position and it is only deficient in the standing position. The difference is probably because of the extra motor function required to withdraw the weight of the forelimb against gravity when standing. Muscle tone is more accurately assessed in the lifted position for the same reason. Clinical cases usually do not present with a total paralysis with complete loss of sensory and motor function but rather with degrees of loss of nerve function.

Half of the different types of secondary damage found in the 218 downer cows examined in this study probably would not have been diagnosed if patellar reflexes were not performed, the cows were not lifted and CK concentrations not analysed. This highlights the importance of such procedures when examining downer cows.

The examination technique for recumbent cows described in the literature (Constable, 2004, de Lahunta and Glass, 2009) included patellar reflex testing and lifting, which would give more accurate diagnoses than the abbreviated technique. However, I still do not consider it to be as complete as my technique: they advocate performing flexor-withdrawal reflexes on the hindlimb by squeezing the inter-digital region with fingers or pliers, which is

Chapter 4: Musculo-Skeletal Examination of the Recumbent Cow

equivalent to my ‘deep’ flexor-withdrawal reflex. A positive withdrawal of the limb indicates normal function of the sciatic nerve and its spinal segment (Constable, 2004) However, the cows with Grade 1-3 distal sciatic nerve damage had damage to their sciatic nerve despite a positive deep flexor-withdrawal reflex, and thus by Constable’s (2004) definition, would have been misdiagnosed. Similarly, all of the cows with brachial and radial nerve paralysis in this study, which had normal flexor-withdrawal reflexes when assessed in the recumbent position, could have been missed as Constable (2004), and de Lahunta and Glass (2009) do not describe repeating this test in the standing position. Their inability to bear weight on their forelimb when lifted may have been wrongly ascribed to a psychological ‘refusal to stand’. Constable (2004) recommends patellar reflex testing as part of his examination but does not mention femoral nerve damage in adult cows. This could lead the practitioner to attribute a negative patellar reflex to causes other than femoral nerve damage, perhaps myonecrosis from recumbency.

4.6 Conclusions A comprehensive musculo-skeletal examination must be performed on recumbent cows to maximise the clinical findings. This includes CK concentration analysis, patellar reflex testing and lifting the cow to assess posture and postural responses. On some farms suitable lifting equipment is not available and in such cases, the limitations of the compromised examination must be understood. When the equipment is available the extra information obtained will more than offset the extra time and effort required to lift the cow.

Chapter 5: The Importance of Secondary Damage in Downer Cows

Chapter 5. The Importance of Secondary Damage in Downer Cows

5.1 Introduction Downer cows can be defined as cows that are “down in sternal recumbency for more than 24 hours with no evidence of systemic illness” (Cox, 1981), as opposed to down cows, which are cows that are recumbent for any reason and time period. They are a commonly recognized problem around the world but their occurrence is hard to determine due to the different interpretations of the term. An Australian survey (Watson and Watson, 2012) showed 89% of dairy herds across Australia had recumbent cows in the previous twelve months, of which approximately two-thirds had recovered within the first 24 hours, giving the average occurrence of downer cows as 2.88 cows per herd. This varied from a mean of 1.62 - 4.69 cows per herd across the different dairying regions of Australia. An average of 33% of these cows survived. Unfortunately, the data was collected on a ‘per herd’ basis and whilst it was broken down into ‘small’ (<150 cows), ‘medium’ (150-300 cows), ‘large’ (301- 500 cows) and ‘extra-large’ (>500 cows) herd sizes, the incidence of downer cows was not analysed on a ‘per cow’ rate. A study of Minnesota dairy herds that looked at cows recumbent for more than 24 hours quoted an incidence of 21.4 cases per 1,000 cow years in 1986 (Cox, 1988). A survey in one study of 2,705 lactations in New York State revealed a proportion of downer cows of 1.1% in the first 30 days post-partum, with the risk increasing five-fold if the cow suffered dystocia or clinical milk fever (Correa et al., 1993).

There are a large number of possible diagnoses for a persistently recumbent cow (Van Metre, 2001). These can be grouped into four broad categories: metabolic; musculo- skeletal; acute systemic illness; and ‘other’.

Historically, downer cows were associated with many conditions, including: Metabolic Complex Parturient Paresis; hypophosphataemia; hypomagnesaemia; hypokalaemia; hyper- and hypo-adrenocortical activities; cerebral oedema; albuminuria; renal disease; hepatic changes; muscle degeneration; and physical injuries (Kronfeld, 1970). Later authors concluded that the downer cow syndrome was a complication of post-parturient hypocalcaemia (milk fever) (Blood et al., 1979) where cows were unable to stand following treatment for milk fever due to traumatic injury to the leg muscles. Other researchers considered secondary damage to the muscles and nerves of the hind limbs to be the cause of downer cows (Cox, 1988), as shown by the fact that they could usually stand on their

Chapter 5: The Importance of Secondary Damage in Downer Cows

front legs if lifted with a suitable device. However, there is little information available in the literature on the level of secondary damage or its importance in downer cows.

The relative importance of the primary cause of the recumbency and the secondary complications that arise from it needs to be known to better understand the pathogenesis of downer cows. This will ensure that they are treated and managed correctly.

The management of recumbent cows is an important animal welfare issue for the dairy industry as they could be suffering unnecessarily if not managed appropriately.

The aims of this part of the study were to examine a wide variety of downer cows under field conditions, record the primary reasons for their recumbency, any secondary damage that occurred, their outcome and assess the influence of the primary conditions relative to the secondary complications on their fate.

5.2 Materials and Methods Field studies of recumbent dairy cows were conducted in South Gippsland during two three-month periods in the winter calving months of 2011 and 2012. Cows were included in the study if they were bright, alert and responsive; had been recumbent for at least one day; and an adequate history was available. Calves and yearlings were excluded as were any cows with a history of recumbency in the previous 30 days. Cows were initially attended by a veterinarian as soon as possible after the recumbency, ideally on the first day. Any cow that was not still recumbent on the following day was excluded from the data set. The cows were thoroughly examined and the farmers were closely questioned on the cows’ history to determine the cause of the recumbency and to detect any secondary damage.

Thorough medical and musculo-skeletal clinical examinations were performed on each cow at each visit to detect damage and judge progress. The musculo-skeletal examination included:

• Assessment of the spinal column for fractures

• Assessment of the limbs for damage to joints, tendons, ligaments and muscles

• Nerve function assessment by:

Chapter 5: The Importance of Secondary Damage in Downer Cows

o Flexor-withdrawal reflex, patellar reflex and muscle tone assessment in the recumbent position

o Observation of postural responses when they tried to stand and when they were lifted using chest straps for cows that failed to bear weight on the forelimbs when lifted with lift clamps

o Flexor-withdrawal reflex and muscle tone assessment were repeated in the elevated position

• Blood samples were taken for serum analysis of Creatinine Phosphokinase (CK) and Aspartate Amino Transferase (AST) concentrations

Musculo-skeletal abnormalities and medical conditions were diagnosed using accepted, standard clinical examination methods but the diagnoses of some specific musculo-skeletal conditions are listed below:

• Displacement with rotation of dorsal or lateral spinous processes indicated a vertebral fracture

• Sciatic nerve dysfunction was indicated by a number of symptoms, depending on which branches of the nerve were involved and its severity: Mild damage was indicated by increased patellar reflex without other sciatic signs and/or by a proprioceptive deficit when lifted without loss of sensation to the pastern. Moderate and severe damage was indicated by decreased sensations of the plantar and/or dorsal pastern with a proprioceptive deficit when lifted and/or by a tendency for an anterior/medial displacement of the leg when lifted. Peroneal nerve damage was included in this group of sciatic nerve dysfunction

• Femoral nerve dysfunction was indicated by decreased or absent patellar reflex and a tendency for a caudal displacement of the hindlimbs when trying to stand. Femoral dysfunction was graded into two groups, classified as mild and severe: Mildly affected cows could stand and/or walk after being lifted; whereas severe ones could not

• Brachial plexus paralysis was indicated by flaccid paralysis and negative flexor- withdrawal reflex, which were assessed in both the recumbent and raised positions

Chapter 5: The Importance of Secondary Damage in Downer Cows

• Radial nerve paralysis was indicated by flaccid lower limb function and a proprioceptive deficit when lifted but normal upper limb function

• Tibial paresis was diagnosed by a mild over-flexion of the hock, elongation of the gastrocneumius area and a slightly flexed fetlock but with the claw in a normal position

Compartment syndrome is an ischaemic myo-necrosis, usually of the hamstring group of muscles (biceps femoralis, semitendinosus and semimembranosus) caused by pressure from being recumbent on hard surfaces (Van Metre, 2001). It was diagnosed when CK concentration was above the threshold level, a time adjusted multiple of the upper normal CK range, shown in Table 5.1. A previous study indicated less than 5% chance of recovery above these levels (Clark et al., 1987).

Table 5.1. Critical CK levels relative to days recumbent in downer cows Days recumbent Times normal Critical CK level of Critical level for Clarka (U/L) this studyb (U/L) 0.5 33 12,200 8,250 1 50 18,600 12,500 2 44 16,300 11,000 3 38 14,000 9,500 4 29 10,900 7,250 5 23 8,500 5,750 6 17 6,200 4,250 7 10 3,900 2,500 aNormal reference range: 0 – 370 U/L (Clark et al., 1987). bNormal reference range: 30 – 250 U/L (Veterinary Clinical Pathology, The University of Melbourne).

‘Non-alertness’ was defined as cows that had been bright, alert and responsive deteriorating to a mental state where they became dull and unresponsive with depressed appetite.

Exposure was defined as depressed cows with sub-normal body temperatures (less than 36.5 degrees centigrade) due to being subjected to very cold weather.

On the basis of the initial attending veterinarian’s clinical examination and farmer history, the cows were allocated into one of five broad primary groups: post-parturient hypocalcaemia (milk fever); protein-energy deficiency (Parkinson et al., 2010); calving

Chapter 5: The Importance of Secondary Damage in Downer Cows

paralysis; back injury; and ‘other’. The criteria for these categories are discussed in Chapter 3, General Materials and Methods.

On the basis of clinical examination, any damage that was diagnosed at the initial visit that was not consistent with the primary cause of the recumbency was regarded as secondary damage. Any damage diagnosed at subsequent visits that was not apparent at the initial visit was regarded as secondary damage.

All damage was assessed to determine if it was important from a clinical and statistical perspective. Clinically important secondary damage was regarded as secondary damage that contributed to the recumbency in its own right or delayed or prevented recovery from the original recumbency. Conditions considered to be important clinically were:

• Brachial plexus paralysis

• Radial nerve damage

• Mild and severe femoral nerve damage

• Moderate and severe sciatic nerve damage

• Hip dislocation

• Compartment syndrome

• Muscle atrophy

• Severe presentations of diseases such as mastitis, pneumonia and diarrhoea

• Severe cases of bed sores or lifting damage

• Exposure

• Non alertness

Clinically unimportant secondary damage was inconsequential damage that did not affect the recovery from the recumbency. Conditions regarded as unimportant were:

• Mild bed sores, mild sacro-iliac strains, strained gastrocneumius muscle

• Mild sciatic nerve damage and tibial paresis

• Mild presentations of mastitis, pneumonia and diarrhoea

Chapter 5: The Importance of Secondary Damage in Downer Cows

Types of damage where the frequency was too low to be able to calculate meaningful statistical comparisons were combined into one of four categories:

1. Major disease: Severe manifestations of pneumonia, mastitis and diarrhoea; death from aspiration of rumen contents; severe bed sores and lifting damage; joint infections; and heart failure

2. Minor disease: Mild to moderate manifestations of pneumonia, mastitis and diarrhoea

3. Major structural: Moderate and severe manifestations of sciatic nerve damage; gastrocnemius rupture; obturator/adductor muscle damage; stifle rupture; and back fracture

4. Minor structural: Mild manifestations of sciatic nerve damage; gastrocnemius strain; sacro-iliac strain; and tibial paresis, both uni- and bilateral

Outcome was recorded at the seventh day following the initial recumbency and at its conclusion. Day 7 outcome was used as it was considered to be a ‘reasonable industry time period’ for nursing downer cows and was a more tangible measure than ‘eventual recovery’, which could involve protracted time periods.

Outcome had two categories: recovered or death

1. Recovered was defined as being able to consistently stand independently and walk around for at least the following two days

2. Death was either from: euthanasia, which was at the farmers’ discretion, unless I considered the animal was suffering welfare issues; or an acute medical condition where they were found dead

The progress of the cows was also assessed at day 7, which was either: ‘able to stand’; ‘walk if lifted’; ‘stand if lifted’; ‘still down’; ‘euthanased’; or ‘died’.

A successful outcome was defined as recovered by day 7. An unsuccessful outcome was defined as not recovered by day 7, either still being nursed or deceased.

A retrospective judgement on each cow was made as to whether the failure to recover was due to the primary condition, the secondary complications or a combination of both.

Chapter 5: The Importance of Secondary Damage in Downer Cows

5.2.1 Statistical analysis A case cow was defined as not recovered by day 7 and a control cow as recovered by day 7. Logistic regression and the odds ratio, 95% CI and Wald P value were used to measure the strength of association between risk factors and case/control status. If any cell in a 2 X 2 table was zero, 0.5 was added to each cell frequency before the calculation to report an adjusted odds ratio and 95% CI (Fleiss et al., 2003). A likelihood ratio test evaluated the significance of a factor with more than two levels. Statistical analysis of recovery between the different primary groups used calving paralysis as the reference group because this had the largest number of cows. The group of cows without any type of secondary damage was the reference group for analysing the statistical significance of individual types of secondary damage. The sensitivity, specificity, positive predictive value, negative predictive value and area under the receiver operating characteristic curve for the CK threshold were estimated with the –diagt- command of Stata. Stata 13.1 for Windows (StataCorp, College Station, TX) and WinPepi 11.48 (Abramson, 2011) software were used to conduct the analyses. Two- sided P values < 0.05 were regarded as statistically significant.

5.3 Results There were 218 cows from 96 farms that satisfied the study criteria. The breakdown of the primary cause of their recumbency and their fate are shown in Table 5.2.

Table 5.2. Primary cause of recumbency, day 7 and final recovery of 218 downer cows Primary cause of Cows Recovered by day 7 Recovered by final recumbency outcome n % n % n % Milk fever 37 17 12 32 15 41 Protein-energy 30 14 4 13 7 23 deficiency Calving paralysis 98 45 23 23 33 34 Back injury 41 19 12 29 12 29 Other 12 5 1 8 2 17 Total 218 100 52 24 69 32

The calving paralysis group had a day 7 recovery of 23%. When this was used as the reference group there was no significant difference in recovery by day 7 with any of the other groups, as shown in Table 5.3.

Chapter 5: The Importance of Secondary Damage in Downer Cows

Table 5.3. Results of univariable logistic regression analysis for still being recumbent (case) by day 7 for 218 downer cows by primary cause Primary cause Total Case Control Odds 95% CI P n=218 n=166 (76%) n=52 (24%) ratio LRTa 0.19 Calving paralysis 98 (45%) 75 (77%) 23 (23%) 1 [REF] Milk fever 37 (17%) 25 (68%) 12 (32%) 0.64 0.3-1.5 0.29 Protein-energy 30 (14%) 26 (87%) 4 (13%) 2.0 0.6-6.3 0.24 deficiency Back injury 41 (19%) 29 (71%) 12 (29%) 0.74 0.3-1.7 0.47 Other 12 (6%) 11(92%) 1 (8%) 3.4 0.4-27.5 0.26 aLikelihood ratio test, otherwise Wald P value.

When the logistic regression analysis was repeated for primary cause still being recumbent by day three, five and final recovery, the P values were 0.43, 0.44 and 0.41, respectively.

By day 7, 52 (24%) cows had recovered, 46 (21%) continued to be nursed and 120 (55%) were deceased. Their progress at day 7 and their final status is shown in Table 5.4.

Table 5.4. Day 7 progress of 218 downer cows Cow status Day 7 Final n % n % Recovered 52 24 69 32 Walk if lifted 12 6 0 - Stand if lifted 15 7 0 - Unable to stand 19 9 0 - Euthanased 104 48 131 60 Died 16 7 18 8 Total 218 100 218 100

Of the 16 cows that had died by day 7, nine had died from choking on aspirated rumen contents, two from acute mastitis, one from kidney failure, one from acute diarrhoea and three from unknown causes. Two other cows died after day 7, both from aspiration.

The daily recovery and loss versus time are shown in Figure 5.1, where each red square represents the cumulative percentage loss at that time period and blue diamonds represent the cumulative percentage recovery at that time period.

Chapter 5: The Importance of Secondary Damage in Downer Cows

Figure 5.1. Cumulative daily loss and recovery percentages for 218 downer cows

80 Cumulative daily loss and recovery % 70

60 Cumulative daily

50 recovery % (n=69)

Cumulative daily loss 40 % % (n=149)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Days recumbent

By the end of day 7, 52/218 (24%) cows had recovered, 46 (21%) cows were still being nursed and 120 (55%) cows had been euthanased or had died. There were 46 cows that had not recovered by day 7 that were still being nursed and of these, 17 (37%) cows eventually recovered.

By the end of day 14, 66/218 (30%) cows had recovered, 11 (5%) cows were still being nursed and 141 (65%) cows had been euthanased or had died. Of the 11 cows that had not recovered by day 14 that were still being nursed, three (27%) cows eventually recovered.

By the end of day 21, 68/218 (31%) cows had recovered, four (5%) cows were still being nursed and 146 (67%) cows had been euthanased or had died. Of the 4 cows that had not recovered by day 21 that were still being nursed, one (25%) cow eventually recovered.

Final recovery was 69/218 (32%). Of the 149 cows which did not survive, 131 were euthanased and 18 died.

Chapter 5: The Importance of Secondary Damage in Downer Cows

Of the 149 cows that eventually either died or were euthanased, a clinical judgment was made as to whether the cause of their demise was due to the primary condition by which they were afflicted, the secondary damage they suffered from or a combination of both: 23 (15%) cows were deemed to have not recovered solely from the primary cause, 107 (72%) cows solely from secondary damage and 19 (13%) cows from a combination of primary and secondary conditions.

The occurrence of secondary complications was very common with 183/218 (84%) cows affected by some type of secondary damage. Of these, 101 had more than one type of secondary damage with one cow having six different types. Only 35/218 (16%) cows had no observed secondary damage. It was judged that 173/218 (79%) cows suffered clinically important secondary damage. Five of these cows were left with permanent secondary damage that affected their gait even though they were able to stand and walk.

There were 25 different types of secondary damage recorded. After the minor groups were amalgamated there were 15 different types of secondary damage for analysis, including ‘any type’, ‘clinically important’ and the two grades of secondary femoral nerve damage.

These are listed in Table 5.5 with their occurrence, number of cases (number of cows not recovered by day 7), controls (number of cows recovered by day 7), odds ratio, Wald 95% confidence interval and Wald P value when compared to the reference group of cows without any secondary damage.

There were 35 cows without any recorded secondary damage, of which 20 (57%) had recovered by day 7 and 15 (43%) had not.

Most of the types of secondary damage that were considered to be clinically important were found to be statistically significant when compared to the group without any secondary damage. Radial and mild femoral nerve damage were found to be not statistically different. Other categories of damage that were found to be statistically significant, as shown in Table 5.5, were ‘any type’ of secondary damage, ‘clinically important’ damage and major and minor structural damage.

The group of cows with minor structural damage was found to be statistically different to the reference group. This group had 32 cows, eight of which had recovered by day 7 and 24 had not. However, 20 of these cows had other types of ‘statistically significant’ secondary

Chapter 5: The Importance of Secondary Damage in Downer Cows damage, only one of which had recovered by day 7. Examples of other types of ‘statistically significant’ damage that they suffered were brachial plexus paralysis and hip dislocation. This extra damage probably caused the demise of these cows, rather than the minor structural type. The other 12 cows in this group only had minor structural damage or had other types of damage that were not statistically significant. By day 7, seven (58%) of these cows had recovered and five (42%) had not. When this group of 12 cows was analysed separately, it was not statistically different to the reference group of ‘no secondary damage’ (OR 0.95; 95% CI 0.3-3.6; P = 0.94). Thus, these types of secondary damage were deemed not statistically significant.

Chapter 5: The Importance of Secondary Damage in Downer Cows

Table 5.5. Results of univariable logistic regression analysis assessing risk factors for still being recumbent (case) by day 7 for 218 downer cows

Type of secondary Total Case Control Odds 95% CI Wald P damage n=218 166 (76%) 52 (24%) Ratio n % n % n % No secondary damage 35 16 15 43 20 57 1[REF]

Any type of secondary 183 84 151 83 32 17 6.3 2.9-13.6 <0.0001 damage Clinically important 173 79 148 86 25 14 7.9 3.6-17.4 <0.0001 secondary damage Radial nerve 15 6.9 11 73 4 27 3.7 0.97-13.8 0.055

Brachial plexus 23 11 23 100 0 0 62.2a 3.5-1,105 0.005

Femoral – mild 35 16 20 57 15 43 1.8 0.7-4.6 0.23

Femoral - severe 13 6.0 13 100 0 0 35.7a 2.0-648 0.016

Muscle atrophy 21 10 21 100 0 0 56.9a 3.2-1,014 0.006

Hip dislocation 30 14 30 100 0 0 80.7a 4.6-1,425 0.003

Major structural 21 10 20 95 1 4.8 26.7 3.2-222 0.002

Minor structural –all cows 32 15 24 75 8 25 4.0 1.4-11.4 0.009

Minor structural without 12 5.5 5 42 7 48 0.95 0.3-3.6 0.94 other important damage Major disease 30 14 30 100 0 0 80.7a 4.6-1,425 0.003

Minor disease 3 1.4 2 67 1 33 2.7 0.2-32.2 0.44

Exposure 18 8.3 16 89 2 11 10.7 2.1-53.6 0.004 Non alert cow 31 14 31 100 0 0 83.3a 4.7-1,470 0.003

Compartment syndromebc 61 36 56 92 5 8.2 14.9 4.8-46.4 <0.0001 aAdjusted odds ratio, 0.5 added to each cell. bn = 168. cCompartment syndrome was diagnosed when CK concentrations were greater than the time adjusted multiple of the upper normal limit of Veterinary Clinical Pathology’s normal reference intervals (Table 5.1).

Chapter 5: The Importance of Secondary Damage in Downer Cows

There were 168 cows that had CK concentrations measured, of which 119 (71%) did not recover. By day 7, only 5/61 (8.2%) cows with CK concentrations above the critical level had recovered, which was significantly different to the 20/35 (57%) cows recovered by day 7 that had no secondary damage (OR 14.9; 95% CI 4.8-46.4; P < 0.0001), as shown in Table 5.5. The difference in recovery of the cows with CK concentrations above the critical threshold was also significantly different to the 33/107 (31%) cows with CK concentrations less than the critical level that had recovered by day 7 (OR 5.0; 95% CI 1.8-13.6; P = 0.002).

A further eight of the 107 cows with CK concentrations less than the critical level eventually recovered as did three of the 61 cows with CK concentrations above the critical level. The final outcome was 41/107 (38%) cows with CK concentrations less than critical had recovered, compared to 8/61 (13%) cows with CK concentrations greater than critical (OR 4.1; 95% CI 1.8-9.5; P = 0.001). The positive predictive value for non-recovery in this study’s cohort was 87% (95% CI 76-94) and the negative predictive value was 38% (95% CI 29-48). The sensitivity was 45% (95% CI 35-54) and the specificity 84% (95% CI 70-93). The area under the receiver operating characteristic curve was 0.64 (95% CI 0.57-0.71), which is considered low diagnostic accuracy (Gardner and Greiner, 2006).

Of the 61 cows that had CK concentrations above the ‘critical threshold’ only 10 had AST concentrations above its ‘critical threshold’. No cows had AST concentrations above the critical level without also having CK concentrations above the ‘critical threshold’. AST and CK concentrations expressed as a ratio of the critical value were correlated (r = 0.55 log data; P < 0.001; n = 168).

Data from this study were compared to these critical thresholds. Of the cows with CK concentrations greater than the time adjusted threshold, 8/61 (13%: 95% CI 5.8-24.2) eventually recovered.

5.4 Discussion There are a wide variety of conditions that can result in dairy cows becoming recumbent. Some of these, with appropriate treatment can be resolved quickly whereas others are so severe that they are unable to recover. Recumbent cows are susceptible to secondary damage from being down. The study found that once cows were recumbent for more than 24 hours their chance of recovery was more likely to be influenced by secondary damage

Chapter 5: The Importance of Secondary Damage in Downer Cows

than from the original primary condition. For cattle with severe primary conditions the primary damage was important but for the majority of cows in the study their fate was determined by the presence or absence of secondary damage. Primary damage was judged to be the sole cause of non-recovery in only 23 (15%) of the 149 cows that did not recover.

Secondary damage was very common with 183/218 (84%) cows suffering some type. There were 25 different types of secondary damage recorded and 101/218 (46%) cows had more than one type concurrently.

Secondary damage was very important with regards to recovery. The day 7 recovery of cows without any secondary damage was 57% compared to 17% for those with some type of secondary damage. Secondary damage was judged to be solely responsible for the non- recovery of 107 (72%) of the 149 cows that did not recover and jointly contributed with the primary cause in a further 19 (13%) cows. Cows with secondary damage that was deemed to be clinically important had decreased odds of recovery by day 7 of nearly eight times those cows without any type of secondary damage.

This finding highlights the importance of looking for secondary damage when examining recumbent cows and especially cows that have been down for more than one day. The primary condition needs to be known and treated appropriately but if this is the only aspect that is considered, then the subsequent management of the cows may be incorrect. For example, there were 37 downer cows in the study that originally became recumbent from post-parturient hypocalcaemia. Secondary damage caused their recumbency to continue after the original calcium deficiency was clinically judged to have been corrected. Secondary femoral nerve damage was the most common type of secondary damage in this group of cows, affecting 25 (68%) cows. Management for femoral nerve damage is quite different to that for hypocalcaemia such that if treatment plans for these cows had only been aimed at administering more calcium, the approach would have been totally inappropriate.

The cows in the study had initially become recumbent from a variety of conditions, which were a good representation of the common reasons for recumbency seen by veterinarians in the South Gippsland dairy region. The day 7 recovery was 24% and the final recovery for those nursed for a longer period was 32%. This compares to a recent Australian survey (Watson and Watson, 2012) that recorded approximately one third of cows down for more than 24 hours had recovered and to a New Zealand study that found a recovery of 39% of 74

Chapter 5: The Importance of Secondary Damage in Downer Cows

433 downer cows (Clark et al., 1987). Results from two English studies showed that 50% of the downer cows had recovered by four and seven days, respectively (Andrews, 1986, Chamberlain, 1987). Comparisons could not be made to explain the different results between the Australasian and English studies.

During a forum on downer cows (Huxley et al., 2010) experienced cattle veterinarians recommended that downer cows should be culled by the third to seventh day, with the median the fifth day, if they were still recumbent. This was qualified depending upon the level of care being provided. Another author suggested that the prognosis for recovery if still recumbent after ten days was poor (Andrews, 1992).

Findings from this study disagree with the literature, as it found that cows nursed in the second week recovered at similar levels, if not perhaps slightly better, than those in the first week. The low numbers of cows that continued to be nursed after the end of the second week made it difficult to draw robust conclusions from but they also suggest comparable levels to the first week, as 3/11 (27%) cows nursed after the end of the second week eventually recovered. The slope of the daily cumulative recovery percentage, as shown in Figure 5.1 did become shallower in the second week and flattened after then, but this was largely due to the reduced number of cows still being nursed. This is discussed more fully in Chapter 6.

Some types of secondary damage did not necessarily affect recovery. The importance of each type was evaluated statistically, by comparing the day 7 recovery to those without any type of secondary damage and clinically, where judgement was made as to whether the secondary damage contributed to the recumbency in its own right or delayed or prevented recovery from the original recumbency.

The statistical result of the importance matched the clinical judgment for most types of secondary damage. The less common secondary conditions, however, needed to be first combined into groups to allow statistical analysis to be meaningful as their frequencies were too low to be calculated individually. Radial nerve and mild femoral nerve damage were deemed to be clinically important but found to be not statistically significant when their day 7 outcome was analysed. The difference was due to the two measures assessing different things: Radial and mild femoral nerve damage contributed to the recumbency but did not affect recovery by day 7. 75

Chapter 5: The Importance of Secondary Damage in Downer Cows

Forelimb neuropathies were found to affect 38 (17%) cows, composed of 23 (11%) cows suffering brachial plexus paralysis and 15 (7%) cows suffering radial nerve paralysis. These neuropathies can be caused by persistent lateral recumbency, especially if lying on hard surfaces (Parkinson et al., 2010). All 38 cows had positive flexor-withdrawal reflexes when assessed in the recumbent position and it was only after they were lifted that a diagnosis of forelimb neuropathy was made. This highlights the importance of lifting recumbent cows as part of a musculo-skeletal examination.

It is important to differentiate between radial nerve and brachial plexus paralysis. This is because none of the cows with brachial plexus paralysis had recovered by day 7 whereas those radial nerve paralysis cows had similar recovery to those without any secondary damage.

The cows with brachial plexus paralysis tended to lie in lateral recumbency, which I postulated was due to their inability to use their forelimb to brace themselves in the upright position. Andrews (1992) suggested that cows that persistently lay in lateral recumbency may have brain damage or chronic metabolic conditions although many farmers consider that it indicates that the cow has lost the ‘will to live’. Findings from this study suggest that brachial plexus neuropathy is a likely cause of persistent lateral recumbency.

Secondary femoral nerve damage was found to be very common in this study with 48/218 (22%) cows afflicted by it, either mildly (35 cows) or severely (13 cows). This finding contradicts the literature, which suggests that femoral nerve damage is uncommon (Constable, 2004, Divers, 2004, Parkinson et al., 2010) or “occurs rarely” (Vaughan, 1964) in cattle. I suggest that this condition had been misdiagnosed in one study where cows with hind legs in the caudal position were considered to have “damage to the pubis or muscles and nerves in that area” (Andrews, 1992), as there was not any specific mention of the femoral nerve. The high occurrence of femoral nerve damage in this study suggests that veterinarians must include patellar reflex assessment in their neurological examination of recumbent cattle.

Compartment syndrome was a very common finding in the study affecting 61/168 (36%) cows tested for CK concentration. Compartment syndrome, which is a pressure induced ischaemic myonecrosis of the hamstring group of muscles is one cause of continued recumbency in downer cows (Cox et al., 1982, Van Metre, 2001). The time adjusted 76

Chapter 5: The Importance of Secondary Damage in Downer Cows

threshold levels set by Clark et al (1987) were based on a recovery of less than five per cent. In this study, 13% of the cows with levels above threshold recovered, suggesting the threshold may not apply to the current cohort of cows. The ability to predict a poor chance of recovery based on CK concentrations may well be a useful test for clinicians when examining recumbent cattle if no other reason for euthanasia has been found. Cows suffering from compartment syndrome will take longer to recover and have reduced chances of recovering so some farmers will elect euthanasia instead of treatment on the basis of a positive diagnosis of this condition from a blood test. Further refinement of the time-adjusted threshold levels could improve the ability to predict non-recovery and would be a benefit to advisors.

Secondary hip dislocation occurred in 30/218 (14%) cows. The hips were replaced in a number of cows under deep sedation but all relapsed shortly afterwards. Hip dislocation secondary to recumbency has a grave prognosis as the primary damage prevents any successful outcome so I recommend immediate euthanasia.

5.5 Conclusions The study found that except for recumbent cows with a severe primary condition, their fate once they had been down for more than one day was not largely determined by the original cause of their recumbency. The presence or absence of secondary damage was the major determinant of their outcome and was more important than the original cause of their recumbency in the majority of cows. Secondary damage was found to be very common and presented in many different ways. Management of downer cows must involve measures to prevent and/or treat secondary damage.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Chapter 6. High Quality Care Improves Outcome in Recumbent Cows

6.1 Introduction Downer cows can be defined as cows that are “down in sternal recumbency for more than 24 hours with no evidence of systemic illness” (Cox, 1981). Recumbent cows need to receive nursing care whilst recovering from their primary condition and are susceptible to secondary damage from being down. The management of recumbent cows is an important animal welfare issue for the dairy industry as they will suffer unnecessarily if not managed appropriately.

Guidelines for the nursing of recumbent cows are fairly general and are often based on knowledge gained through experience by veterinarians during their clinical work (Andrews, 1992, Huxley et al., 2010). Nursing recumbent cows is a complex process and involves a number of different components, some of which interact with each other. No documentation could be found in the literature of the quantitative effect of nursing quality.

Chapter 5 showed that once dairy cows had been recumbent for more than one day there was no significant difference in recovery between the five groups that caused the primary recumbency. The occurrence of clinically important secondary damage was found to be more important in determining fate than the initial cause of the recumbency, except in cows with a severe primary condition.

The aim of this chapter was to investigate if the quality of the nursing care influenced the occurrence of secondary damage and outcome in downer cows. If so, robust, evidence based guidelines for the optimum nursing care of recumbent cows could be developed.

6.2 Materials and Methods Field studies of recumbent cows on South Gippsland dairy farms were conducted during two three-month seasonal calving periods in the winter months of 2011 and 2012. Cows were included in the study if they were bright, alert and responsive; had been recumbent for more than one day; and an adequate history was available. Cows were initially attended by a veterinarian as soon as possible after the recumbency, ideally on the first day. Any cow that was not still recumbent on the following day was excluded from the data set. The cows were thoroughly examined and the farmers were closely questioned on the cows’ history to determine the cause of the recumbency and to detect any secondary damage. The

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

conditions under which the cows had been cared for prior to the first visit were recorded. Cows were visited as many times as possible during their recumbency, often once or twice weekly. At each visit the cows were examined to detect secondary damage, judge progress and re-assess nursing conditions.

The initial cause of the recumbency was allocated into one of five broad groups: post- parturient hypocalcaemia (milk fever); protein-energy deficiency (Parkinson et al., 2010); calving paralysis; back injury; and ‘other’. This was based on the history provided by the farmers and examinations conducted by the initial attending veterinarian.

Any damage that was diagnosed at the initial visit that was not consistent with the primary cause of the recumbency was regarded as initial secondary damage. Any damage diagnosed at subsequent visits that was not apparent at the initial visit was regarded as subsequent secondary damage.

All damage was assessed to determine if it was important from a clinical and statistical perspective (page 38). Clinically important secondary damage was regarded as secondary damage that contributed to the recumbency in its own right or delayed or prevented recovery from the original recumbency. Conditions considered to be clinically important were:

• Brachial plexus paralysis

• Radial nerve damage

• Femoral nerve damage

• Moderate and severe sciatic nerve damage

• Hip dislocation

• Compartment syndrome

• Muscle atrophy

• Severe presentations of diseases, such as mastitis, pneumonia and diarrhoea

• Severe cases of bed sores or lifting damage

• Major structural damage

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

• Exposure

• Non-alertness

Compartment syndrome is an ischaemic myo-necrosis, usually of the hamstring group of muscles (biceps femoralis, semitendinosus and semimembranosus) caused by compression of the muscles from being recumbent (Van Metre, 2001). It was diagnosed when creatinine phosphokinase (CK) concentrations were above a threshold level, based on a multiplication factor of the upper normal limit, shown to be associated with less than a 5% chance of recovery (Clark et al., 1987).

Exposure was defined as depressed cows with sub-normal body temperatures (less than 36.5 degrees centigrade) due to being subjected to very cold weather conditions.

Clinically unimportant secondary damage was damage that did not affect the recovery from the recumbency. Conditions regarded as unimportant were:

• Mild bed sores, mild sacro-iliac strains, strained gastrocneumius muscle

• Mild sciatic nerve damage and tibial paresis

• Mild presentations of mastitis, pneumonia and diarrhoea

Outcome was recorded at the seventh day following the initial recumbency and at its conclusion. It was decided that day 7 outcome was the main outcome as it was considered to be a ‘reasonable industry time period’ for nursing downer cows and was a more tangible measure than ‘eventual recovery’, which could involve protracted time periods.

Outcome had two categories: recovered or death

1. Recovered was defined as being able to consistently stand independently and walk around for at least the following two days

2. Death was either from: euthanasia, which was at the farmers’ discretion, unless I considered the animal was suffering welfare issue; or an acute medical condition where they were found dead

A successful outcome was defined as recovered by day 7. An unsuccessful outcome was defined as not recovered by day 7, either still being nursed or deceased.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Non-steroidal anti-inflammatory (NSAID) drug treatment use was recorded for the downer cows examined in the study but the specific type, timing, dose rate and whether it was administered by the farmer or veterinarian was not recorded.

Recumbent cows need to be adequately treated and cared for to maximise their chance of recovery. There are multiple components of nursing care including: location; bedding; shelter; feed and water; rolling; lifting; and hygiene. I defined what I considered to be the ideal level of management for southern Victorian conditions, based on the available information in the literature (Cox, 1982, Huxley, 2006, Huxley et al., 2010) and on my experience over thirty years of dairy cattle veterinary practice. This is shown in Table 6.1.

There were a large number of components of nursing care recorded and their implementation varied considerably between farms and often within farms. This made it difficult to analyse the influence of individual nursing components on outcome necessitating the development of a four-tiered grading system (nursing score) to summarize the conditions under which the cows were cared for, relative to the optimal nursing conditions, listed in Table 6.1. The nursing score reflected the effectiveness of the implementation of the proposed nursing requirements. It took into consideration both the degree of compliance for each nursing component and the relative period of time that the requirements were fully implemented, as shown in Table 6.2. The increasing scores reflect a decreasing compliance with the optimum standard.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.1. Optimum standard of nursing care for recumbent cows in southern Victorian dairying areas Component Description Treatment Appropriately treated for the primary cause of the recumbency Appropriately treated for any secondary conditions following the recumbency Location For recumbent cows: • Cared for in a small, sheltered area within a shed For cows that are unable to stand unassisted but can walk after being lifted: • kept away from slippery surfaces • isolated from other cattle • lifted once or twice daily • closely monitored Bedding Cared for on deep, soft bedding of suitable material: • 40 - 50 cm of hay or straw • 20 - 30 cm of sawdust, rice hulls or sand • or equivalent substrate Weather conditions Protected from adverse weather conditions, including excessive cold and heat Barriers For recumbent cows: • barriers to restrict cows crawling more than 3 - 4 metres • barriers to prevent cows crawling off the suitable bedding For cows that can stand after being lifted but unable to walk: • barriers to prevent walking when standing Rolling For cows that are unable to swap sides by themselves: • rolled off dependent leg several times daily Lifting Cow only lifted if: • ‘effective’, which is the ability for the cow to take some of its own weight after being lifted and is not hanging from the lifting clamp or within the frame • ‘supervised’ by the carer so the cow can be lowered when observed to be no longer standing effectively Hygiene Clean and dry conditions are provided Area is regularly cleaned to prevent build-up of manure, urine and moisture Level of care High levels of ‘tender love and care’ provided at all times Adequate levels of labour provided Feed and water Access to good quality feed at all times Adequate provision of suitable drinking water Udder care Milking is optional unless leaking milk Teat disinfection twice daily Moving between location Moved in a way to avoid inflicting further damage, such as by: • front-end loading bucket • ‘carry-all’

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.2. Criteria of the four nursing scores used in this study Nursing score Compliance with the optimum standard of caring One Excellent compliance Nursing requirements were implemented with more than 75% effectiveness or were fully implemented for more than 75% of the time Two Good compliance Nursing requirements were implemented with 50 - 75% effectiveness or were fully implemented for 50 - 75% of the time For example: • In paddocks when weather conditions were favourable, the paddocks were flat and the ground soft with some ‘give’ in it • nursing compliance was ‘poor’ for part of the time and ‘excellent’ for the remaining part so the overall compliance was averaged to be ‘good’ Three Poor compliance Nursing requirements were implemented with only 25 - 49% effectiveness or were fully implemented for only 25 - 49% of the time For example: • outside in cold and wet conditions, but not extremely so • in the paddock where the ground was cold and wet or hard • in sheds on dirt or gravel with only a token amount of soft bedding • cows crawled off suitable bedding Four Very poor compliance Nursing requirements were implemented with less than 25% effectiveness or were fully implemented for less than 25% of the time For example: • very wet, muddy and cold conditions • on very hard surfaces, such as concrete or gravel • allowed to crawl around unrestricted over more than 3 - 4 metres • found to be lying in heavily soiled areas for more than one day • obvious neglect and lack of care, such as lying in lateral recumbency for extended periods

A separate score was allocated for the ‘initial’, ‘subsequent’ and ‘overall’ nursing periods. The initial period was defined as the conditions the cows were nursed prior to the first visit. This was assessed on the basis of conditions observed at my first visit and on the history obtained from the farmers. The subsequent period was the period of time that I directly observed. The subsequent nursing score was allocated at the end of the nursing period to reflect an average of the observed conditions over the period as conditions could have changed during that time. The overall nursing score was a weighted average of the initial and subsequent nursing scores, reflecting the relative duration of time under each period. The nursing scores for the three nursing periods were allocated at the conclusion of each

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

period when all of the nursing factors were known but without taking into consideration the outcome of the cow.

Score 2 nursing was reasonably compliant with the desired level of optimal nursing care whereas Scores 3 and 4 were markedly different. For some analyses Scores 1 and 2 were combined to form a category described as ‘satisfactory’ nursing and Scores 3 and 4 were combined as ‘unsatisfactory’ nursing.

6.2.1 Statistical analysis A case cow was defined as not recovered by day 7 and a control cow as recovered by day 7. Logistic regression and the odds ratio (OR), 95% confidence interval (CI) and Wald P value were used to measure the strength of association between risk factors and case/control status. If any cell in a 2 X 2 table was zero, 0.5 was added to each cell frequency before the calculation to report an adjusted odds ratio and 95% CI (Fleiss et al., 2003). The Cochran- Armitage test for trend (Armitage, 1955, Cochran, 1954) was used to test for a linear component of trend between nursing scores and the proportion of cows with a given binary outcome. StatXact software was used to calculate the exact P value for the Cochran- Armitage test for trend. StatXact 10 (Cytel, Cambridge, MA) and WinPepi 11.48 (Abramson, 2011) software were used for the analyses. Two-sided P values < 0.05 were regarded as statistically significant.

6.3 Results When the overall nursing conditions were assessed for the 218 cows, it was judged that 73 (33%) cows had been nursed overall under Score 1 (excellent compliance) conditions, 78 (36%) cows under Score 2 (good compliance) conditions, 52 (24%) cows under Score 3 (poor compliance) conditions and 15 (7%) cows under Score 4 (very poor compliance) nursing conditions.

There was a very strong association between day 7 recovery and the nursing quality during the three nursing periods, as shown in Table 6.3.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.3. Day 7 recovery by nursing scores for the three nursing periods for 218 downer cows Nursing score for Initial period Subsequent period Overall period each nursing period Recovered by day 7 Recovered by day 7 Recovered by day 7 n % n % n % One 20/65 31 30/88 34 24/73 33 Two 13/51 25 17/58 29 24/78 31 Three 16/76 21 3/35 9 4/52 8 Four 3/26 12 0/5 0 0/15 0 Total 52/218 24 50/186 27 52/218 24 Cochran-Armitage P = 0.043 P = 0.003 P = 0.0001 test for trend

When the quality of the nursing during the three nursing periods was analysed against final outcome the association was also very strong, as shown in Table 6.4.

Table 6.4. Final recovery by nursing scores for the three nursing periods for 218 downer cows Nursing score for Initial period Subsequent period Overall period each nursing Eventually Eventually Eventually period recovered recovered recovered n % n % n % One 29/65 45 42/88 48 33/73 45 Two 16/51 31 22/58 38 32/78 41 Three 20/76 26 3/35 9 4/52 8 Four 4/26 15 0/5 0 0/15 0 Total 69/218 32 67/186 36 69/218 32 Cochran-Armitage P = 0.003 P < 0.0001 P < 0.0001 test for trend

The daily cumulative recovery percentage for the four nursing scores is shown graphically in Figure 6.1 and the daily cumulative death percentage for the four nursing scores is shown in Figure 6.2.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Figure 6.1. Daily cumulative recovery percentage by overall nursing score for 218 downer cows

40 Nursing score 1 (n=73) 35

30 Nursing score 2 (n=78)

Cumulative recovery % 25 Nursing score 3 (n=52) 20

15 Nursing score 4 (n=15)

0 0 5 10 15 20 25 30 Days recumbent

Figure 6.2. Daily cumulative death percentage by overall nursing score for 218 downer cows

120

100 %

death 80

60 Cumulative Nursing score 1 (n=73) 40 Nursing score 2 (n=78)

20 Nursing score 3 (n=52)

Nursing score 4 (n=15) 0 0 5 10 15 20 25 30 Days recumbent

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

The daily cumulative recovery percentage for the 65/151 (43%) cows nursed satisfactorily and the 4/65 (6%) cows nursed unsatisfactorily that recovered is in Figure 6.3

Figure 6.3. Daily cumulative recovery of 151 cows nursed satisfactorily compared to 67 cows nursed unsatisfactorily

% 40

30 Cows nursed 25 satisfactorily (n=151)

20 Cows nursed

Cumulative recovery unsatisfactorily (n=67) 15

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Days

At the initial visit, it was judged that 65 (30%) cows had been initially nursed under Score 1 conditions, 51 (23%) cows under Score 2, 76 (35%) cows under Score 3 and 26 (12%) cows under Score 4 conditions. Thus, 102/218 (47%) cows were being nursed under conditions regarded to be unsatisfactory when they were first attended.

After the initial visit, 186/218 (85%) cows continued to be nursed. Of the 32 cows that were not, 29 were euthanased at the first visit, one had died and two had recovered immediately after the first visit. Of the 186 cows that were nursed after the initial visit, 88 (47%) cows were nursed under Score 1 conditions, 58 (31%) cows under Score 2 conditions, 35 (19%) cows under Score 3 conditions and five (3%) cows under Score 4 conditions.

There were 46 cows that were nursed for longer than 7 days. Their final fate as related to their subsequent and overall nursing score is shown in Table 6.5.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.5. Final recovery of the 46 cows nursed for longer than seven days by nursing score for the subsequent and overall nursing periods Nursing score for Subsequent period Overall period each nursing period Eventually recovered Eventually recovered n % n % One 12/23 52 9/19 47 Two 5/14 36 8/16 50 Three 0/8 0 0/9 0 Four 0/1 0 0/2 0 Total 17/46 37 17/46 37 Cochran-Armitage P = 0.009 P = 0.023 test for trend

There was a strong association between final recovery and both subsequent and overall nursing score for those cows nursed for longer than seven days. No cows nursed for longer than five days under Score 3 or 4 conditions recovered compared to approximately half of the cows nursed under Score 1 and 2 conditions. There was no significant difference in recovery for the cows nursed for an extended period between those nursed under subsequent nursing Score 1 and 2 conditions (OR 2.0; 95% CI 0.5-7.7; P = 0.33).

6.3.1 Secondary damage Thirty-five of the 218 cows (16%) did not suffer any type of secondary damage. For the other 183 (84%) cows, some of the types of secondary damage were deemed to be unimportant in regard to prolonging or preventing recovery from the recumbency. Those types that were deemed to be clinically important were found in 173/218 (79%) of cows. The association between the nursing score for the three nursing periods and the occurrence of clinically important secondary damage within the corresponding nursing period is shown in Table 6.6.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.6. Relationship between the occurrence of clinically important secondary damage and nursing scores for the three nursing periods in 218 downer cows Nursing score for Initial clinically Subsequent clinically Overall clinically each nursing important secondary important secondary important secondary period damage during damage during damage during initial period subsequent period overall period n % n % n % One 23/65 35 48/88 55 50/73 68 Two 19/51 37 28/58 48 62/78 79 Three 51/76 67 24/35 69 46/52 88 Four 26/26 100 5/5 100 15/15 100 Total 119/218 55 105/186 56 173/218 79 Cochran-Armitage P < 0.0001 P = 0.081 P < 0.001 test for trend

For the 186 cows that continued to be nursed after the first visit, 116 (62%) subsequently suffered some type of secondary damage, which was clinically important in 105 (56%) cows. The test for trend for association between subsequent nursing score and subsequent clinically important secondary damage was not significant (P = 0.081), as shown in Table 6.6. However, if the cows subsequently nursed under Score 1 and 2 conditions were combined (satisfactory nursing) and compared with those subsequently nursed under Score 3 and 4 (unsatisfactory nursing) conditions, the association between the occurrence of subsequent clinically important secondary damage and nursing quality was significant, as shown in Table 6.7. Combining the four subsequent nursing scores into the two categories of satisfactory and unsatisfactory nursing can be justified as there was no statistical difference for the occurrence of subsequent clinically important secondary damage between subsequent nursing score 1 and 2 conditions (OR 1.3; 95% CI: 0.7-2.5; P = 0.46) or between subsequent nursing score 3 and 4 conditions (Adj OR 5.2; 95% CI 0.26-101; P = 0.28).

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

Table 6.7. Occurrence of subsequent clinically important secondary damage and the two combined nursing scores in 186 downer cows Combined subsequent Occurrence of subsequent Odds 95% CI P nursing scores clinically important ratio secondary damage n % Score one and two 76/146 52 1 [REF] (Satisfactory nursing) Score three and four 29/40 73 2.4 1.1-5.2 0.023 (Unsatisfactory nursing) Overall 105/186 56

Non-steroidal anti-inflammatory drugs were administered to 180/218 (83%) cows. By day 7, 44/180 (24%) of those cows treated with them had recovered compared to 8/38 (21%) of those that did not receive the drugs (OR 1.2; 95% CI 0.5-2.8; P = 0.66).

6.4 Discussion The data from this current study were used to investigate the influence the level of care had on outcome and on the occurrence of secondary damage in 218 downer dairy cows under field conditions in South Gippsland, Victoria.

No studies in the literature could be found that document the quantitative effect of nursing care on recovery of downer cows. This study found that the influence of nursing quality was very pronounced with a highly significant linear component of trend between increased level of care and an increased proportion of cows recovering by day 7 and finally recovering. The outcome for downer cows was directly affected by the quality of care they received whilst recumbent. Nearly one-third of the 151 cows nursed overall with either excellent or good compliance to optimum nursing conditions had recovered by day 7 whereas only four of the 52 (8%) nursed poorly and none of the 15 (0%) nursed very poorly had recovered. For those cows that continued to be nursed longer than seven days the difference was even more significant, as approximately half of the cows nursed under excellent or good conditions eventually recovered whereas none of those nursed poorly or very poorly recovered.

Cows that were recumbent from severe primary conditions, such as vertebral or pelvic fracture, did not have a chance of recovery even with high levels of nursing care. These

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

syndromes must be identified early in the course of the recumbency so the cows can be euthanased promptly to avoid unnecessary suffering. Those without such severe primary conditions had a chance of recovery if they were treated appropriately, cared for at a high level and given adequate time to heal. When satisfactory nursing (nursing scores 1 and 2) care was not provided only 4/67 (6%) cows had recovered by day 7 and no more recovered even if nursed longer than seven days. If satisfactory levels of nursing care (nursing scores 1 and 2) cannot be provided cows should be euthanased promptly as their chance of recovery are very low.

This pattern was similar whether initial, subsequent or overall nursing scores were analysed against day 7 and final outcome.

The data from the current study showed that nearly one half of the cows were nursed at an unsatisfactory level (nursing score 3 and 4) when they were first attended and nearly one third of these cows continued to be nursed unsatisfactorily over their entire nursing period. This indicates a general lack of awareness by dairy farmers in the study of the importance of high quality nursing care for recumbent cows. The combination of the high occurrence of sub-optimal nursing and the low recovery of cows cared for in this manner suggests that significantly better animal welfare outcomes could occur through improved education of farmers in the management of recumbent cows. Meaningful on-farm change in the care of recumbent cattle could be achieved, which would result in more successful outcomes and less unnecessary suffering.

The cause of the primary recumbency was categorised into either: post-parturient hypocalcaemia (milk fever); protein-energy deficiency; calving paralysis; back injury; or ‘other’. A finding from Chapter 5 of this study was that there was no difference in recovery between the various groups once the cows had been recumbent for more than one day. Secondary damage was shown to be very important in influencing downer cows’ chance of recovery and except in the circumstances of severe primary damage, was more important than the primary cause of the recumbency. The results from this chapter show a clear association between the level of nursing care of downer cows and the occurrence of clinically important secondary damage. The test for trend of this relationship for both initial and overall nursing was significant. It was not significant for subsequent nursing (P = 0.081) but when subsequent nursing scores 1 and 2 were combined into the category of

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

satisfactory nursing and compared to the combined subsequent nursing scores 3 and 4, the odds of clinically important secondary damage occurring was nearly two and a half times that of the unsatisfactorily nursed group and this difference was statistically significant (P = 0.023).

This study advocated that the optimum location for nursing recumbent cows in southern Victoria was in sheds on appropriate deep, soft bedding rather than in paddocks. Nursing recumbent cows in paddocks is often more convenient for farmers and can be satisfactory if weather conditions are suitable for cows to be nursed outside and if the ground is not too hard, too soft or too cold. However, the weather often changes in southern Victoria and conditions can quickly become unfavourable for nursing cows outside. This is particularly true during the high-risk calving period, which tends to be in the winter months. Nursing in sheds removes the risk of variable weather conditions and ensures they will be consistently cared for under compliant conditions.

This study clearly demonstrated that high quality nursing care was related to better recovery of downer cows. This was directly due to giving them a higher chance of recovery from the primary cause of their recumbency, and indirectly from a decreased chance of suffering clinically significant secondary damage with an improved chance of recovering from such damage, if it occurred.

The length of time that farmers nursed downer cows varied considerably, from two days to as long as 28 days. This depended on a range of factors including: the availability of labour and facilities; the economic value of the cow compared to the cost of nursing; and the desire and energy levels of the carers.

In previous studies about half of the downers rose within four (Andrews, 1983, Andrews, 1986) to seven days (Chamberlain, 1987). However, the current study found only a quarter (24%) of the cows had recovered by the seventh day. Day 7 recovery even for the cows nursed under Score 1 conditions still did not achieve the levels quoted in the literature, with only one third recovered by this time. It was difficult to compare this study’s findings with those in the literature because the recovery percentages were not supported with actual numbers and the nursing conditions were not detailed. Andrews (1983) commented that recovery was dependent on “adequate nursing”, but only listed the need for “sufficient

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

bedding, good body condition, good stockmanship and outside rather than inside locations” in the description of adequate nursing.

A review of recumbency in adult cattle (Huxley et al., 2010) showed that the median number of days to pass before veterinarians recommended cows should be culled was five, with a range of three to seven. This was qualified depending upon the level of care being provided. Andrews (1983) suggested that the prognosis for those still down after 10 days was poor. Whilst the figures in these two articles were derived from general opinions of experienced cattle veterinarians, rather than robust science, they were the only articles that could be found with any numerical values.

Findings from this study clearly show that the quality of nursing was a more important determinant of a downer cow’s prognosis than the recumbency time period. Only 4/67 (6%) cows nursed at an unsatisfactory level recovered compared to 65/151 (43%) cows nursed satisfactorily. The four cows nursed unsatisfactorily that recovered did so within the first five days, and none of the remaining 27 (0%) cows still being nursed under those conditions recovered after day 5, despite one being nursed for as long as 28 days. The recovery figures for the cows nursed unsatisfactorily support the recommendations in the literature. However, for the cows that were nursed satisfactorily, cows continued to recover, even after as long as 27 days. When recovery of the cows that were nursed under satisfactory conditions was analysed by the week it was found that 48/151 (32%) cows had recovered during the first week. Thirty five (23%) cows continued to be nursed after the first week and 17 (49%) of these cows eventually recovered. There were eight (5%) cows still being nursed after the end of the second week and three (38%) cows eventually recovered. One the three (33%) cows that were still being nursed into the fourth week eventually recovered. Whilst the numbers for the third and fourth weeks are too low to draw robust conclusions from, they still indicate a comparable recovery to the first week. This is in contrast to the literature (Andrews, 1983, Chamberlain, 1987, Huxley, 2006).

It is possible that the reason the chance of recovery improved in the second week, compared to the first week, for cows nursed satisfactorily was that the farmers that persisted with their recumbent cows were the ones that dedicated more time and effort into nursing. These farmers were rewarded for their efforts, unlike the farmers that provided unsatisfactory nursing care, as none of the 11 (0%) cows nursed at an

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

unsatisfactory standard beyond the first week recovered. This difference is clearly shown in Figure 6.3.

The findings in this study demonstrate that providing the level of nursing care is suitable and the welfare of the animal is considered, euthanasia of recumbent cows need not be based on a defined time period. The quality of the nursing, in fact, is one of the major factors to be considered when deciding whether to allow time for recumbent cows to recover. For cattle without damage of a grave nature and where the level of care is high, allowing extended periods of time to recover is appropriate. If however, downer cows cannot be nursed under suitable conditions and/or the stock people are unable or unwilling to provide the necessary level of care, they should be euthanased immediately as their chance of recovery is very poor. Euthanasia is essential if they are suffering or if they are afflicted with conditions with a grave prognosis, regardless of their level of care.

Cows were grazed in paddocks in South Gippsland and winter conditions were often wet and cold. Many farmers nursed their recumbent cows in paddocks for reasons of convenience or lack of facilities. A large number of these cows were affected by cold conditions and some even showed clinical signs of exposure. The ground temperature was measured as low as 10°C at times and the lower leg skin temperatures of cows sitting in paddocks, measured with a thermo-imaging thermometer (Thermo-hunter PT-2L/LD made by Optex Co. Ltd) were as low as 11°C. Cows measured on the same day in sheds on a deep litter of suitable bedding had lower limb temperatures of 35°C. Cows with weakness in their limbs sitting on cold ground with low skin temperatures would be expected to have poor tissue perfusion in the limbs (Worster et al., 2000). This suggests that the healing of damaged structures or their ability to stand could be compromised. This would be further amplified in the dependent leg in cows that were unable to swap sides unassisted and/or not rolled regularly by their attendants.

The use of non-steroidal anti-inflammatory drugs (NSAID) is indicated for many of the primary causes of recumbency and many of the secondary complications (Parkinson et al., 2010, Smith-Maxie, 1997) as well as helping to relieve pain. In this study the cows that had been treated with NSAID did not show better recovery than those cows that had not been treated with the drugs. However, this study was not designed nor powered to investigate the role of NSAID therapy for recumbent cows and thus, this finding does not imply that

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

NSAID should not be used in a treatment regime. It is included to contrast to the finding from this study that recovery for downer cows was significantly increased by improved nursing quality. Many veterinarians rely on NSAID therapy as their main treatment for recumbent cows and do not engage in the cows’ nursing care. This finding should shift the emphasis of downer cow management towards nursing care rather than a straight reliance on the use of NSAID.

6.4.1 Limitations of the study The methodology of this chapter could be criticised as the categorisation of nursing quality into four levels was subjective, was not verified by a second opinion and was at the conclusion of the nursing period when the cow’s fate had been decided. This could lead to ‘researcher bias’ when allocating the nursing scores. However, these limitations were taken into consideration when the study was designed and were largely unavoidable due to its nature.

Ideally, to be able to assess the influence of nursing quality on outcome, the standard of nursing would have been measured quantitatively. There is no information in the literature describing the relative importance of the various nursing components that were recorded in this study. This made it impossible to allocate an exact numerical value on the nursing quality of individual cows, particularly as different cows were nursed under different levels of compliance to the different nursing factors. The cows were nursed under a range of conditions and by different people, resulting in a wide variation in the quality of the overall nursing. Rather than trying to allocate an exact numerical value to the nursing quality, nursing scores were developed to allocate the standard into one of four quartiles: ‘excellent’; ‘good’; ‘poor’; or ‘very poor’. Excellent nursing was defined as ‘compliance to the proposed optimal nursing standard that was implemented with more than 75% effectiveness or fully implemented for more than 75% of the time’. Allocation by quartile was a means of describing the quality of nursing in as an objective way as was possible.

I was the only person involved with data collection and it was not possible for the other people overseeing the project to attend the cows. Whilst this could lead to bias, the advantage was consistency and repeatability of the score allocation across the full cohort of cows.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

The nursing conditions of the cows’ could not be specified in advance so as to nurse some cows in one way and others in different but controlled ways. The study was an observational field study conducted on commercial dairy farms where the conditions were largely determined by the farmers and often changed during the course of the recumbency. The entire nursing details were not known until the completion of the recumbency. To overcome this limitation, nursing scores were allocated on the basis of the criteria shown in Table 6.2 and without taking outcome into consideration.

Whilst it could be argued that other researchers replicating this study may have interpreted the allocation of nursing scores differently, I consider that as the difference in outcome between cows nursed ‘satisfactorily’ and ‘unsatisfactorily’ was so dramatic the findings would have been similar and thus, the conclusions are valid.

The study clearly highlights the influence of nursing quality on recovery and points to the need to conduct further research in this area to more fully document the effect of the individual nursing components.

6.5 Conclusions The study has shown a very strong relationship between nursing quality and both day 7 and final outcome. None of the cows nursed very poorly recovered whereas nearly one-half of those nursed under excellent conditions recovered. This is an important finding as it will help focus attention on the importance of providing high quality nursing care to recumbent cows, leading to better recovery and animal welfare on dairy farms.

Improved nursing care allows better chances of cows recovering from the primary cause of their recumbency, decreased chances of suffering clinically significant secondary damage and improved chances of recovery from such damage, if it occurs.

Evidence from this study showed that if recumbent cows are nursed well and due consideration is given to their welfare, it is reasonable to nurse them for extended periods of time with good chances of success. There is no reason to euthanase them after a predetermined time period, as has been suggested in the literature. Conversely, if they are nursed in a sub-optimal manner they will have a very poor chance of recovery and should be euthanased promptly.

Chapter 6: High Quality Care Improves Outcome in Recumbent Cows

The quality of nursing care in South Gippsland was found to be generally low with nearly half of the cows found to have been subjected to a sub-optimal level of nursing when they were first attended. Downer cow management is an important animal welfare consideration for the dairy industry and this finding indicates there is an urgent need for education programs on the care of recumbent cows.

It is clear from this study that downer cows must either be nursed at a high level of care or euthanased promptly.

Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows

Chapter 7. Management of Bilateral Femoral Nerve Injuries in Cows

7.1 Introduction The femoral nerve is considered in the literature to be not particularly vulnerable to damage, as it is well protected along its course (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Vaughan, 1964). Femoral nerve damage is described as occurring most commonly in calves following dystocia where hip-lock has occurred (Constable, 2004, Divers, 2004, Parkinson et al., 2010). It is mentioned that it can occur in recumbent cattle, perhaps as a result of struggling to rise, but that it is more likely to be seen in calves following dystocia (Divers, 2004, Parkinson et al., 2010).

The femoral nerve in cattle forms from the ventral branch of the fifth lumbar (L5) nerve, with contributions from the fourth (L4) and sixth lumbar (L6) nerves. It innervates the quadriceps femoris, which is a strong extensor of the stifle joint and flexor of the hip. The femoral nerve gives branches to the: psoas and iliacus muscles, which flex the hip and rotate the thigh; and the sartorius muscle, which flexes the hip and adducts the limb. The saphenous nerve, a branch of the femoral nerve, continues along the medial aspect of the thigh providing sensory function to the fascia and skin of the medial aspect of the leg to the level immediately distal to the tarsus (Getty, 1975).

The only two journal articles that could be found in the literature describing femoral nerve damage involved the experimental sectioning of the femoral nerve in calves (Paulsen et al., 1981, Vaughan, 1964). No information on femoral nerve damage in adult cattle could be found. Experimental sectioning of the femoral nerve unilaterally in two calves at the medial aspect of the upper thigh caused the leg to be constantly semi-flexed and unable to bear weight. The claw only lightly touched the ground and the stifle buckled when trying to walk. The patellar reflex was absent. Atrophy of the quadriceps muscle was marked after 30 days (Vaughan, 1964). The results were similar in the second study (Paulsen et al., 1981).

I have commonly diagnosed femoral neuropathies in cows over many years and consider they occur more frequently than the literature suggests. I have previously developed a grading system to describe the various clinical presentations and severities for femoral neuropathies and advocate that the individual presentations need to be managed differently to maximise recovery. This research project offered an opportunity to investigate

Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows

femoral neuropathies more thoroughly and to attempt to validate my hypotheses. The hypotheses being tested were: that femoral nerve damage can be graded by a four-tiered system reflecting severity; that each level of damage should be managed differently; and that recovery is influenced by both the grade of injury and compliance to the desired level of management specific to the grade.

7.2 Materials and Methods Field studies of recumbent dairy cows were conducted in South Gippsland during two three- month periods in the winter calving months of 2011 and 2012. Cows were included in the study if they were bright, alert and responsive; and there was adequate history for them to be assessed properly. Calves and yearlings were excluded as were any cows with prior episodes of recumbency in the previous 30 days.

Cows were initially attended by a veterinarian as soon as possible after becoming recumbent, ideally on the first day. The cows were thoroughly examined clinically to determine the cause of the recumbency and to detect any secondary damage. The conditions of care prior to the first visit were recorded. I revisited the cows as many times as possible during their recumbency, often once or twice weekly. The farmers were not charged for my visits. The cows were examined as close to the seventh day as was possible, if they were still receiving nursing care and/or as close to the time of euthanasia as possible, if applicable. Farmers were instructed to inform me of any changes in progress of their cows so that any cows that had deteriorated from the previous visit could be re-assessed promptly, in addition to the scheduled revisits. Cows were re-examined at each visit to detect secondary damage, judge progress and re-assess nursing conditions.

The initial cause of the recumbency was allocated into one of five broad groups: post- parturient hypocalcaemia (milk fever); protein-energy deficiency (Parkinson et al., 2010); calving paralysis; back injury; and ‘other’. This was based on the history provided by the farmer and clinical examination conducted by the initial attending veterinarian.

From the data collected during the research project, a subset of bilateral femoral nerve injuries was identified. This group of cows was defined as having bilateral femoral nerve injuries, as either: primary damage; or secondary damage, in the absence of other significant unresolved primary conditions. Cows were excluded if veterinary examination

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revealed that they also had clinical symptoms of conditions such as sciatic or obturator nerve damage, or back or pelvic fracture. Cows with secondary bilateral femoral nerve injuries were included only if their primary condition, such as milk fever, had been resolved.

These selection criteria were used to limit the data set to cows with uncomplicated bilateral femoral nerve damage, in order to analyse this condition independent of other conditions.

Bilateral femoral nerve injuries in the recumbent cows were diagnosed by bilaterally depressed or absent patellar reflexes and a caudal tendency of the hind legs (Figure 7.1) when they tried to stand. As it was a bilateral condition, they were able to swap sides. I had previously developed a four-tiered grading system, based on motor function and posture, as shown in Table 7.1, to describe the clinical presentation and severity of the femoral neuropathies. The increased value of the grade represents a greater level of clinical abnormality. This grading system was used to describe the femoral neuropathies in the study.

Figure 7.1. Caudal tendency of hindlimbs in a cow with femoral nerve damage

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Table 7.1. Description of the four grades of femoral neuropathy in recumbent cows Femoral grade Description One Able to stand and walk normally after being lifted Patellar reflexes depressed but may be normal Two Stand independently when lifted but fall after a few steps Patellar reflexes usually absent but may be only depressed Three Unable to stand when lifted Able to maintain hindlimbs in the normal sitting position Absent patellar reflexes Four Unable to stand when lifted Hind limbs always caudal (frog-leg) when sitting Absent patellar reflexes

For some analyses, the four grades were combined into two groups, being mild and severe. Mildly affected cows could stand and/or walk after being lifted (Grades 1 and 2) whereas severely affected ones could not (Grades 3 and 4).

Outcome had two categories: recovered or death

1. Recovered was defined as being able to consistently stand independently and walk around for at least the following two days

2. Death was either from: euthanasia, which was at the farmers’ discretion, unless I considered the animal was suffering welfare issues; or an acute medical condition where they were found dead

A successful outcome was defined as recovered by day 7, which was used as the main outcome, as it was considered to be a ‘reasonable industry time period’ for nursing recumbent cows and was a more tangible measure than ‘eventual recovery’, which could involve protracted time periods. An unsuccessful outcome was defined as not recovered by day 7, either deceased or still requiring nursing care. During the nursing period cows may have remained at their original grade of femoral damage or they may have deteriorated to a more severe level of femoral damage. If they had suffered further damage, the more severe grade was used when outcome was analysed, as it was considered that this grade had the most impact on outcome.

Based on clinical experience over many years, I advocate that the four grades of femoral neuropathies should be managed differently. My recommendations for the optimum management of cows for each femoral grade are shown in Table 7.2.

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Data from this study were used to assess the validity of these recommendations.

To allow analysis of the effectiveness of these management recommendations for the four grades, a method for judging the effectiveness of implementing the guidelines needed to be developed. As a result, a four-tiered scoring system (nursing score) was developed for the study. The nursing scores describe the compliance to the optimal conditions for the grade of damage that the cows were nursed under, noting that these conditions varied for the different grades of femoral neuropathy. The increasing score reflects a decreasing compliance with the optimum standard, as shown in Table 7.3.

If the nursing conditions changed during the nursing period the compliance score was an average of the different conditions. For example, a cow that was nursed poorly for a few days then had excellent nursing would be averaged to compliance 2 (good).

Recovery was compared to nursing compliance for each femoral grade. Cows that had more than one level of femoral nerve damage also had more than one nursing score. They were analysed two ways to account for this: nursing score for the most severe (‘worst’) grade; and nursing score for the initial femoral grade. An unsuccessful outcome from the initial grade for these cows was expanded to include deterioration to a more severe grade. This allowed the outcome of the initial femoral grade to be analysed against the nursing compliance for the initial grade irrespective of the outcome of the more severe grade.

A post mortem examination was performed on one clinical case to investigate the syndrome more thoroughly.

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Table 7.2. Optimum care for cows with femoral neuropathies Femoral grade Management requirements One Located in areas which provide solid footing Kept away from slippery surfaces Lifted once or twice daily to allow them to walk around Closely monitored Hard surfaces are avoided when recumbent Restricted from crawling when recumbent Two Confined to a small pen approximately 3 - 4 metres square in a shed on deep, soft bedding of suitable material: • 40 - 50 cm of hay or straw • 20 - 30 cm of sawdust, rice hulls or sand • Or equivalent substrate Barriers to restrict crawling and walking Lifted once or twice daily within the pen to allow standing but prevented from walking Three Confined to a small pen approximately 3 - 4 metres square in a shed on deep, soft bedding of suitable material, as for Grade 2 Barriers to restrict crawling Not lifted by hip clamps as unable to take any of their own weight (ineffective lifting) Four Immediate euthanasia as the prognosis is hopeless One to three: Appropriately and promptly treated with non-steroidal other requirements anti-inflammatory (NSAID) drugs Protected from adverse weather conditions including excessive cold and heat Provision of clean and dry conditions Area regularly cleaned to prevent build-up of manure, urine and moisture High levels of ‘tender love and care’ provided at all times Adequate levels of labour provided to enable the level of nursing required Monitored regularly to ensure cows do not lie laterally Access to good quality feed at all times Adequate provision of suitable drinking water Milking is optional Teat disinfection twice daily Moved between locations in a way to avoid inflicting further damage

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Table 7.3. Criteria of the four nursing scores used to describe compliance to optimum level of care for the relevant femoral grade Nursing score Compliance with the optimum standard of caring One Excellent compliance Nursing requirements were implemented with more than 75% effectiveness or were fully implemented for more than 75% of the time Two Good compliance Nursing requirements were implemented with 50 - 75% effectiveness or were fully implemented for 50 - 75% of the time For example: • If cared for in paddocks the weather conditions were favourable, the paddocks were flat and the ground soft with some ‘give’ in it • If cared for in sheds, only minimal amounts or quality of bedding used • Barriers not used but cow not crawling around Three Poor compliance Nursing requirements were implemented with only 25 - 49% effectiveness or were fully implemented for only 25 - 49% of the time For example: • For Grade 1 femoral neuropathy: o Not isolated from other cows o Access to slippery surfaces • For all grades when recumbent: o Outside in cold and wet conditions, but not extremely so o In the paddock where the ground was cold and wet or hard o In sheds on dirt or gravel with only a token amount of soft bedding o Cows crawled off suitable bedding o Cows not prevented from crawling more than 3 - 4 metres o Not supervised closely Four Very poor compliance Nursing requirements were implemented with less than 25% effectiveness or were fully implemented for less than 25% of the time For example: • Very wet, muddy and cold conditions • On very hard surfaces, such as concrete or gravel • Allowed to crawl around unrestricted over distances of more than 3 - 4 metres • Found to be lying in heavily soiled areas for more than one day • Obvious neglect and lack of care, such as lying in lateral recumbency for extended periods

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7.2.2 Statistical analysis A case cow was defined as not recovered by day 7 and a control cow as recovered by day 7. Logistic regression and the odds ratio (OR), 95% confidence interval (CI) and Wald P value were used to measure the strength of association between risk factors and case/control status. If any cell in a 2 X 2 table was zero, 0.5 was added to each cell frequency before the calculation to report an adjusted odds ratio and 95% CI (Fleiss et al., 2003). The Cochran- Armitage test for trend (Armitage, 1955, Cochran, 1954) was used to test for a component of linear trend between the relevant score or femoral grade and the proportion of cows with a given binary outcome. StatXact software was used to calculate the exact P value for the Cochran-Armitage test for a linear component of trend. StatXact 10 (Cytel, Cambridge, MA) and WinPepi 11.48 (Abramson, 2011) software were used for the analyses. Two-sided P values < 0.05 were regarded as statistically significant.

7.3 Results There were 218 cows in the original study of recumbent cows (Chapter 5). Femoral nerve damage to one or both femoral nerves was recorded in 87 (40%) cows. Bilateral femoral nerve damage was recorded in 65 (30%) cows but 15 of these cows had other unresolved primary conditions, such as protein-energy deficiency or other neuropathies. There were 50/218 (23%) cows that satisfied the selection criteria of primary bilateral femoral neuropathy or secondary bilateral femoral neuropathy after the primary issue had been resolved.

Primary bilateral femoral neuropathy occurred in 25 cows, of which 24 had an injured back and the remaining cow had calving paralysis. Based on clinical evaluation, the primary damage was restricted to only the femoral nerves in these 25 cows, including the cow with calving paralysis. For the cows with secondary femoral nerve damage, the primary condition that caused the original recumbency was post-parturient hypocalcaemia (milk fever). In the original study of 218 cows there were 37 milk fever cows still recumbent on the day following the initial recumbency. Veterinary clinical examination determined that the original calcium deficiency had been corrected in all 37 cows and that 25 (68%) cows were still recumbent due to a secondary bilateral femoral neuropathy.

Of the cows in this study of femoral neuropathy, further damage to the femoral nerves occurred in 10/50 (20%) cows with nine cows having two grades of severity and one cow 106

Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows suffering three grades. Seven cows that originally presented with a Grade 1 femoral nerve injury deteriorated to a more severe grade, one of which deteriorated to a Grade 2, then to a Grade 3 femoral neuropathy. Three cows that originally presented as a Grade 2 femoral neuropathy deteriorated to a more severe grade.

By day 7, 21/50 (42%) cows had recovered and another four eventually did, giving a final recovery of 25/50 (50%). The severity of the femoral grade influenced the recovery, as shown in Table 7.4. For the ten cows with more than one grade of femoral damage the most severe grade was used in this analysis.

Table 7.4. Day 7 and final recovery of 50 cows with bilateral femoral nerve damage Most severe Day 7 recovery Final recovery femoral grade n n % n % One 19 11 58 13 68 Two 16 10 63 10 63 Three 13 0 0 2 15 Four 2 0 0 0 0 Total 50 21 42 25 50 Cochran-Armitage P = 0.001 P = 0.002 test for trend

When cows with Grade 1 and 2 femoral neuropathies were combined (mild femoral nerve damage) and compared to cows with Grade 3 and 4 femoral neuropathies (severe femoral nerve damage), 21/35 (60%) cows with the mild grades had recovered by day 7 compared to 0/15 (0%) cows with the severe grades (Adj OR 46.0; 95% CI 2.5–830; P = 0.010). Final recovery was 23/35 (66%) cows with the mild femoral grades compared to 2/15 (13%) cows with the severe femoral grades (OR 12.5; 95% CI 2.4–64.5; P = 0.003).

There was no statistical difference between the 11/19 (58%) femoral Grade 1 cows and 10/16 (63%) Grade 2 cows that had recovered by day 7 (OR 0.8; 95% CI 0.2–3.2; P = 0.78). There was no statistical difference between the 2/13 (15%) Grade 3 cows and the 0/2 (0%) Grade 4 femoral nerve cows that eventually recovered (Adj. OR 1.1; 95% CI 0.04–30.4; P = 0.96).

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Table 7.5, Table 7.6 and Table 7.7 show the length of time the cows with a ‘worst’ Grade 1, 2 and 3 femoral neuropathy, respectively, took to either: recover; or be destroyed; or die; following their recumbency.

Table 7.5. Number of days to outcome for ‘worst’ Grade 1 femoral nerve injury in 19 cows Outcome Number of days to outcome Total 1 2 3 4 5 6 7 8 9 10 11 12 13-15 16 17 18 cows Recovered 1 1 5 1 1 2 1 1 13 Euthanased 2 1 1 1 1 6 Died 0 Total 1 0 3 6 2 1 2 1 0 0 0 1 0 1 0 1 19

Eleven of the 13 cows with a Grade 1 femoral neuropathy that recovered did so within the first week with five cows recovering on day 4, but one cow took 12 days and another cow took 18 days to recover. One cow had not recovered after 16 days of management when she was destroyed from secondary complications after becoming cast laterally and suffering brachial plexus paralysis.

Table 7.6. Number of days to outcome for ‘worst’ Grade 2 femoral injury in 16 cows Outcome Number of days to outcome Total 1 2 3 4 5 6 7 8 9 10 11 12 cows Recovered 1 3 2 2 2 10 Euthanased 1 2 1 4 Died 1 1 2 Total 1 4 2 1 3 2 2 0 0 0 0 1 16

The ten cows with a Grade 2 femoral neuropathy that recovered did so within seven days but one cow did not recover even after 12 days of nursing.

Table 7.7. Number of days to outcome for ‘worst’ Grade 3 femoral injury in 13 cows Outcome Number of days to outcome Total 1 2 3 4 5 6 7 8 9 10 11 - 16 17 cows Recovered 1 1 2 Euthanased 1 1 1 1 1 1 2 2 10 Died 1 1 Total 0 2 1 1 1 1 1 3 0 1 0 2 13

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The two cows with a Grade 3 femoral neuropathy that recovered took an extended period of time to do so, being eight and ten days. Two cows with a Grade 3 femoral neuropathy did not recover even after 17 days of nursing.

The two cows with a Grade 4 neuropathy were destroyed after five and seven days of nursing.

The final recovery by compliance to the management requirements for each femoral grade in 50 cows, analysed by the ‘worst’ grade of femoral nerve damage is shown in Table 7.8.

Table 7.8. Outcome of ‘worst’ femoral grade by nursing score for 50 cows Nursing Final recovery by ‘worst’ grade Cochran- Score Armitage Grade 1 Grade 2 Grade 3 Grade 4 Total test for trend n % n % n % n % n % Excellent 11/14 79 8/11 73 2/8 25 0/2 0 21/35 60 0.004 Good 1/1 100 2/4 50 0/2 0 0/0 - 3/7 43 0.29 Poor 1/3 33 0/1 0 0/1 0 0/0 - 1/5 20 0.80 Very poor 0/1 0 0/0 - 0/2 0 0/0 - 0/3 0 N/A1 Total 13/19 68 10/16 63 2/13 15 0/2 0 25/50 50 0.002 Cochran- Armitage test 1 for trend 0.058 0.22 0.45 N/A 0.017

1Not applicable: unable to calculate due to all zero values in the columns or rows.

Of the 35 cows that had an excellent standard of care, 14 (40%) cows did not recover, as shown in Table 7.8. Six of these 14 cows (43%) died or were destroyed from secondary complications, such as infection, hip dislocation or brachial nerve paralysis.

The outcome of the initial femoral grade by nursing compliance is shown in Table 7.9, where non-recovery was either death or deterioration to a more severe femoral grade.

Of the seven cows with an initial Grade 1 femoral neuropathy that deteriorated to a more severe grade, six cows had been nursed with poor compliance to the care recommendations for Grade 1 femoral neuropathy and the other cow had been nursed with good compliance. Two of the four cows with an initial Grade 2 femoral neuropathy that deteriorated to a more severe grade had been nursed with very poor compliance to the proposed optimum conditions. The other two cows had deteriorated despite being nursed with excellent compliance to the recommendations for a Grade 2 femoral neuropathy.

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Table 7.9. Outcome of initial femoral grade by nursing score for 50 cows Nursing Final recovery from initial femoral grade1 Cochran- Score Armitage Grade 1 Grade 2 Grade 3 Grade 4 Total test for n % n % n % n % n % trend Excellent 11/14 79 7/10 70 2/4 50 0/0 20/28 71 0.39 Good 1/2 50 2/4 50 0/1 0 0/0 3/7 43 0.66 Poor 1/9 11 0/1 0 0/1 0 0/0 1/11 9 > 0.99 Very poor 0/1 0 0/2 0 0/1 0 0/0 0/4 0 N/A2 Total 13/26 50 9/17 53 2/7 29 0/0 24/50 48 0.56 Cochran- Armitage test 2 for trend 0.0015 0.061 0.38 N/A 0.0001 1Non-recovery is death or deteriorated to more severe grade. 2Not applicable: unable to calculate due to all zero values in the columns or rows.

When the cows with an initial Grade 2 femoral neuropathy nursed with excellent compliance were compared to those cows nursed with good, poor and very poor compliance, 7/10 (70%) recovered compared to 2/7 (29%) (OR 5.8; 95% CI 0.7-48.9; P = 0.10).

The cause of death for the 25 cows with a femoral neuropathy that were euthanased or died is shown in Table 7.10. Of the 12 cows that were euthanased from their femoral neuropathy, nine were complicated by suffering more than one grade of femoral nerve damage. The fatal diseases that occurred were two cases of aspiration pneumonia, one case of toxic mastitis and one case of per-acute Salmonellosis. One cow suffered chronic carpal joint infections from crawling on concrete and one cow suffered severe infection of the pelvic region from damage after being lifted with hip clamps.

Table 7.10. Cause of death for the 25 cows that did not recover Cause of death n % Primary or secondary femoral damage 12 48 Secondary disease/infection 6 24 Secondary brachial/radial paralysis 5 20 Secondary dislocated hip 1 4 Unknown 1 4 Total 25 100

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A post mortem examination was performed on one of the cows with a Grade 3 bilateral femoral neuropathy secondary to hypocalcaemia, after the cow had died from per-acute mastitis. The significant gross post mortem findings were epineural haemorrhages around the L4 and L5 nerve roots bilaterally. Unfortunately, the photographs taken of the gross lesions were not of a high enough quality to publish. Histological sections taken from affected femoral nerve roots did not show abnormalities in the nerve trunks, but in sections of the L4 nerve roots much of the adipose tissue adjacent to the nerves was necrotic, with lysis of nuclei and oedema, and there was extensive haemorrhage between the cells. The L5 femoral nerve root had similar findings, which are shown in Figure 7.2.

Figure 7.2. H&E stained section (bar equals 0.5 mm) of L5 femoral nerve root showing complete lysis and loss of cell nuclei in adipose tissue (right of image)and extensive haemorrhage between cells but the nerve trunk appears unaffected

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7.4 Discussion Findings from Chapter 5 revealed that the occurrence of femoral nerve damage in dairy cattle was common, as both a primary back injury, and as a secondary complication to other causes of recumbency, affecting 87/218 (40%) of cows. This is in contrast to the literature (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Vaughan, 1964) that states that femoral nerve damage is uncommon and that the most likely presentation is in calves subjected to hip-lock during a difficult birth process. Parkinson (2010) and Divers (2004) note that femoral nerve damage may occur when recumbent cattle struggle to rise by over- stretching the lumbar roots of the femoral nerve but still suggest that it is more commonly seen in calves following dystocia. Data from this study suggests that bilateral femoral nerve damage occurs commonly, both as a primary injury, and as secondary damage, presumably when recumbent cattle struggle to rise. Trauma to cows’ backs from mounting injuries or from falling could affect any of the musculo-skeletal structures of the lumbar and pelvic areas, including the femoral nerves but no mention of this could be found in the literature. When recumbent cattle are struggling to rise their hindlimbs have a tendency to slip behind them, which causes hyper-extension of the lumbar area. This could cause over-stretching of the femoral nerve roots at L4 and 5 and be the mechanism for secondary femoral nerve damage. Findings from the post mortem examination were consistent with this theory as there was extensive epineural haemorrhages around the L4 and L5 nerve roots bilaterally. This cow had been observed to crawl some 30 metres after being treated for hypocalcaemia. The lack of damage to the axons of the femoral nerve is consistent with neurapraxia, (a loss in nerve function without apparent structural change) rather than axonotmesis or neurotmesis (where structural changes to the nerve are evident on histopathological evaluation) (Platt and Garosi, 2012). Whilst it may be inappropriate to draw conclusions from only one cow, the observed changes suggest that the vascular supply to the nerve is more susceptible to a crush/stretch injury than the nerve itself. This is an area that requires further investigation.

In the extended study of 218 downer cows (Chapter 5) from which the 50 cows in this study were derived, secondary femoral nerve damage was found to have occurred in 25/37 (68%) cows originally recumbent from post-parturient hypocalcaemia (milk fever) that failed to rise after treatment. If cows with hypocalcaemia are not treated promptly or vigorously

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enough and remain recumbent they are at risk of crawling, which could cause femoral nerve damage and perpetuate the recumbency. It is important that cows with secondary femoral nerve damage are recognized as having this condition and not mistaken as on-going metabolic cases, as the management of these two syndromes are quite different.

Cows with bilateral femoral nerve damage presented with recumbency, bilaterally depressed or absent patellar reflexes, a caudal tendency in the positioning of the hind legs when they tried to stand (Figure 7.1) and the ability to swap sides. Their presentation varied according to the severity of the neuropathy from: being able to walk after being lifted; to recumbent and unable to retract their hind limbs under themselves in the normal sitting position. It is important for veterinarians to perform patellar reflex tests and look for a caudal hind limb tendency when performing musculo-skeletal examinations on recumbent cattle to be able to diagnose this syndrome. I postulate that failure by many veterinarians to include these tests in a standard musculo-skeletal examination may partially explain why it is under-diagnosed.

I proposed a four-tiered grading system for femoral neuropathies in this study to describe the different ways that femoral neuropathies present and to predict prognosis. Each grade described a distinctly different presentation of the condition and is logical, providing equipment is available to lift the cow as part of the examination. The potential of the grading system to predict prognosis for cows with femoral nerve damage was validated as there was a strong linear trend (P = 0.002) between decreased recovery of cows with increased grade of femoral damage. Of the 50 cows, 13/19 (68%) cows with a Grade 1 femoral neuropathy recovered compared to 10/16 (63%) cows with a Grade 2, 2/13 (15%) cows with a Grade 3 and 0/2 (0%) cows with a Grade 4 femoral neuropathy. Increased femoral grades reflect increased dysfunction of the femoral nerve roots, which would be expected to coincide with poorer probabilities of recovery.

The data for the Grade 3 femoral neuropathies suggest that this grade has a guarded prognosis with an extended recovery time, because only two of the 13 cows recovered and both these animals took longer than seven days to recover (Table 7.7). However, six cows with a Grade 3 femoral neuropathy were destroyed within less than a week of the onset of this grade so it is unknown how many may have recovered if given more time. If these animals had been given more time and if more of them had recovered, the conclusion may

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Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows have been that Grade 3 femoral neuropathy cases have a reasonable prognosis but only with an extended recovery time and under excellent nursing care. Neither of the two cows with a Grade 4 femoral neuropathy recovered, which fits my personal experience over many years. Cows afflicted with this level of femoral neuropathy have their hindlimbs constantly extended caudally, which hyper-extends the lumbar region. This abnormal posture would be expected to prevent healing of the original injury and cause further damage to the lumbar roots of the femoral nerve. I recommend immediate euthanasia for animals with a Grade 4 femoral neuropathy.

The second part of the research was to determine if the way cows with femoral neuropathies were managed influenced their chance of recovery and if so, to critically assess my suggested guidelines for management for each grade of femoral neuropathy.

Optimum management of each of the different femoral grades was proposed as part of this study. Cows with a Grade 1 femoral neuropathy were able to walk after being lifted so needed to be managed in areas with solid footing where they could walk around in isolation from other cattle. They must be protected from the risk of falling to reduce the chance of further damage occurring. Cows with a Grade 2 femoral neuropathy could stand after being lifted but fell readily when they tried to walk. They had to be lifted to the standing position but prevented from walking after being lifted, and from crawling when recumbent. Cows with a Grade 3 femoral neuropathy were unable to stand when lifted so lifting in a hip clamp was ineffective and was contra-indicated. They needed to be confined on soft, deep bedding, prevented from crawling and given time to heal before trying to lift again. Cows with a Grade 4 femoral neuropathy needed to be managed as for cows with a Grade 3 neuropathy if treatment was to be attempted but as the prognosis was grave immediate euthanasia was recommended. Cows with any grade of femoral neuropathy are susceptible to further damage to their femoral nerve roots if they fall or crawl, due to hyper-extension of the lumbar spine. Management procedures must be therefore instigated to reduce the chance of this occurring.

The guidelines for managing the different grades are shown in Table 7.2.

If these guidelines were sound there would be a strong linear trend of increased recovery with increased compliance to the guidelines for each femoral grade. This was shown when the four ‘worst’ grades were combined and outcome was analysed by compliance to the 114

Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows suggested nursing standards as 21/35 (60%) cows nursed with excellent compliance recovered compared to 3/7 (43%) cows nursed with good compliance and 1/8 (13%) cows nursed with poor or very poor compliance (test for trend P = 0.017), as shown in Table 7.8.

If the proposed management for cows with a Grade 1 femoral neuropathy, as shown in Table 7.2, were robust there would be a strong linear trend of increased recovery with increased compliance to the guidelines. When this relationship was analysed using the 19 cows with ‘worst’ Grade 1 femoral neuropathy, 11/14 (79%) cows nursed with excellent compliance recovered compared to 1/1 (100%), 1/3 (33%) and 0/1 (0%) cows nursed with good, poor and very poor compliance, respectively. However, this trend was not statistically significant (P = 0.058), as shown in Table 7.8, perhaps due to the limited number of cows.

When this relationship was analysed using cows with an initial Grade 1 femoral neuropathy there were 26 cows rather than 19 cows, as seven cows later deteriorated to a more severe grade. The definition of non-recovery from initial grade was expanded to include deterioration to a more severe grade so as to be able to analyse the effect of the specific nursing recommended for cows with a Grade 1 femoral neuropathy. Six of the seven cows that deteriorated to a more severe grade had been nursed poorly or very poorly and the other cow had been nursed with good compliance. When the recovery of the 26 cows with an initial Grade 1 femoral neuropathy was analysed against nursing compliance using the enlarged definition of non-recovery the test for trend was statistically significant (P = 0.0015), as shown in Table 7.9. This validated the proposed guidelines for the nursing of cows with a Grade 1 femoral neuropathy.

Once the seven cows had deteriorated to a more severe grade, the nursing requirements for their subsequent femoral grade(s) changed to the recommendations applicable to their subsequent femoral grade(s). The final fate, either recovered or death, of the seven cows with an initial Grade 1 femoral neuropathy that had deteriorated to a more severe grade was also influenced by their subsequent grade(s) and the nursing compliance for that grade(s). This made it difficult to draw conclusions on the influence the proposed guidelines for nursing cows with a Grade 1 femoral neuropathy had on the outcome without expanding the definition of non-recovery to include ‘deterioration to a more severe grade’.

When the guidelines for managing cows with a Grade 2 femoral neuropathy were analysed using recovery of the cows with a Grade 2 neuropathy against compliance to the proposed 115

Chapter 7: Management of Bilateral Femoral Nerve Injuries in Cows management there was a trend for increased recovery with increased compliance but it was not statistically significant. This was the case when it was analysed by ‘worst’ femoral grade (P = 0.22) and by initial femoral grade (P = 0.061). When the cows with an initial Grade 2 femoral neuropathy that were nursed with excellent compliance were compared to the other cows with an initial Grade 2 femoral neuropathy 7/10 (70%) recovered compared to 2/7 (29%). This was not significant statistically (P = 0.10). However, it was possible that the lack of statistical significance was due to the small number of cows in the sample as it has been my observation over many years that cows with a Grade 2 femoral neuropathy need to be managed by allowing them to stand but not walk to maximise their chance of recovery. Many farmers tend to continually lift these cows to encourage them to walk but if they are not within a confined area they usually fall readily causing further damage to the lumbar roots of the femoral nerves.

Cows with a Grade 3 femoral neuropathy carry a guarded prognosis, as only 2/13 (15%) cows recovered overall. The two cows that did recover were both nursed with excellent compliance to the proposed guidelines although another six cows nursed with excellent compliance did not recover, including one cow nursed for 16 days. None of the five cows with a Grade 3 femoral neuropathy that were nursed at a compliance level less than excellent recovered. Treatment of this level of damage to the femoral nerves should only be recommended it the stock carers are prepared to care for the cow for an extended period of time and at an excellent level. Alternatively, this poor result may suggest that there could be better ways to manage cows with a Grade 3 femoral neuropathy.

The two cows with a Grade 4 femoral neuropathy did not recover despite excellent nursing. Whilst it could be dangerous to draw conclusions from this small sample size, it is my experience over many years that this group of cows do not recover due to the continued hyper-extension of their lumbar spine. I recommend prompt euthanasia when the level of damage to the femoral nerves is this severe.

Cows with any grade of femoral nerve damage are at risk of further damage to their femoral nerves, which presents as deteriorating to a more severe grade of the syndrome. If this occurs, it must be recognised so their management can be modified to be compliant with the new grade. Further damage usually resulted from crawling or falling when they were managed inappropriately for the original grade.

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The nursing guidelines were designed to maximise the chance of cows recovering from their grade of femoral neuropathy and minimize the chance of suffering further femoral damage. They were also designed to reduce the chance of other clinically important secondary conditions occurring. Chapter 5 showed that for the majority of cows recumbent for more than one day secondary damage was more important in determining their fate than the original cause of the recumbency. The occurrence of secondary damage was directly related to the quality of the nursing care provided to downer cows, as shown in Chapter 6, and there was a strong association between improved recovery and better nursing. Non-femoral nerve secondary damage caused the death of 13/25 (42%) of the cows that did not recover. Some of these occurrences were related to sub-optimal nursing care but others occurred despite the provision of excellent nursing. This complicated the assessment of the validity of the nursing guidelines, particularly when small numbers were involved, as their death from secondary damage made it difficult to judge if the proposed guidelines for their femoral neuropathy were appropriate.

Further work is needed to test the hypothesis that struggling to rise can cause over- stretching of the femoral nerve roots and cause femoral nerve damage. Post mortem examination and pathology may lead to a better understanding of the syndrome.

The limitations to the findings from Chapter 6 in regard to allocation of nursing compliance also apply to this chapter.

7.5 Conclusion The study showed that bilateral femoral nerve dysfunction was common in recumbent cows, both arising from a primary back injury and as a secondary complication of recumbency. It is essential to include patellar reflex testing in musculo-skeletal examinations of recumbent cattle to facilitate diagnosis of this condition. The proposed four-tiered grading system to describe the severity of the neuropathy was validated by the findings of the study. It can be used to describe the syndrome, to predict prognosis and to advise on management. The optimum conditions for caring for each of the different grades of femoral neuropathy were proposed as part of this study. There was a strong linear trend towards increased recovery with increased compliance of the proposed nursing guidelines across the femoral grades overall and for cows with a Grade 1 femoral neuropathy. This

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trend was apparent for the cows with a Grade 2 femoral neuropathy although it was not shown to be statistically significant with the limited data available. The poor recovery of cows with Grade 3 and 4 femoral neuropathies suggests that these grades have poor prognoses unless there are better ways to manage them.

The recovery of cows with bilateral femoral neuropathies was associated with the degree of clinical dysfunction of the femoral nerves and by the way they were managed.

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Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage

Chapter 8. Classification and Grading of L6-S2 Nerve Plexus Damage

8.1 Introduction Neuropathies of the hindlimb in cattle are usually classified as femoral, obturator, sciatic, peroneal and tibial (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Smith-Maxie, 1997). The peroneal and tibial nerves are branches of the sciatic nerve and neuropathies of them usually refer to damage to the individual branches below their separation from the sciatic nerve (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Smith-Maxie, 1997) although peroneal damage can also be associated with dystocia (Constable, 2004, Vaughan, 1964).

The sciatic nerve, as shown in Figure 4.1, originates mainly from the last lumbar (L6) and first two sacral (S1, S2) components of the lumbosacral trunk (Getty, 1975). The L6 branch of the sciatic nerve courses closely to the ventral border of the wing of the sacrum and is tightly opposed to its acute ridge (Cox et al., 1975). It joins with the S1 and S2 ventral branches in the dorsal pelvis to form the sciatic nerve. It releases several branches, the ramus muscularis and rami musculares, which innervate the muscles of the pelvis and upper thigh (gluteus medius, gluteobiceps, semitendinosus, semimembranosus, adductor, quadratus femoris and gemelli) (Getty, 1975). These muscles serve as extensors of the hip and hock, and flexors of the stifle, and have a role in both abducting and adducting the limb and also extending the stifle (Getty, 1975).

The sciatic nerve bifurcates into the peroneal and tibial nerves at the mid-thigh region. The peroneal nerve courses anteriorly and laterally over the stifle, and passes behind the residual head of the fibula under the lateral condyle of the tibia. It innervates the muscles of the anterior aspect of the lower limb below the stifle. These muscles flex the hock and extend the digits (Getty, 1975). It divides into the superficial and deep common peroneal nerves, which further divide into to a number of branches, suppling sensory and motor function to the dorsal, dorso-lateral and dorso-medial aspects of the digits (Getty, 1975).

The tibial nerve passes between the two heads of the gastrocnemius and innervates the muscles that flex the stifle, extend the hock and flex the digits (Getty, 1975). It divides into the medial and lateral plantar nerves at the level of the hock, and further divides into progressively smaller nerves, innervating the plantar, planto-lateral and planto-medial

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Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage aspects of the digits (Getty, 1975). All of the sensory function to the hindlimb below the fetlock is supplied by the peroneal and tibial nerves (Hall, 1971).

When the sciatic nerve was experimentally sectioned in one leg of two calves at the level of the hip joint an “almost total paralysis” of the hind limb resulted. The stifle and hock joints were extended and the fetlock flexed, which left the dorsal pastern in contact with the ground. The only skin sensation present on the hind limb was at the medial thigh, which is innervated by the saphenous nerve, a branch of the femoral nerve (Vaughan, 1964). Damage to the sciatic nerve will result in a weakness to the hindlimb and the fetlock will be knuckled over (Constable, 2004, Parkinson et al., 2010). The patellar reflex may be normal or increased due to lack of tone in the hamstring group of muscles, which oppose the contraction of the quadriceps muscles (Constable, 2004).

When the peroneal nerve was experimentally sectioned at the level of the lateral head of the gastrocnemius, hyperextension of the hock and hyperflexion of the fetlock resulted with the anterior pastern resting on the ground. Full weight could be taken by the limb when the hoof was manually placed in the normal position but it immediately reverted to the abnormal position as soon as the first stride was taken (Vaughan, 1964). Sensation was reduced or lost to the dorsal aspect of the pastern (Keown, 1956, Parkinson et al., 2010). The peroneal nerve is susceptible to damage where it crosses the head of the fibula on the anterior lateral stifle, as it lies superficially in this position (Keown, 1956, Parkinson et al., 2010, Vaughan, 1964) but it can also be damaged during a difficult calving (Vaughan, 1964).

Sectioning of the tibial nerve where it passed between the two heads of the gastrocnemius resulted in the calves standing with hyperflexion of the hock and a forward knuckling of the fetlock. The sole of the hooves remained in contact with the ground (Vaughan, 1964), due to paralysis of the extensors of the hock and flexors (Parkinson et al., 2010). The gastrocnemius muscles atrophied in the weeks after the tibial nerve was sectioned (Vaughan, 1964).

Nerve damage to the sciatic and obturator nerves can occur from the passage of an oversized calf through the pelvic canal (Constable, 2004, Divers, 2004, Parkinson et al., 2010). It is presumed that the most likely site of damage to the sciatic nerve is to the L6 component where it passes under the ridge on the ventral border of the sacral wing (Cox and Martin, 1975). The sciatic nerve can also be damaged from intra-muscular injections (Divers, 2004, Parkinson et al., 2010), or from compression by neoplasia, abscess or pelvic fracture (Divers, 120

Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage

2004). The sciatic nerve can be damaged around the proximal femur by pressure in recumbent cattle (Cox, 1988). No specific mention of sciatic nerve damage from trauma to the back could be found in the literature but I have observed this during clinical veterinary practice. The peroneal nerve is susceptible to damage from trauma where it passes over the lateral stifle (Divers, 2004, Parkinson et al., 2010, Smith-Maxie, 1997) and it can also be damaged from dystocia when the trauma is to the part of the sciatic nerve from which the peroneal nerve arises (Constable, 2004, Vaughan, 1964). The tibial nerve is less susceptible to injury, as it is well protected by the gastrocneumius muscles (Constable, 2004, Parkinson et al., 2010, Vaughan, 1964), so tibial nerve injury is a “rare condition” in cattle (Vaughan, 1964) and requires extensive force to the gastrocneumius muscles to occur (Parkinson et al., 2010).

Cows with damage to the nerves emanating from the L6-S2 nerve plexus would show the variety of dysfunctions described above, and may include:

• Anterior and/or medial posture of a hindlimb when in the standing position

• Increased patellar reflex

• Weakness of the hindlimb involving the muscles innervated by these nerves

• Knuckling of the pastern

• Loss of sensation to the skin of the dorsal and/or plantar aspects of the pastern

• Hyperflexion of the hock and fetlock with the sole of the hoof placed normally on the ground (tibial paresis)

The femoral nerve in cattle forms from the ventral branch of the fifth lumbar nerve, with contributions from the fourth and sixth lumbar nerves. It innervates the quadriceps femoris, which is a strong extensor of the stifle joint and flexor of the hip. It gives branches to the psoas and iliacus muscles, which flex the hip and rotate the thigh; and the sartorius muscle, which flexes the hip and adducts the limb. The saphenous nerve, a branch of the femoral nerve, continues along the medial aspect of the thigh providing sensory function to the fascia and skin of the medial aspect of the leg to the level immediately distal to the tarsus (Getty, 1975). I diagnosed femoral nerve damage by a depressed or absent patellar reflex and a caudal tendency of the hindlimbs when attempting to stand.

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The obturator nerve forms from the continuation of the ventral branch of the fifth lumbar nerve, from a small branch from the ventral branch of the sixth lumbar and usually from one or two slender branches of the fourth lumbar nerve. It courses caudo-ventrally along the ilium to the cranial end of the obturator foramen. It splits into several branches to the adductor, pectineus, gracilis, quadratus femoris, obturatorius externus and internus muscles (Getty, 1975). The obturator nerve provides the main adductor function to the hind limb but the sciatic nerve also has some adductor function (Cox et al., 1975). I diagnosed obturator nerve damage in cows with an abducted hindlimb in the absence of other damage which could account for it, such as hip dislocation or torn adductor muscles.

Recumbent cows with signs of damage to the nerves formed from the L6-S2 nerve plexus were investigated in this part of the study. The aims were to propose new ways of describing the condition based on clinical presentation and to develop a grading system reflecting the level of damage and thus, a prediction of prognosis.

8.2 Materials and Methods Field studies of recumbent dairy cows were conducted in South Gippsland during two three- month periods in the winter calving months of 2011 and 2012. Recumbent cows were included in the study if they were bright, alert and responsive; and there was adequate history for them to be assessed properly. They were not required to be recumbent for more than one day to be included in this section. Calves and yearlings were excluded as were any cows with a history of prior recumbency in the previous thirty days.

Cows were initially attended by a veterinarian as soon as possible after the recumbency, ideally on the first day. The cows were thoroughly examined clinically to determine the cause of the recumbency and to detect any secondary damage. The conditions that the cows had been cared under prior to the first visit were recorded. Cows were revisited as many times as possible during their recumbency, often once or twice weekly. They were examined as close to the seventh day as was possible, if they were still being nursed and/or as close to the time of euthanasia as possible, if applicable. Cows were re-examined at each visit to detect secondary damage, judge progress and re-assess nursing conditions. The farmers were not charged for my visits.

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The initial cause of the recumbency was allocated into one of five broad groups: post- parturient hypocalcaemia (milk fever); protein-energy deficiency (Parkinson et al., 2010); calving paralysis; back injury; and ‘other’. This was based on the history provided by the farmer and examinations conducted by the initial attending veterinarian.

Thorough medical and musculo-skeletal clinical examinations were performed on each cow at each visit. The nerve function assessment was by:

• Flexor-withdrawal reflex, patellar reflex and muscle tone assessment in the recumbent position

o The ‘superficial’ flexor-withdrawal reflex was assessed by provoking the skin of the dorsal and plantar pastern with a hypodermic needle or electric cattle prodder to induce withdrawal of the leg from the noxious stimulus

o The ‘deep’ flexor-withdrawal reflex was assessed by squeezing the inter- digital area with hoof testers to induce withdrawal of the leg from the noxious stimulus

• Observations of postural responses were made when the cow tried to stand and when lifted with hip clamps or other suitable device, with the use of a chest strap if they failed to bear weight on the forelimbs

• Flexor-withdrawal reflex and muscle tone assessment were repeated in the elevated position

Any abnormality that was diagnosed at the initial visit that was not consistent with the primary cause of the recumbency was regarded as secondary damage. Any damage diagnosed at subsequent visits that was not apparent at the initial visit was regarded as secondary damage.

All secondary damage was assessed to determine if it was important from a clinical perspective. Clinically important secondary damage was defined as secondary damage that contributed to the recumbency in its own right or delayed or prevented recovery from the original recumbency.

The conditions the cows were cared under during their recumbency were recorded at each visit. Most of the cows in this chapter were part of the larger study of 218 cows that had

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been recumbent for more than one day (Chapter 5). In this larger study, it was found that the occurrence of clinically important secondary damage had a greater influence on outcome than the original cause of the recumbency. It was also shown that the level of nursing care provided to the recumbent cows significantly affected their chance of recovery (Chapter 6). The same definitions of ‘satisfactory’ and ‘unsatisfactory’ nursing care are used in this chapter.

Outcome for the cows was either recovered or death:

1. Recovered was defined as being able to consistently stand independently and walk around for at least the following two days

2. Death was either from: euthanasia, which was at the farmers’ discretion, unless I considered the animal was suffering welfare issues; or an acute medical condition where they were found dead

From the data collected during the study, a subset of cows with damage predominately to the nerves emanating from the L6-S2 nerve plexus (sciatic, peroneal, tibial, cranial gluteal and caudal gluteal nerves) was formed. The group was defined as having predominately L6- S2 nerve plexus injuries, as either primary damage or secondary damage in the absence of other significant unresolved primary conditions. Cows with concurrent damage to the femoral or obturator nerves were included unless the clinical syndrome presented predominately as a dysfunction of these nerves. Cows with clinical signs of major structural damage to the vertebrae or pelvis at the initial visit were excluded. Cows with secondary L6- S2 nerve plexus injuries were included only if their primary condition, such as milk fever, had been resolved.

These selection criteria were used to limit the data set to those with damage predominately to the nerves emanating from the L6-S2 nerve plexus in order to analyse this condition independently. The different clinical presentations of these neuropathies were noted and their occurrence recorded. Post mortem examinations were performed on some cows with different neurological presentations to observe the gross and histological changes.

The anatomy, function and dysfunction of the hindlimb nerves, as described in the Introduction, were used when determining the particular neuropathy for each cow.

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It became necessary during the course of the research project to develop a way to describe the different clinical presentations of L6-S2 plexus damage, so I proposed a two digit code, ‘x-y’, as shown in Table 8.1. The code was used to describe the more severely affected hindlimb and for simplicity, no account was taken of the lesser affected hindlimb. The first digit, ‘x’, describes the degree of damage to the proximal branches of the L6-S2 nerve plexus, which supply the pelvic and hamstring group of muscles. The second digit, ‘y’, describes the level of damage to the distal branches of the L6-S2 nerve plexus, which innervate the lower part of the hindlimb (peroneal and tibial nerves). For example, cows that only showed an increased patellar reflex were coded 1-0 and cows that only showed knuckling of the hindlimb when lifted with positive superficial and deep flexor-withdrawal reflexes were coded 0-1. Cows that showed both of these traits were coded 1-1. The table does not include any complications from femoral or obturator nerve damage or incidental tibial paresis involvement.

Cows with tibial paresis display hyperflexion of the hock and fetlock with the sole of the hoof placed normally on the ground. Whilst the tibial nerve originates from the L6-S2 nerve plexus it is regarded as a separate neuropathy to the ones described by the proposed new classification.

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Table 8.1. Codes for the different presentations of damage to the branches of the L6-S2 plexus as proposed by this thesis Code Clinical findings 1-0 Increased patellar reflex 2-0 Moderate anterior and/or medial posture when lifted 3-0 Marked anterior and/or medial posture when lifted 0-1 Knuckling of pastern with: positive superficial flexor-withdrawal reflex dorsal pastern positive superficial flexor-withdrawal reflex plantar pastern positive deep flexor-withdrawal reflex 0-2 Knuckling of pastern with: negative superficial flexor-withdrawal reflex dorsal pastern positive superficial flexor-withdrawal reflex plantar pastern positive deep flexor-withdrawal reflex 0-3 Knuckling of pastern with: negative superficial flexor-withdrawal reflex dorsal pastern negative superficial flexor-withdrawal reflex plantar pastern positive deep flexor-withdrawal reflex 0-4 Knuckling of pastern with: negative superficial flexor-withdrawal reflex dorsal pastern negative superficial flexor-withdrawal reflex plantar pastern negative deep flexor-withdrawal reflex 1-1 Clinical findings of codes 1-0 and 0-1 1-2 Clinical findings of codes 1-0 and 0-2 1-3 Clinical findings of codes 1-0 and 0-3 1-4 Clinical findings of codes 1-0 and 0-4 2-1 Clinical findings of codes 2-0 and 0-1 2-2 Clinical findings of codes 2-0 and 0-2 2-3 Clinical findings of codes 2-0 and 0-3 2-4 Clinical findings of codes 2-0 and 0-4 3-1 Clinical findings of codes 3-0 and 0-1 3-2 Clinical findings of codes 3-0 and 0-2 3-3 Clinical findings of codes 3-0 and 0-3 3-4 Clinical findings of codes 3-0 and 0-4

The weight bearing ability of the weaker hindlimb when lifted at the first visit was estimated. This was judged on clinical impressions whilst observing the cow supported in the elevated position by a suitable means, such as a Bagshaw hip clamp. It was subjective in nature and not meant to be a rigid ‘scientific’ measure but it was felt that it could have some merit, particularly for farmers trying to judge the severity of the condition. The aim was to try to assess if the cow’s weaker leg could support more than approximately 75% of its normal weight, so it could be allocated to one of two groups: ‘satisfactory’ or

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‘unsatisfactory’. ‘Satisfactory’ was defined as the weaker hindlimb being able to bear at least 75% of its normal weight and ‘unsatisfactory’ was defined as the weaker hindlimb unable to bear at least 75% of its normal weight. The categories required the cow to be lifted and were subjective but should be reasonably repeatable between different assessors.

One aim of the research was to try to use the grades to predict the chance of recovery. I proposed a three-tiered scale reflecting the degree of damage and hence the corresponding prognosis. Group 1, (‘good’) contains L6-S2 plexus presentations with mild damage and carry a reasonable chance of recovery and a relatively short recovery time period. The L6-S2 grades in Group 2 (‘moderate’) have an intermediate level of damage and a guarded prognosis, whereas the grades in Group 3 (‘poor’) are more severely affected and have a poor prognosis and if recovery was to occur, it would be over an extended time period.

The grades were allocated into the three prognostic groups after retrospective analysis of the outcome data for each cow of each group. It was performed by two means: ‘statistical allocation’ and ‘clinical judgment’. ‘Statistical allocation’ was based purely on comparing recovery data at day 3, 7 and final for each grade to the overall averages and to the other grades. The groups based on ‘clinical judgement’ were allocated after taking into consideration clinical impressions of the level of damage, predisposition for clinically significant secondary damage despite satisfactory nursing care and weight bearing ability of the weaker leg when first lifted, in addition to the recovery data. This is covered in more detail in the discussion section.

8.2.1 Statistical analysis A case cow was defined as not recovered by the relevant time period and a control cow as recovered by that relevant time period. Logistic regression and the odds ratio (OR), 95% confidence interval (CI) and Wald P value were used to measure the strength of association between risk factors and case/control status. If any cell in a 2 X 2 table was zero, 0.5 was added to each cell frequency before the calculation to report an adjusted odds ratio and 95% CI (Fleiss et al., 2003). The Cochran-Armitage test for linear trend (Armitage, 1955, Cochran, 1954) was used to test for a component of linear trend between the relevant L6-S2 grade and the proportion of cows with a given binary outcome. StatXact software was used to calculate the exact P value for the Cochran-Armitage test for linear trend. StatXact 10

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(Cytel, Cambridge, MA) and WinPepi 11.48 (Abramson, 2011) software were used for the analyses. Two-sided P values < 0.05 were regarded as statistically significant.

8.3 Results The selection criteria for inclusion in this study were satisfied by 103 cows, of which 96 (93%) cows were from the 218 cows from Chapter 5, as they were recumbent for more than one day. There was one other cow with L6-S2 plexus injury from the cohort of 218 cows but she was excluded from this chapter as she was not first seen by me until she had been recumbent for nine days, thus it was not possible to assess the grade of her L6-S2 neuropathy. The extra seven (7%) cows had recovered in less than one day so were ineligible for the larger, downer cow study. Calving paralysis was the primary cause of the recumbency in 95 (92%) cows and five (5%) had a primary back injury, mainly as a result of a mounting injury. Two (2%) cows had slipped in the dairy and remained recumbent on the concrete for several hours, which may have caused compression of the sciatic nerve where it courses around the proximal femur (Van Metre, 2001). One (1%) cow initially became recumbent from milk fever and failed to rise after her calcium deficiency had been corrected. Her sciatic nerve damage presumably occurred when she struggled to rise or from swelling within the muscles causing compression of the nerve.

By day 3, 18/103 (17%) cows had recovered, 31 (30%) cows had recovered by day 7 and 40 (39%) cows eventually recovered. For the 75 cows that were nursed at a satisfactory level, 15 (20%) cows had recovered by day 3, 28 (37%) cows had recovered by day 7 and 37 (49%) cows eventually recovered.

The occurrence of the various grades of L6-S2 nerve plexus injuries are shown in Table 8.2. Concurrent femoral or obturator nerve damage and incidental tibial paresis are not listed in this table. Please refer to Table 8.1 for an explanation of the L6-S2 codes.

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Table 8.2. Occurrence of the different combinations with damage to the other presentations of L6-S2 damage with or without concurrent incidental obturator nerves of the hindlimb, being three cows and/or femoral nerve damage or tibial with L6-S2 damage, two with L6-S2 and paresis in 103 cows obturator nerve damage, one with L6-S2, L6-S2 code n % obturator and femoral nerve damage and 0-1 6 6 another with L6-S2 and femoral nerve 0-2 4 4 damage.

0-3 2 2 Concurrent, incidental damage to the

0-4 1 1 femoral nerve was found in 12/103 (12%) cows with or without incidental damage 1-0 10 10 to the obturator and with or without tibial 1-1 11 11 paresis. There were a wide variation in 1-2 4 4 clinical presentation between the 1-3 5 5 different cows due to different

1-4 5 5 combinations of affected nerves: five (5%) cows had L6-S2 nerve damage with 2-0 19 18 femoral nerve damage, a sixth (1%) cow 2-1 21 20 had L6-S2 damage, femoral nerve damage 2-2 2 2 and tibial paresis, five (5%) cows had L6- 2-3 0 0 S2 nerve damage, femoral and obturator

2-4 3 3 nerve damage and one (1%) cow had L6-

3-0 4 4 S2, femoral and obturator nerve damage with tibial paresis. 3-1 5 5 Concurrent, incidental damage to the 3-2 0 0 obturator nerve was found in 28/103 3-3 0 0 (27%) cows. Twenty (19%) cows had L6-S2 3-4 1 1 nerve damage with obturator nerve Total 103 100 damage, two (2%) cows had L6-S2, obturator nerve damage and tibial paresis, Of the 103 cows, seven (7%) cows also five (5%) cows had L6-S2 nerve damage, had tibial paresis. This occurred in various obturator and femoral nerve damage and

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another (1%) cow had L6-S2, obturator and femoral nerve damage with tibial paresis.

The influence on recovery of the various combinations of femoral and obturator neuropathies and of incidental involvement of tibial paresis was analysed by comparing recovery by day 7 of cows with L6-S2 nerve plexus damage with the other neuropathies to the cows with L6-S2 nerve plexus damage without the other neuropathies. These analyses are shown in Table 8.3.

Table 8.3. Day 7 recovery of 103 cows with L6-S2 plexus damage with or without obturator nerve damage, with or without femoral nerve damage and with or without tibial paresis Type of nerve damage Recovered OR 95% CI P by day 7 n n % L6-S2 with any other type 37 8 22 0.5 0.2-1.3 0.16 L6-S2 without any other type 66 23 35 1 [REF] Any combination with obturator 28 7 25 0.7 0.3-1.9 0.49 Any combination without obturator 75 24 32 1 [REF] Any combination with femoral 12 2 17 0.4 0.1-2.1 0.29 Any combination without femoral 91 29 32 1[REF] Any combinations with tibial paresis 7 1 14 0.4 0.04-3.2 0.36 Any combination without tibial paresis 96 30 31 1 [REF]

There was no significant difference in recovery by day 7 for cows with L6-S2 nerve plexus damage when they also had concurrent incidental obturator nerve damage, concurrent incidental femoral nerve damage or concurrent tibial paresis.

The day 3, day 7, final recovery, occurrence of clinically important secondary damage, including secondary hip dislocation and of secondary hip dislocation separately, for the various grades of L6-S2 nerve plexus damage were analysed and the results displayed in Table 8.4. Refer to Table 8.1 for an explanation of the L6-S2 codes. As there was no significant difference in recovery for the cows with L6-S2 nerve plexus damage that had concurrent obturator or femoral nerve damage or concurrent tibial paresis, the recovery of the cows with the various presentations of L6-S2 nerve plexus damage were analysed whether they had the other concurrent neuropathy/ies or not.

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Table 8.5. Day 3, 7 and final recovery for 26 cows with various grades of L6-S2 plexus damage irrespective of concurrent femoral or obturator nerve damage or tibial paresis that did not suffer any clinically important secondary damage Grade of L6-S2 Recovered Recovered Eventually neuropathy by day 3 by day 7 recovered Code n % n % n % n % 1-0 2 8 1 50 2 100 2 100 2-0 5 19 3 60 4 80 4 80 0-1 2 8 0 0 2 100 2 100 1-1 2 8 1 50 1 50 2 100 1-3 2 8 1 50 1 50 1 50 2-1 11 42 6 55 9 82 11 100 2-2 1 4 0 0 1 100 1 100 3-41 1 4 0 0 0 0 0 0 Total 26 100 12 46 20 77 23 88 1This cow was destroyed on the second day due to her poor prognosis.

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Recovery data for the cows that did not suffer any clinically important secondary damage are listed in Table 8.5. There were 26/103 (25%) cows that fitted this criterion. By day 7, 20/26 (77%) cows that did not suffer any clinically significant secondary damage had recovered compared to 10/77 (13%) cows that did suffer clinically important secondary damage (OR 22.3; 95% CI 7.2-69.0; P < 0.0001).

Chapter 6 demonstrated that the quality of the nursing care had a major influence on the occurrence of clinically important secondary damage and on recovery, so Table 8.6 shows the day 3, 7 and final recoveries of the 75 cows that were nursed at a satisfactory level. The occurrence of clinically important secondary damage is also shown in this table.

Table 8.6. Day 3, 7 and final recovery for 75 cows with various grades of L6-S2 plexus damage irrespective of concurrent femoral or obturator nerve damage or tibial paresis that were nursed overall at a satisfactory level L6-S2 neuropathy Recovered Recovered Eventually Secondary by day 3 by day 7 recovered damage1 Code n % n % n % n % n % 1-0 6 8 3 50 4 67 4 67 4 67 2-0 17 23 5 29 7 41 9 53 12 71 3-0 2 3 0 0 0 0 1 50 2 100 0-1 4 5 0 0 2 50 2 50 2 50 0-2 2 3 0 0 0 0 1 50 2 100 0-3 1 1 0 0 0 0 0 0 1 100 0-4 1 1 0 0 0 0 0 0 1 100 1-1 9 12 1 11 2 22 4 44 7 78 1-2 3 4 0 0 0 0 0 0 3 100 1-3 1 1 0 0 0 0 0 0 0 0 1-4 2 3 0 0 0 0 0 0 2 100 2-1 18 24 6 33 11 61 14 78 8 44 2-2 1 1 0 0 1 100 1 100 0 0 2-4 2 3 0 0 1 50 1 50 2 100 3-1 5 7 0 0 0 0 0 0 5 100 3-42 1 1 0 0 0 0 0 0 0 0 Total 75 100 15 20 28 37 37 49 51 68 1Clinically important secondary damage, including secondary hip dislocation. 2This cow was destroyed on the second day due to her poor prognosis.

Of the 28 cows nursed unsatisfactorily, only three (11%) cows recovered with all three recovering by day three. Only 2/28 (7%) cows nursed unsatisfactorily did not suffer any clinically important secondary damage and both these cows recovered. The odds of

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recovery increased eight-fold and the odds of suffering clinically important secondary damage decreased six-fold when cows were nursed satisfactorily compared to unsatisfactorily (OR 8.1; 95% CI 2.3-29.2; P = 0.001), (OR 6.1; 95% CI 1.3-27.9; P = 0.019), respectively.

Data for the weight bearing ability of the weaker hindlimb when first lifted by L6-S2 grade is listed in Table 8.7 and by recovery at day 3, 7 and final recovery in Table 8.8.

Table 8.7. Weight bearing ability of the weaker hindlimb when first lifted for 95 cows with L6-S2 injury according to their L6-S2 grade Grade of L6-S2 injury Weight bearing ability2 Number of cows lifted1 Unsatisfactory Satisfactory <75% ≥75% Code n % n % n % 1-0 7 7 1 14 6 86 2-0 20 21 3 15 17 85 3-0 3 3 1 33 2 67 0-1 6 6 2 33 4 67 0-2 4 4 2 50 2 50 0-3 1 1 1 100 0 - 0-4 1 1 1 100 0 - 1-1 11 12 6 55 5 45 1-2 4 4 3 75 1 25 1-3 3 3 2 67 1 33 1-4 4 4 4 100 0 - 2-1 21 22 4 19 17 81 2-2 2 2 1 50 1 50 2-4 2 2 1 50 1 50 3-1 5 5 3 60 2 40 3-4 1 1 1 100 0 - Total 95 100 36 38 60 63 1Only 95 of the 103 cows were lifted. 2Satisfactory weight bearing ability is defined as being able to support at least 75% of the weight on the weaker hindlimb when lifted.

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Table 8.8. Weight bearing ability of the weaker hindlimb when lifted at first visit differentiated into at least 75% or less than 75% and recovery by day 3, 7 and final for the 95 cows with L6-S2 injury that were lifted Weight bearing ability of Number Recovered by Recovered by Eventually the weaker hindlimb of cows day 3 day 7 recovered when lifted n n % n % n % Satisfactory (≥75%) 59 17 29 25 42 31 53 Unsatisfactory (<75%) 36 1 3 6 17 9 25 Total 95 18 19 31 33 40 42 Odds ratio 14.2 3.7 3.3 95% CI 1.8-112 1.3-10.2 1.3-8.3 P 0.012 0.012 0.010

Clinical allocation of the L6-S2 plexus grades into three groups of severity was based on the recovery data presented in Table 8.4, Table 8.5 and Table 8.6, the cows’ weight bearing ability at the first visit (Table 8.7) and the propensity for each grade to suffer clinically important secondary damage, as shown in Table 8.4 and Table 8.6. Statistical allocation of the L6-S2 plexus grades into three groups of severity was based only on the recovery data. The L6-S2 grades allocated into the three prognostic groups using the two methods are shown in Table 8.9. The only difference is Grade 1-1, which is in the moderate prognostic group statistically but in the mild group clinically.

Table 8.9. L6-S2 grades allocated into three groups of severity based on statistical and clinical judgement Degree of severity L6-S2 grades based on L6-S2 grades based on statistical results clinical judgment Mild 0-1, 1-0, 2-0, 2-1 0-1, 1-0, 2-0, 2-1 1-1 Moderate 0-2, 1-2, 2-2, 0-2, 1-2, 2-2 1-1 Severe 0-3, 0-4, 1-3, 1-4, 2-3, 0-3, 0-4, 1-3, 1-4, 2-3, 2-3, 3-0, 3-1, 3-2, 3-3, 3-4 2-3, 3-0, 3-1, 3-2, 3-3, 3-4

The combined day 3, day 7 and final recovery of the cows in each of the three statistically based prognostic groups are shown in Table 8.10. They are shown for the full data set of 103 cows and for the 75 cows that were nursed at a satisfactory level. The ability to bear at least

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75% of weight by the weaker hindlimb for cows in the three groups is also shown in this table. The Cochran-Armitage tests for trend between the three groups for each of these measures are listed.

By day 3, 16/58 (28%) cows in the mildly affected group had recovered compared to 2/45 (4%) cows in the other two groups (OR 8.2; 95% CI 1.8-37.8; P = 0.007).

By day 7, 26/58 (45%) cows in the mildly affected group had recovered compared to 5/45 (11%) cows in the other two groups (OR 6.5; 95% CI 2.2-18.8; P = 0.001).

The combined day 3, day 7 and final recovery of the cows in each of the three clinically based prognostic groups are shown in Table 8.11. They are shown for the full data set of 103 cows and for the 75 cows that were nursed at a satisfactory level. The ability to bear at least 75% of weight by the weaker hindlimb for cows in the three groups is also shown in this table. The Cochran-Armitage tests for trend between the three groups for each of these measures are listed.

Table 8.10. Day 3, 7 and final recovery for the 103 cows with damage to the L6-S2 plexus and for those 75 cows that were nursed satisfactorily and weight bearing ability of the weaker hindlimb on the first visits for the three statistically based prognostic groups Combined grades Mild Moderate Severe Total C/A trend1 Recovered by day 3: all cows 16/58 2/21 0/24 18/103 P = 0.002 28% 10% 0% 18% Recovered by day 7: all cows 26/58 4/21 1/24 31/103 P < 0.001 45% 19% 4% 30% Eventually recovered: all cows 31/58 7/21 2/24 40/103 P < 0.001 53% 33% 8% 39% Recovered by day 3: cows nursed 14/45 1/15 0/15 15/75 P = 0.004 satisfactorily 31% 7% 0% 20% Recovered by day 7: cows nursed 24/45 3/15 1/15 28/75 P < 0.001 satisfactorily 53% 20% 7% 37% Eventually recovered: cows 29/45 6/15 2/15 37/75 P < 0.001 nursed satisfactorily 64% 40% 13% 49% Initial satisfactory weight bearing 44/55 9/21 6/19 59/95 P < 0.0001 ability of weaker leg2,3 80% 43% 32% 62% 1Cochran-Armitage test for trend. 2Able to bear at least 75% of their normal weight on their weaker hindlimb when lifted. 3Only 95 cows were lifted.

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Table 8.11. Day 3, 7 and final recovery for the 103 cows with damage to the L6-S2 plexus and for those 75 cows that were nursed satisfactorily and weight bearing ability of the weaker hindlimb on the first visits for the three clinically based prognostic groups Combined grades Mild Moderate Severe Total C/A trend1 Recovered by day 3: all cows 17/69 1/10 0/24 18/103 P = 0.005 25% 10% 0% 18% Recovered by day 7: all cows 28/69 2/10 1/24 31/103 P = 0.001 41% 20% 4% 30% Eventually recovered: all cows 35/69 3/10 2/24 40/103 P < 0.001 51% 30% 8% 39% Recovered by day 3: cows nursed 15/54 0/6 0/15 15/75 P = 0.010 satisfactorily 28% 0% 0% 20% Recovered by day 7: cows nursed 26/54 1/6 1/15 28/75 P = 0.002 satisfactorily 48% 17% 7% 37% Eventually recovered: cows 33/54 2/6 2/15 37/75 P = 0.001 nursed satisfactorily 61% 33% 13% 49% Initial satisfactory weight bearing 49/66 4/10 6/19 59/95 P < 0.0001 ability of weaker leg2,3 74% 40% 32% 62% 1Cochran-Armitage test for trend. 2Able to bear at least 75% of their normal weight on their weaker hindlimb when lifted. 3Only 95 cows were lifted.

There were 41 cows with Grade 2-0 and 2-1 L6-S2 plexus damage. A normal patellar reflex was recorded in 11 cows, increased in 23 cows and not recorded in the other seven cows. The day 7 recovery of the 23 cows with an increased patellar reflex was 12 (52%) cows compared to 3/11 (27%) cows with normal patellar reflexes. The difference was not statistically significant (OR 2.9; 95% CI 0.6-13.8; P = 0.18).

Secondary hip dislocation was a common complication to the cows in this study with an occurrence of 23/103 (22%). The different combinations of neuropathies were analysed to ascertain if there were certain types of neuropathies that were more prone to secondary hip dislocation. The results are shown in Table 8.12.

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Table 8.12. Risk of secondary hip dislocation with grade of L6-S2 plexus damage in 103 cows Type of neuropathy Secondary hip OR 95% CI P dislocation n n % L6-S2 with obturator nerve damage 28 10 36 2.7 1.0-7.0 0.051 L6-S2 without obturator nerve damage 75 13 17 1[REF] Proximal and distal branches of L6-S2 57 10 18 0.5 0.2-1.4 0.20 Only proximal or only distal branches 46 13 28 1[REF] of L6-S2 Only proximal branches of L6-S2 33 5 15 0.5 0.2-1.5 0.24 Only proximal and distal or only distal 70 18 26 1[REF] branches of L6-S2 Only distal branches of L6-S2 13 8 62 8.0 2.3-27.9 0.001 Only proximal and distal or only 90 15 17 1[REF] proximal branches of L6-S2 L6-S2 grades 0-1 and 1-1 17 8 47 4.2 1.4-12.7 0.011 All other L6-S2 grades 86 15 17 1[REF] All L6-S2 with femoral nerve 12 1 8 0.3 0.03-2.3 0.24 All L6-S2 without femoral nerve 91 22 24 1[REF] All L6-S2 with tibial paresis 7 0 0 0.21 0.01-3.8 0.3 All L6-S2 without tibial paresis 96 23 24 1[REF] Total 103 23 22 1Adjusted odds ratio.

8.3.1 Post mortem findings Post mortem examinations were performed on three of the calving paralysis cows, one of which displayed the clinical presentations of each of the three groups: cow 2855 showed clinical symptoms predominately of marked anterior/medial tendency of the right hindlimb consistent with damage to the nerve roots supplying the upper limb. She had an occasional knuckling of the fetlock consistent with some mild damage to the distal branches of the L6- S2 nerve plexus and was graded L6-S2 3-1, as shown in Figure 8.1 but her main presentation was of damage to the proximal branches of the L6-S2 nerve plexus; cow 3454 showed moderate damage to the right lower limb with knuckling of the fetlock and loss of sensation to dorsal pastern, without L6-S2 nerve plexus involvement on the left side, as shown in Figure 8.2. She was graded L6-S2 0-2 and was an example of the group of cows presenting with damage to the distal branches of the L6-S2 nerve plexus; cow Z66 showed total paralysis clinically with upper limb dysfunctions and an absence of flexor-withdrawal reflexes of both hindlimbs, as shown in Figure 8.3. She was graded L6-S2 1-4 on the left hind

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and L6-S2 2-4 on the right hind. She was an example of the group of cows presenting with damage to both the proximal and distal branches of the L6-S2 nerve plexus.

The gross changes evident in cow 2855 were to the right S1 ventral roots with some mild injury to S2 but no apparent damage to L6, as shown in Figure 8.4. Histologically, S1 showed severe changes within the nerve trunks consistent for chronic widespread Wallerian degeneration. S2 sections were within normal limits histologically. There were no histological changes to the L6 ventral branch.

Post mortem changes in cow 3454 were haemorrhage, swelling and discoloration of the right L6 and S1 ventral branches, as shown in Figure 8.5. Parts of the L6 nerve trunk were severed with discontinuities in the nerve. There were no gross changes to the left L6-S2 plexus. Histologically, the right L6 and S1 ventral branches showed extensive oedema and haemorrhage of adipose and connective tissues adjacent to the nerves and extension of oedema into some nerves. Histological changes were more severe in sections taken from S1 but similar changes were seen in the histological samples taken from areas of L6 where the nerves appeared intact macroscopically.

The left L6 ventral branch of cow Z66 seemed to be crushed and macerated. This nerve was obscured by a large haematoma and the distal part of L6 was severed at this point. Left S1 also had obvious gross changes of severe haemorhage along its first 3 cm, as shown Figure 8.6. Histologically, sections of the left S1 nerve had extensive acute haemorrhage into connective and adipose tissues. There was congestion and endothelial swelling of vessels within nerve trunks, extensive haemorrhage into the epineurium and fibrinoid necrosis of the walls of many vessels in the epineurium. The right side had injuries to the L6 and S1 ventral branches grossly and histologically, with extensive haemorrhage into adipose tissue and muscle and ring haemorrhages into the nerve that surrounded many of the nerve fascicles.

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Figure 8.1. Cow 2855 with anterior right hindlimb posture

Figure 8.2. Cow 3454 with knuckling of right hindlimb

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Figure 8.3. Cow Z66 with total paralysis of both hindlimbs

Figure 8.4. Cow 2855 showing damage to the right side S1 and S2 ventral branches without damage to L6

L6 S2

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Figure 8.5. Cow 3545 showing damage to the right side L6 and S1 ventral branches

Figure 8.6. Cow Z66 showing site of damaged L6 root and forceps pointing to left S1 root

Site of L6

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8.4 Discussion

8.4.1 Grading of damage to the L6-S2 nerve plexus Neuropathies of the hindlimb in cattle are traditionally differentiated into femoral, obturator, sciatic, peroneal and tibial nerve damage. Femoral neuropathies have quadriceps dysfunction so present with loss of stifle extension, a caudal tendency of the hindlimbs when trying to rise and reduced or absent patellar reflex. Obturator neuropathies have loss of adduction so present with a wide-based stance. These two neuropathies are usually distinct and easy to categorize. Tibial paresis has a characteristic posture and is well defined.

Sciatic and peroneal neuropathies are less distinct as both can present with knuckling of the pastern. Traditionally, the ‘sciatic’ classification would apply when the entire sciatic nerve is affected. Severe damage to the sciatic nerve would result in recumbency from a weakness of the hindlimb and knuckling of the fetlock (Constable, 2004, Parkinson et al., 2010, Smith- Maxie, 1997). Cows with partial damage to the sciatic may be able to stand and would display a knuckled fetlock and dropped hock stance (Parkinson et al., 2010, Smith-Maxie, 1997). However, this description is the same as that used to describe peroneal damage (Parkinson et al., 2010, Smith-Maxie, 1997). The ‘peroneal’ classification usually refers to damage to the peroneal nerve after it divides from the sciatic nerve, commonly over the lateral stifle (Constable, 2004, Divers, 2004, Parkinson et al., 2010, Smith-Maxie, 1997). However, the peroneal nerve can also be damaged during dystocia (Constable, 2004, Vaughan, 1964) where the axons damaged are only those axons that form the peroneal nerve (Vaughan, 1964). There is overlap between these two syndromes, which can make this classification confusing. Rather than thinking of them in terms of sciatic or peroneal syndromes, this study proposes referring to them as neuropathies of the L6-S2 nerve plexus. The classification includes neuropathies of the cranial gluteal, caudal gluteal, sciatic, peroneal and tibial nerves although cows with classical ‘tibial paresis’ remain as a separate entity.

Tibial paresis is characterised by cows with a distinctive hyper-flexion of the hock, a forward flexion of the fetlock and the sole of the hoof placed on the ground (Parkinson et al., 2010). Tibial paresis is a unique neuropathy and can occur solely or in combination with other nerve damage. Cows suffering only with tibial paresis, either uni- or bilaterally, can rise unassisted and walk displaying the characteristic gait. This was observed in one cow during

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the study but as she was not recumbent she was not included in the data set. Cows with tibial paresis concurrent with other neuropathies will display the characteristic tibial stance in addition to the clinical signs of the other neuropathy, such as anterior/medial posture if the proximal branches of the L6-S2 plexus have been affected. Cows with tibial paresis were observed to retain sensation to the plantar pastern so it seems to be a motor dysfunction only. This differentiates it from cows that showed loss of sensation to the plantar aspects of the fetlock, which is innervated by the tibial nerve (Getty, 1975). The proposed new classification system takes tibial nerve sensory loss into account by using the codes x-3 or x- 4 and is not to be confused with tibial paresis. The term ‘tibial paresis’ would remain alongside the proposed new classifications as a distinct entity.

Tibial paresis, as an incidental finding, was observed in 7/103 (7%) cows with L6-S2 plexus damage. This is in contradiction to Vaughan (1964) who considered injury to the tibial nerve to be “rare”. It was associated with calving paralysis in the cows in this study, and I speculate that the damage to the tibial nerve occurred to its roots in the pelvic canal from the dystocia rather than to the peripheral nerve in the lower limb. This differs from the literature where it is considered to be associated with extensive trauma to the gastrocneumius muscle (Divers, 2004, Parkinson et al., 2010, Smith-Maxie, 1997, Vaughan, 1964). Further research on the aetiology of this condition is required.

Neuropathies of the cranial and caudal gluteal nerves, which seem to be overlooked when neuropathies of the hindlimb are described, are also included in the new system as they originate from the L6-S2 nerve plexus.

I observed cows in this study with L6-S2 nerve plexus damage to present in three different ways:

1. Dysfunction to the nerves innervating the muscles of the upper hindlimb; being the pelvic and caudal thigh muscles. These cows showed either: an increased patellar reflex, due to weakness of the hamstring muscles, which oppose the contraction of the quadriceps muscle induced by the reflex; and/or an anterior and/or medial posture when standing after being lifted. This posture is due to an inability to extend and/or abduct/rotate the hip. The cranial gluteal, caudal gluteal and rami musculares nerves innervate the muscles with these functions. These nerves originate from the L6-S2 nerve plexus and as they supply the muscles of the upper or proximal hindlimb 143

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this study proposes that they are described as the proximal branches of the L6-S2 nerve plexus. Three grades of severity are proposed:

a. Grade 1: increased patellar reflex only

b. Grade 2: moderate anterior and/or medial posture when standing

c. Grade 3: severe anterior and/or medial posture when standing

Grade 2 was defined as a tendency for the hindlimb to be in an anterior and/or medial position when the cow is lifted but where the cow was still able to correct this tendency and assume a normal posture, whereas Grade 3 was defined as the hindlimb usually being in an anterior and/or medial position with the cow not readily able to correct the abnormality to regain normal posture. Grade 3 is a more severe form of Grade 2. Grade 1 and 2 are not linear as they describe mild damage to different branches of the L6-S2 nerve plexus and they may occur concurrently or independently. Some Grade 2 and 3 cows will have an increased patellar reflex and some will have a normal patellar reflex.

2. Dysfunction to the lower part of the hindlimb with or without sensory loss to the pastern. The lower hindlimb is innervated by the peroneal and tibial nerves, distal branches of the sciatic nerve. These cows displayed knuckling of the hindlimb when lifted with the dorsal aspect of the pastern in contact with the ground with/or without sensory loss to the pastern. This study proposes that these types of syndromes are described as neuropathies of the distal branches of the L6-S2 nerve plexus. I observed a pattern of progressive sensory loss, which gave rise to four proposed grades of increasing severity:

a. Grade 1: positive superficial flexor-withdrawal reflex on dorsal and plantar pastern with positive deep flexor-withdrawal reflex

b. Grade 2: negative superficial flexor-withdrawal reflex on dorsal pastern with positive superficial flexor-withdrawal reflex on plantar pastern and positive deep flexor-withdrawal reflex

c. Grade 3: negative superficial flexor-withdrawal reflex on dorsal and plantar pastern with positive deep flexor-withdrawal reflex

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d. Grade 4: negative superficial flexor-withdrawal reflex on dorsal and plantar pastern with negative deep flexor-withdrawal reflex

3. Dysfunction of both groups one and two and this study proposes they are referred to as neuropathies of the proximal and distal branches of the L6-S2 nerve plexus. They occurred in any possible combination of the different grades of the proximal and distal L6-S2 plexus neuropathies, as shown in Table 8.1.

Under the current classification cows in the third presentation group fit the ‘sciatic’ definition as the entire nerve is affected. Cows with the symptoms of the second group could be currently described as either a peroneal or sciatic neuropathy. Some cows with symptoms of the first presentation group may mistakenly not be diagnosed as sciatic due to the absence of knuckling of the fetlock, which is normally associated with sciatic damage (Constable, 2004, Parkinson et al., 2010). The new classification proposed by this study is less confusing.

Some cows presented with knuckling of the fetlock and loss of sensation to the dorsal and plantar aspects of the fetlock. The peroneal nerve supplies sensory function to the dorsal pastern and the tibial nerve supplies it to the plantar pastern (Getty, 1975), so these cows had both peroneal and tibial nerve damage. Under the current system they would be classified as a sciatic neuropathy but if clinical examination did not include sensory assessment at the plantar pastern they could be wrongly classified as a peroneal neuropathy. The proposed classification helps overcome confusion between the overlap of sciatic and peroneal neuropathies by describing them both as L6-S2 plexus neuropathies. The grading system records damage to the tibial nerve that manifests as sensory loss to the plantar pastern by using the codes x-3 and x-4 rather than using the term ‘tibial nerve damage’. This is to avoid confusion with the syndrome ‘tibial paresis’, which I consider to be a motor dysfunction of the gastrocneumius muscle.

Cows presenting with an inability to extend and/or abduct the hindlimb would have dysfunction of the gluteobiceps and/or gluteus medius muscles. These muscles are innervated by the rami musculares, branches of the sciatic nerve and by the cranial and/or caudal gluteal nerves (Getty, 1975). Under the current classification they would be considered to have a sciatic neuropathy but this could be incorrect if the damage was only

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to the cranial and/or caudal gluteal nerves. Describing them as a L6-S2 plexus neuropathy is strictly more correct.

The proposed classification is based on clinical presentation from a functional perspective. The ventral branches of the L6-S2 plexus are made up of large numbers of axons. Some of these will form the cranial gluteal nerve, some the caudal gluteal nerve, some the sciatic nerve, some the peroneal and some the tibial nerve. Each of these nerves have multiple branches, which progressively become smaller and innervate specific parts of the limb. When the L6-S2 nerve roots are damaged during a difficult calving, the point of pressure to the ventral nerve roots will vary depending on the precise orientation of the foetus. This will affect which specific axons were damaged and the number of axons damaged, which in turn will affect the clinical presentation of the neuropathy. If the axons forming the branches of the sciatic nerve that innervate the upper thigh musculature are damaged without damaging those that form the branches innervating the lower limb, the clinical presentation will be as described in group one, whereas group two will present if the opposite occurs. Group three cases will present when axons forming the nerve branches supplying both the upper and lower limb are affected.

The amount of pressure and the length of time the pressure was applied to the nerve plexus will also vary from calving paralysis case to case, which will affect the number of axons that were affected and thus the severity of the cases. Those with a more severe grade of damage to the nerves of the distal branches of the L6-S2 nerve plexus would be expected to have more extensive damage. This was the case when comparing cows 3454 and Z66 as the more severe clinical syndrome in cow Z66 was reflected in more damage of her L6-S2 ventral branches.

For the neuropathies affecting the distal branches of the L6-S2 nerve plexus, over many years I have observed the pattern of different sensory loss to the pastern as described by the four grades. The higher value of the grade reflects a higher level of damage. Motor dysfunction causing lack of extension of the digits was observed to be lost before sensory loss to the pastern and sensation to the dorsal pastern was observed to be lost before that to the plantar pastern. Deep pain to the pastern was the last sensation that I observed to be lost. I have therefore hypothesed that the axons that form the branches of the tibial nerve innervating the pastern are more protected in the pelvis than those contributing to the

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peroneal nerve. Moreover, the branches that innervate the deeper structures of the pastern are more protected than those innervating the superficial pastern. More research in this area is needed to further investigate this hypothesis.

The grades describe the functional presentation of the neuropathies irrespective of the actual site of the damage to the nerve. For example, a cow with knuckling of the fetlock and loss of sensation to the dorsal pastern would be coded L6-S2 Grade 0-2, whether it was due to pressure damage to the peroneal nerve where it crossed the lateral tibia from the cow lying in lateral recumbency or due to compression during dystocia of the L6-S2 nerve roots in the pelvis that form the peroneal nerve. The same presentation under the current classification could be described as either sciatic or peroneal nerve damage and without pathology it would be impossible to accurately determine which case was correct.

Post mortem examinations were performed on one cow from each of the three different clinical presentations of L6-S2 nerve plexus injuries. The two cows showing clinical symptoms of dysfunction to the distal branches of the L6-S2 nerve plexus (cows 3454 and Z66) had damage to their L6 and S1 ventral branches whereas cow 2855, that predominately had symptoms of dysfunction to the proximal branches of the L6-S2 nerve plexus, did not have any injury to the L6 ventral branch. The different clinical presentations were reflected in the different sites of injury. During a dystocia the orientation of the obstructed calf would vary from cow to cow, which would affect the precise site of the damage to the nerve roots. This would in turn affect the clinical presentation of the neuropathy, as demonstrated in these three cows.

Cox et al (1975) suggested that the most likely point of compression of the L6/sciatic nerve would be where the L6 ventral branch crossed the acute ridge of the ventral border of the sacrum. This was the site of the most severe damage in cows 3454 and Z66 but it was unaffected in cow 2855. The S1 ventral branch was damaged in all three of these cows, which was not predicted by them.

8.4.2 Prognosis of grades The second part of this study was to determine if the proposed grades could be used to predict a cow’s likely outcome. No specific prognostic information could be found in the literature.

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There were 19 individual grades and as the damage to one hindlimb may be different to that of the other hindlimb, there were an enormous number of different combinations for the presentation of L6-S2 nerve plexus injuries. This made it very difficult to analyse the grading system without having a larger data set so the analysis was only done by the grade of the more severely affected hindlimb. No account was taken of the level of damage to the other hindlimb. The validity of this methodology may need further investigation.

Data of the 19 different grades for the 103 cows were allocated into three groups of severity: mildly affected; moderately affected; and severely affected and correspond to the three prognostic groups of ‘good’, ‘guarded’ and ‘poor’ prognosis, respectively. This was allocated on a statistical and clinical basis: The statistically based allocation only used the recovery data. The mildly affected group was composed of L6-S2 Grades 0-1, 1-0, 2-0 and 2- 1. These grades had day 3, 7 and final recoveries superior to the average of the 103 cows. The moderately affected group was composed of Grades 0-2, 1-1, 1-2 and 2-2 as they had recoveries similar to the average recoveries of the 103 cows. The severely affected group had the remaining grades, namely Grades 0-3, 0-4, 1-3, 1-4, 2-3, 2-4, 3-0, 3-1, 3-2, 3-3 and 3- 4, which had recoveries well below the average.

The Cochran-Armitage test for trend was performed on these three groups to assess the relationship between the level of damage and recovery. There was a strong linear trend of decreased prognosis with increased level of damage when assessed on day 3, day 7 and final recovery for the 103 cows with L6-S2 nerve plexus damage, as shown in Table 8.10.

The grades were also allocated on the basis of ‘clinical judgement’ as there were three factors that could have affected the validity of the recovery statistics: some grades were limited by low numbers of cows or by no cows; the finding from Chapter 5 that once cows were recumbent for more than one day, their chance of recovery was more influenced by any secondary damage that occurred after they became recumbent than by the initial cause of the recumbency; and the finding from Chapter 6 that the level of nursing care was directly related to a recumbent cow’s chance of recovery, and indirectly to the occurrence of clinically important secondary damage.

Clinical observations of the amount of sensory loss and motor function for cows with the different grades were taken into account, particularly for the grades with no representatives or with only small numbers. The four grades of damage to the distal branches of the L6-S2 148

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nerve plexus represent different levels of damage where increased damage corresponds with increasing loss of sensation to the pastern. Proximal Grade 1 and 2 are not linear as they represent mild damage to different branches of the sciatic nerve. There was no significant difference when the recovery of 23 cows that were graded 2-0 or 2-1 and had an increased patellar reflex were compared to the 11 cows graded 2-0 or 2-1 that had normal patellar reflexes (OR 2.9; 95% CI 0.6-13.8; P = 0.18). Proximal Grade 3 is a more severe form of proximal Grade 2. Cows with Grades 2-3, 3-2 and 3-3 were not represented in the data but would be expected to have similar levels of damage to cows of Grades 1-3, 2-4, 3-0 and 3-1, and thus were clinically allocated to the severely affected group.

The analysis of the recovery of the cows that did not suffer clinically important secondary damage was hampered by small numbers as there were only 26 cows in this category. Most of these cows were from the grades in the ‘good’ prognostic group, which strengthens the case for these grades to be in this prognostic group. All of the cows with Grades 3-0, 0-2, 0- 3, 0-4, 1-2, 1-4, 2-4 and 3-1 suffered clinically important secondary damage and thus, were not represented in this table. This finding further strengthened the allocation of these grades to the guarded or poor prognostic groups.

Secondary damage could be predisposed by the type of primary damage that had been inflicted or by sub-optimal nursing. To help consider this aspect the 75 cows that received satisfactory nursing care were analysed separately. The linear trend of increased recovery with decreased level of damage in the three prognostic groups was stronger for this analysis than for the cows nursed under all levels of care. This further validates the prognostic groups by emphasizing the influence that the degree of the primary damage had on recovery without being complicated by the impact of unsatisfactory nursing. The grades allocated to the statistically based poor prognosis group still suffered a high occurrence of clinically important secondary damage when nursed at a satisfactory level with 13/15 (87%) cows affected. This suggested that these grades were prone to secondary damage due to their type of primary damage rather than it occurring due to sub-optimum nursing care.

Grade 1-1 was the only grade that differed between the statistically and clinically based prognostic groups: clinically, it was assessed as a mild form of damage but this was not substantiated statistically with day 3, 7 and final recoveries of 1/11 (9%), 2/11 (18%) and 4/11 (36%), respectively. However, four of these 11 (36%) cows were destroyed after

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Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage suffering secondary hip dislocation, which may have distorted the recovery data for this grade. Cows with Grade 1-1 damage would be expected to have similar levels of damage to Grades 1-0 and 2-1, which are in the mild prognostic group and less damage than Grades 1-2 and 2-2, which are in the moderate prognostic group. My experience over many years is that Grade 1-1 cows have only mild damage and should be in the mild prognostic group.

When the grades were allocated according to ‘clinical judgement’ and the Cochran-Armitage test for trend was repeated there was a similar linear trend of decreased prognosis with increased level of damage as was found in the statistically based groups. This is shown in Table 8.11.

The recommendation from this study is that the three prognostic groups are composed of the grades shown in Table 8.9 under the column ‘based on clinical judgement’.

One of the findings from this part of the study is that the individual grades can be used to estimate the chance of a cow with an L6-S2 nerve plexus injury recovering and the likely time period for this to occur. This can be used by veterinarians when assessing injured cows. Those with mild damage could reasonably be expected to be treated and cared for by the farmers whilst for many cows in the severely affected group immediate euthanasia would be elected. This would improve animal welfare outcomes by concentrating efforts on cows with a reasonable chance of recovery and reducing the number of cows with severe damage and a low chance of recovering being nursed for a period of time before eventually being euthanased. Those cows with moderate levels of damage may be chosen to be treated and cared for if the stock carers are prepared to nurse them under levels of high care for an expected period of time of a week or more. However, due to time pressures, many farmers are only prepared to care for recumbent cows for a short period of time and so may elect to euthanase cows in this group even though they may have recovered if given adequate time. This however, is a good animal welfare outcome.

The grading of L6-S2 nerve plexus damage requires an extensive understanding of functional anatomy and would normally be restricted to veterinarians. However, there was a strong correlation between the weight bearing ability of the weaker hindlimb when first lifted and recovery. This could be used by farmers as a crude measure to judge the severity of the nerve damage. The odds for recovery by day 3 for those cows able to bear at least 75% of their weight on their weaker hindlimb at the first lift was over fourteen times that of those 150

Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage cows not able to. This trend continued for recovery by day 7 and final fate with the odds of recovery being three-fold. However, care needs to be taken to ensure the cow is truly suffering from damage to the L6-S2 nerve plexus, rather than some other condition, and it is limited by certain grades (3-0 and 3-1) that initially may present with satisfactory weight bearing ability but often deteriorate due to their predilection to secondary damage.

Any cow that is to be treated and cared for needs to be managed in ways to reduce the chance of clinically important secondary damage occurring. The odds of recovery by day 7 was shown to be twenty times greater for cows that did not suffer clinically important secondary damage compared to those that did suffer it. Cows that were nursed at an unsatisfactory standard had more than a six-fold increased odds of suffering clinically important secondary damage than those that were nursed satisfactorily. Whilst secondary damage was more likely to occur when cows were nursed at an unsatisfactory level of care, some types of L6-S2 nerve plexus injuries seemed more prone to it. This appeared to be so for Grades 3-0 to 3-4, which had a marked anterior and/or medial hindlimb posture. All of the cows with these grades of damage suffered clinically important secondary damage whether they were nursed satisfactorily or not, as shown in Table 8.4 and Table 8.6. They had an abnormal position when in sternal recumbency due to the affected hindlimb being rotated under the cow, as shown in Figure 8.7. This usually prevented them from sitting on their other leg without lying in lateral recumbency and the net effect was that they seemed particularly prone to secondary pressure damage to the muscles and nerves of the upper thigh region of the affected leg. This was the region innervated by the nerves that were initially damaged. They all deteriorated over several days, rather than improved as other types of L6-S2 nerve plexus injuries often did and only 1/9 (11%) recovered.

It is worth noting that many of the cows in this study were not given an indefinite time period to recover and many were destroyed after only a few days. This may well have affected the findings of this study. The study was undertaken on commercial farms under field conditions rather than in a controlled environment. The ‘intention to treat’ for each cow was not the same.

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Figure 8.7. Cow with L6-S2 proximal grade 3 showing abnormal sitting position

Secondary hip dislocation were a common complication of the cows with L6-S2 nerve plexus damage with 23/103 (22%) cows affected. Many of the dislocated hips were replaced successfully under deep sedation but all relapsed soon afterwards. It seemed that the weakness and incoordination of the hindlimb from the original neuropathy predisposed cows to hip dislocation and when it occurred, made a relapse inevitable. A recommendation from this study is that cows that suffer a secondary hip dislocation following an L6-S2 nerve plexus injury should be euthanased rather than attempting replacement as would normally be the case with a primary hip dislocation.

When L6-S2 nerve plexus injuries were categorized by ‘proximal’, ‘distal’ and ‘proximal and distal’ types, the odds of secondary hip dislocation occurring increased by over eight-fold for the distal group, with 8/13 (62%) affected compared to 15/90 (17%), as shown in Table 8.12. Similarly, the odds of this occurring increased by over four-fold when the cows affected by L6-S2 grades 0-1 and 1-1 were compared to all other groups, with 8/17 (47%) cows affected compared to 15/86 (17%) cows.

Cows with L6-S2 nerve plexus damage have a moderate risk of suffering secondary hip dislocation, which logically would be due to the ataxia and lack of control over the hindlimb,

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often in association with proprioceptive defects. However, it is hard to explain why cows with the distal types and Grades 0-1 and 1-1 were statistically more at risk. A general recommendation for all cows with L6-S2 nerve plexus damage would be to confine them on surfaces with good footing and remove them from other cows to reduce the risk of hip dislocation occurring.

Cows with an L6-S2 nerve injury complicated by obturator nerve damage would be expected to have a higher risk of suffering a secondary dislocated hip due to the abducted tendency of the hindlimb. Cows with obturator nerve complication had nearly a three-fold increased odds of suffering secondary hip dislocation, as shown in Table 8.12, but this was lower odds than those suffering from damage to the distal branches of the L6-S2 nerve plexus. L6-S2 nerve plexus damage complicated by femoral nerve damage or tibial paresis however, did not significantly increase the risk of secondary hip dislocation.

8.5 Conclusions Neuropathies of the axons originating from the ventral branches of the L6-S2 nerve plexus are currently described either as sciatic, peroneal or tibial neuropathies. This can be inaccurate and confusing as there is overlap between sciatic and peroneal neuropathies and the cranial and caudal gluteal nerves are ignored.

Cows with damage to these axons can present with a wide range of syndromes depending on which muscles have lost their motor innervation and which parts of the skin have lost their sensory innervation. The severity of the syndrome will vary from mild to severely affected, depending on the number of axons damaged. This chapter proposes a new way of classifying these neuropathies based on their clinical presentation, differentiated into damage to the proximal, distal or proximal and distal branches of the L6-S2 nerve plexus. The classification incorporates a two digit code to describe the level of damage to the proximal and distal branches.

The second part of this study was to try to determine if the grades used to describe the different presentations of L6-S2 nerve plexus damage could be used to judge the likely prognosis when first attended by the veterinarian. Whilst this is complicated by the occurrence of secondary damage and influenced by the level of nursing care provided to the cows, this study proposes grouping these different types of injury into three categories of

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Chapter 8: Classification and Grading of L6-S2 Nerve Plexus Damage mild, moderate and severe levels of damage with corresponding prognoses of ‘good’, ‘guarded’ and ‘poor’. This can be used when cows are first examined to help decide whether to treat and nurse these affected cows or to elect prompt euthanasia. More research is required to further investigate this grading system.

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Chapter 9. Calving Paralysis

9.1 Introduction Calving paralysis is a syndrome of damage of the pelvic nerves from the passage of an oversized calf through the pelvic canal. It most commonly affects primiparous heifers but can also occur in multiparous cows. It ranges in severity from: a mild paresis; a weakness and knuckling of one or both hind limbs; to a complete inability to rise (Blood et al., 1979).

Over the years, the term ‘obturator paralysis’ has been used synonymously with calving paralysis possibly following experimental bilateral sectioning of the obturator nerves (Vaughan, 1964), which resulted in “a collapse of the hind legs into total abduction”. However obturator nerve damage cannot account for the fetlock flexion that is often associated with calving paralysis (Cox et al., 1975). Cox et al (1975) reproduced the typical presentation of calving paralysis after sectioning the ventral branch of the sixth lumbar (L6) sciatic nerve. The L6 nerve root passes under the acute ventral ridge of the ventral sacrum and they proposed that this would be the likely point of trauma during dystocia (Cox et al., 1975). The presentation of the clinical signs of calving paralysis can vary considerably depending upon the extent of the nerve damage to the nerves within the pelvic canal (Cox, 1988). Divers (2004), Fenwick (1969), Galabinov (1966) and Parkinson et al (2010) describe sciatic involvement in calving paralysis and Divers (2004) and Galabinov (1966) state that it is the most commonly affected nerve. Yet despite this, the obturator nerve is still commonly thought of as the main cause of calving paralysis (Parkinson et al., 2010).

The anatomy, function and dysfunction of the major nerves of the bovine hindlimb are described:

The cranial gluteal nerve arises primarily from ventral branches of L6 and first sacral (S1) nerves. It innervates the: tensor fascia lata, which flexes the hip joint and extends the stifle; the gluteus medius, which extends the hip, abducts the limb and rotates the femur; and the gluteus profundus, which abducts the thigh and rotates it medially (Getty, 1975).

The caudal gluteal nerve arises essentially from the ventral branches of S1 and S2. It innervates: the gluteobiceps muscle, which extends the hip, stifle and hock and flexes the stifle and abducts the limb; and the gluteus medius muscle, which extends the hip, abducts the limb and rotates the femur (Getty, 1975).

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No references to damage to the cranial and caudal gluteal muscles could be found in the literature but it would be expected to present as the hindlimb in an anterior and/or medial posture due to lack of extension and abduction by the gluteobiceps and gluteus medius muscles. These muscles however, are also innervated by branches of the sciatic nerve.

The sciatic nerve originates mainly from the last lumbar and first two sacral components of the lumbosacral trunk (Getty, 1975). The L6 origin of the sciatic nerve courses closely to the ventral border of the wing of the sacrum and is tightly opposed to its acute ridge (Cox et al., 1975). It joins with the S1 and S2 ventral branches in the dorsal pelvis to form the sciatic nerve. It releases several branches, the ramus muscularis and rami musculares, which innervate the muscles of the pelvis and upper thigh (gluteus medius, gluteobiceps, semitendinosus, semimembranosus, adductor, quadratus femoris and gemelli) (Getty, 1975). These muscles serve as extensors of the hip and hock and flexors of the stifle, and have a role in both abducting and adducting the limb, and also extending the stifle (Getty, 1975).

The sciatic nerve bifurcates into the peroneal and tibial nerves at the mid-thigh region. The peroneal nerve courses anteriorly and laterally over the stifle, and passes behind the residual head of the fibula under the lateral condyle of the tibia. It innervates the muscles of the anterior aspect of the lower limb below the stifle. These muscles flex the hock and extend the digits (Getty, 1975). The peroneal nerve divides into the superficial and deep common peroneal nerves, which further divide into a number of branches suppling sensory and motor function to the dorsal, dorso-lateral and dorso-medial aspects of the digits (Getty, 1975).

The tibial nerve passes between the two heads of the gastrocnemius and innervates the muscles that flex the stifle, extend the hock and flex the digits (Getty, 1975). The tibial nerve divides into the medial and lateral plantar nerves at the level of the hock and further divides into progressively smaller nerves, innervating the plantar, planto-lateral and planto-medial aspects of the digits (Getty, 1975). All of the sensory function to the hindlimb below the fetlock is supplied by the peroneal and tibial nerves (Hall, 1971).

Chapter 9: Calving Paralysis ground. The only skin sensation present on the hind limb was at the medial thigh, which is innervated by the saphenous nerve, a branch of the femoral nerve (Vaughan, 1964). Damage to the sciatic nerve will result in a weakness to the hindlimb and the fetlock will be knuckled over (Constable, 2004, Parkinson et al., 2010). The patellar reflex may be normal or increased due to lack of tone in the hamstring group of muscles, which oppose the contraction of the quadriceps muscles (Constable, 2004).

When the peroneal nerve was experimentally sectioned at the level of the lateral head of the gastrocnemius hyperextension of the hock and hyperflexion of the fetlock resulted with the anterior pastern resting on the ground. Full weight could be taken by the limb when the hoof was manually placed in the normal position but it immediately reverted to the abnormal position as soon as the first stride was taken (Vaughan, 1964). Sensation was reduced or lost to the cranial aspect of the pastern (Keown, 1956, Parkinson et al., 2010). The peroneal nerve is susceptible to damage where it crosses the head of the fibula on the anterior lateral stifle, as it lies superficially in this position (Keown, 1956, Parkinson et al., 2010, Vaughan, 1964) but it can also be damaged during a difficult calving (Constable, 2004, Vaughan, 1964).

Sectioning of the tibial nerve between the two heads of the gastrocnemius resulted in the calves standing with hyperflexion of the hock and a forward knuckling of the fetlock. The sole of the hooves remained in contact with the ground (Vaughan, 1964) due to paralysis of the extensors of the hock and flexors of the digits (Parkinson et al., 2010). The gastrocnemius muscles atrophied in the weeks after the tibial nerve was sectioned (Vaughan, 1964).

Cows with damage to the sciatic nerve show a variety of dysfunctions, as described above, and may include:

• Anterior and/or medial posture of hindlimb when in the standing position

• Increased patellar reflex

• Weakness of the hindlimb involving the muscles innervated by these nerves

• Knuckling of the pastern

• Loss of sensation to the skin of the dorsal and/or plantar aspects of the pastern

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• Hyperflexion of the hock and fetlock but with the sole of the hoof placed normally (tibial paresis)

The femoral nerve in cattle forms from the ventral branch of the fifth lumbar nerve, with contributions from the fourth and sixth lumbar nerves. It innervates the quadriceps femoris, which is a strong extensor of the stifle joint and flexor of the hip. It gives branches to the psoas and iliacus muscles, which flex the hip and rotate the thigh; and the sartorius muscle, which flexes the hip and adducts the limb. The saphenous nerve, a branch of the femoral nerve, continues along the medial aspect of the thigh providing sensory function to the fascia and skin of the medial aspect of the leg to the level immediately distal to the tarsus (Getty, 1975). I diagnosed femoral nerve damage when the cow presented with a depressed or absent patellar reflex and a caudal tendency of the hindlimbs when she tried to stand.

The obturator nerve forms from the continuation of the ventral branch of the fifth lumbar nerve, from a small branch from the ventral branch of the sixth lumbar and usually from one or two slender branches of the fourth lumbar nerve. It courses caudo-ventrally along the ilium to the cranial end of the obturator foramen. It splits into several branches to innervate the adductor, pectineus, gracilis, quadratus femoris, obturatorius externus and internus muscles (Getty, 1975). The obturator nerve provides the main adductor function to the hind limb but the sciatic nerve also has some adductor function (Cox and Martin, 1975).

Experimental bilateral sectioning of the obturator nerve prevented only one of 11 adult cattle from rising without assistance immediately after sectioning and this cow was subsequently found to have ruptured stifle ligaments. Eight of the ten cattle had ataxia on a slippery surface and their legs spread laterally but their gait was normal at the walk. After falling the cows were always able to stand again after obtaining good footing (Cox and Martin, 1975).

I diagnosed obturator nerve damage when the cow showed an abducted hindlimb in the absence of other damage which could account for it, such as a hip dislocation or torn adductor muscles.

The aims of this study were to describe which nerve(s) were damaged in calving paralysis cases in field situations.

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9.2 Materials and Methods Field studies of recumbent dairy cows were conducted in South Gippsland during two three- month periods in the winter calving months of 2011 and 2012. Recumbent cows were included in the study if they were bright, alert and responsive; and there was adequate history for them to be assessed properly. From this group of cows a sub-group of those that were recumbent from calving paralysis was formed. They were not required to be recumbent for more than one day to be included in this section.

Cows were initially attended by a veterinarian as soon as possible after the recumbency, ideally on the first day, and revisited once or twice weekly, when possible. Thorough medical and musculo-skeletal clinical examinations were performed on each cow at each visit. The nerve function assessment was by:

• Flexor-withdrawal reflex, patellar reflex and muscle tone assessment in the recumbent position

o The ‘superficial’ flexor-withdrawal reflex was assessed by provoking the skin of the dorsal and plantar pastern with a hypodermic needle or an electric cattle prodder to induce withdrawal of the leg from the noxious stimulus

o The ‘deep’ flexor-withdrawal reflex was assessed by squeezing the inter- digital area with hoof testers to induce withdrawal of the leg from the noxious stimulus

• Flexor-withdrawal reflexes and muscle tone assessment were repeated in the elevated position

The anatomy, function and dysfunction of the hindlimb nerves, as listed in the introduction, were used when determining the particular neuropathy for each cow.

9.2.1 Statistical analysis For this section, the only statistical analysis performed was for investigating the association between the different neural presentations of calving paralysis and the occurrence of

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secondary hip dislocation. A case cow was defined as suffering secondary hip dislocation and a control cow as one that did not suffer one. Odds ratio (OR), 95% confidence interval (CI) and Wald P value were used to measure the strength of association between risk factors and case/control status. StatXact 10 (Cytel, Cambridge, MA) and WinPepi 11.48 (Abramson, 2011) software were used for the analyses. Two-sided P values < 0.05 were regarded as statistically significant.

9.3 Results One hundred and four cases of calving paralysis were investigated on 60 dairy farms over two years. The sciatic nerve was the most commonly affected nerve, which occurred in 100/104 (96%) cows, either by itself or in various combinations with the obturator and femoral nerves. Pelvic fracture was observed in 3/104 (3%) cows. The different clinical presentations of the calving paralysis cases are shown in Table 9.1.

Table 9.1. Clinical presentation of 104 cows recumbent with calving paralysis Predominant Other nerves or structures Sub total major nerve affected affected n % n % Sciatic No other structures damaged 64 62 Obturator 21 20 Femoral 4 4 Obturator and femoral 7 7 Pelvic fracture 2 2 Total sciatic 98 94 Obturator No other structures damaged 0 0 Ruptured stifle 1 1 Total obturator 1 1 Femoral No other structures damaged 1 1 Pelvic fracture 1 1 Sciatic 2 2 Obturator 1 1 Total femoral 5 5 Total 104 100

The sciatic nerve and its branches were involved in 100/104 (96%) cows. Damage to the sciatic nerve presented in a variety of clinical ways depending on which branches were damaged and on the extent of the damage to them. Many of these cows also had

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concurrent obturator or femoral nerve damage. Two cows with sciatic nerve damage showed mainly femoral nerve damage, thus 98/104 (94%) cows presented with sciatic nerve damage as the main neuropathy.

Obturator nerve damage was recorded in 30/104 (29%) cows. No cows recumbent with calving paralysis suffered solely from obturator nerve damage. Obturator nerve damage was the only nerve damaged in one cow but she also had ruptured stifle ligaments of one hind limb, which was the reason for her recumbency, not the obturator neuropathy. Several cows were observed to have obturator paresis where they were able to walk with splayed legs, without signs of other nerve damage but as they were not recumbent they were not part of the study.

Femoral nerve damage was recorded in 16/104 (15%) cows. It occurred as an incidental finding in combination with sciatic neuropathies in 11 cows and in combination with pelvic fracture in one cow. However, four (4%) cows presented predominately with femoral nerve dysfunction. It occurred with concurrent sciatic nerve damage in two (2%) cows and with obturator damage in one (1%) cow but it was the only nerve affected in one (1%) cow.

Secondary hip dislocation was a common finding affecting 23/104 (22%) cows. Table 9.2 shows the occurrence of secondary hip dislocation when the neuropathy involved either obturator or femoral nerve damage compared to its occurrence when the neuropathy did not involve damage to the obturator or femoral nerve.

Table 9.2. Susceptibility of cows to secondary hip dislocation if the obturator or femoral nerve was part of the neuropathy in 104 cows recumbent with calving paralysis Nerves affected from calving Secondary hip OR 95% CI P paralysis dislocation n n % All types with obturator 30 11 37 3.0 1.1-7.9 0.026 All types without obturator 74 12 16 1 [REF] All types with femoral nerve 16 2 13 0.5 0.1-2.2 0.32 All types without femoral nerve 88 21 24 1 [REF] Total 104 23 22

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9.4 Discussion The study found that the sciatic nerve was the most commonly affected nerve damaged in cows with calving paralysis. This was consistent with the findings of some authors (Cox and Breazile, 1973, Divers, 2004, Fenwick, 1972, Galabinov, 1966) but at odds with other authors (Parkinson et al., 2010, Vaughan, 1964) and with the general misconception by veterinarians that the obturator nerve is the most commonly affected nerve. Sciatic nerve damage was involved in 100/104 (96%) of cases of calving paralysis either by itself or in combination with other nerve damage. It was the only nerve affected in 66/104 (64%) cows, two of which also had a pelvic fracture. It was affected in combination with obturator nerve damage in 21/104 (20%) cows and in combination with femoral nerve damage in 6/104 (6%) cows although two of these six cows presented predominately with femoral nerve damage. The combination of sciatic, obturator and femoral nerve damage was recorded in 7/104 (7%) cows.

No recumbent cows were solely affected with obturator nerve damage. Some cows with calving paralysis showed abducted hindlimb(s), consistent with obturator damage but all had other damage, including one cow with stifle ligament rupture, which was the cause of their paralysis. Concurrent obturator nerve damage occurred in 30/104 (29%) cows with calving paralysis. This finding contrasts with some authors in the literature that state or imply that the obturator nerve is the main nerve affected with calving paralysis (Parkinson et al., 2010, Vaughan, 1964) and agrees with other authors that state that the sciatic nerve is the most commonly affected nerve (Constable, 2004, Cox et al., 1975, Divers, 2004, Galabinov, 1966).

Femoral nerve injury was diagnosed in 16/104 (15%) cows with calving paralysis. This has not been recorded in the literature previously. The femoral nerve originates from the fourth and fifth lumbar nerve (Getty, 1975) and as the nerve does not pass through the pelvic canal it has not been considered to be associated with calving paralysis. However, if an oversized calf is wedged in the pelvic canal there is also a risk of damage to the structures of the lower lumbar spine, including the femoral nerve roots. Two cows when first found by the farmers with the calf lodged in the pelvic canal were recumbent with their hindlimbs retracted caudally. One had pushed herself into a corner of the shed and the other was in a drain. It is probable that the situations in which they were found caused the hindlimbs to be in the

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caudal position, which caused rotation of the pelvis and subjected the femoral lumbar nerve roots to pressure damage.

Femoral nerve damage was diagnosed on the basis of absent patellar reflexes and a caudal tendency of the hindlimbs when attempting to stand. It seemed to be an incidental finding in 12 (12%) cows, one of which also had pelvic fracture. However, four cows showed clinical signs predominately of femoral nerve dysfunction. This study records a new finding that femoral nerve damage can be part of the calving paralysis syndrome.

The data showed that secondary hip dislocation occurred in 23/104 (22%) of calving paralysis cows, none of which survived despite many of them being successfully replaced under deep sedation. It seemed that primary nerve damage to the hindlimb made it inevitable that the dislocated hip would reoccur after being replaced under sedation and a further finding from this study is that cows with a secondary dislocated hip following nerve damage to the hindlimb should be euthanased promptly rather than attempting to replace the hip, as would be normal practice for a primary dislocated hip. If obturator nerve damage was part of the calving paralysis syndrome the odds of secondary dislocated hip occurring increased three-fold. The study recommends that cows with obturator damage are managed in ways that will reduce the risk of secondary hip dislocation by measures, such as confinement in small pens, avoiding access to areas with slippery footings and the use of hobbles. There was no significant increase in risk of secondary dislocated hip from concurrent femoral nerve damage, as shown in Table 9.2.

9.5 Conclusions Findings from the study showed that the sciatic nerve was overwhelmingly the major nerve affected in cows with calving paralysis. The other major nerves of the lumbo-sacral plexus can be affected and can occur in any combination with each other. No cow with damage solely to the obturator nerve was observed to be paralysed. The femoral nerve can be affected in calving paralysis cows, often as an incidental finding but it can be the dominant or only nerve affected.

Calving paralysis is an excellent term to describe cows with hindlimb nerve damage following dystocia but this study proposes that it should be thought of as a paralysis of the nerves of the lumbo-sacral plexus.

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Chapter 10. Conclusions Downer cows, defined as bright and alert cows that have been recumbent for more than one day (Cox, 1981) are a common problem in the Australian dairy industry (Watson and Watson, 2014) as they are in other dairy areas around the world (Van Metre, 2001).

This study researched the management of downer cows under field conditions in South Gippsland, Victoria, Australia. It investigated a variety of aspects including their clinical examination, diagnosis and prognosis, predisposition to secondary damage and nursing care or euthanasia.

10.1 Summary of Chapter Findings

10.1.1 Chapter 4: Musculo-skeletal examination of the recumbent cow When recumbent cows are first found by farmers it is important that the cause of the recumbency is correctly identified so that they are managed correctly. If the farmer is unsure of the cause, veterinary expertise should be sort. Even when farmers know the primary cause of the recumbency, veterinarians should still be involved in case management as many cows may have developed secondary damage that farmers can be unaware of, leading to their inappropriate management.

It is vital that when veterinarians examine recumbent cows they do so thoroughly, to determine both the primary cause of the recumbency and to determine whether any secondary damage has occurred. Musculo-skeletal damage, either primary or secondary, is a common type of damage in recumbent cows, inferring that examination must include a complete musculo-skeletal assessment. This can be more difficult in cows than in small animals but the same principles apply. If a thorough musculo-skeletal examination, including patellar reflex testing and lifting of the animal to assess posture and postural responses is not conducted, the study has shown that approximately one-third of the different types of secondary damage could be missed. This would lead to an incorrect diagnosis and inappropriate management for many cows.

10.1.2 Chapter 5: The importance of secondary damage in downer cows The successful recovery of the 218 downer cows in the study was 24% (52 cows) by day 7 with a final recovery of 32% (69 cows). This compares with similar results from a recent survey of the Australian dairy industry (Watson and Watson, 2014) but lower than figures

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Chapter 10: Conclusions published in the literature from the British dairy industry where approximately one half of the cows recovered within four to seven days (Andrews, 1983, Chamberlain, 1987).

The primary cause of the recumbency was categorised into one of five groups: post- parturient hypocalcaemia (milk fever); protein-energy deficiency; calving paralysis; back injury; or other. It was shown that once the cows in the study had been recumbent for more than one day there was no difference in recovery between the five primary causative groups. Clinically important secondary damage occurred in 173 (79%) cows with the occurrence of clinically important secondary damage shown to decrease the day 7 odds of recovery by nearly eight-fold compared to cows that did not suffer any secondary damage. It was found that for the majority of the 149 (68%) cows that did not recover, the secondary damage was more important in determining their fate than the initial cause of their recumbency.

10.1.3 Chapter 6: High quality care improves outcome in recumbent cows The conditions under which the recumbent cows were cared for were recorded and analysed. The large range of different factors made it impossible to assess them individually so four categories of nursing quality were developed, ranging from excellent to very poor. The nursing grade was assigned at the completion of the recumbency on the basis of the criteria but without consideration of the outcome. There was a strong linear trend of increased day 7 recovery with increased level of overall nursing care (P = 0.001). There was a strong association between the occurrence of clinically important secondary damage and a decreasing overall level of nursing care (P < 0.001). The study concluded that an increased level of nursing care directly increased recovery by giving cows a higher chance of recovery from the primary cause of their recumbency, and indirectly increased recovery from a decreased chance of suffering clinically important secondary damage, with an improved chance of recovery from such damage, if it occurred.

The management of recumbent cows is an important animal welfare issue for the dairy industry as it is a potential area of focus of animal welfare groups. The level of nursing care in the study area was found to generally poor with 102/218 (47%) cows considered to have been nursed under ‘unsatisfactory’ conditions when they were first attended by the veterinarian and 67/218 (31%) cows nursed ‘unsatisfactorily’ overall. High quality nursing had a significantly positive influence on the recovery of recumbent cows as 65/151 (43%)

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Chapter 10: Conclusions

cows that were nursed under ‘satisfactory’ levels overall eventually recovered compared to 4/67 (6%) cows nursed ‘unsatisfactorily’ overall. These factors highlight the need for improved management of recumbent cows in the Australian dairy industry. This can be achieved through better education of farmers, veterinarians and industry advisors in relation to nursing care.

One recommendation from this study is that if downer cows cannot be nursed under high levels of care, for any reason, they should be promptly euthanased to avoid unnecessary suffering as their chance of recovery is very low.

10.1.4 Chapter 7: Management of bilateral femoral nerve injuries in cows Femoral neuropathies are considered in the literature to be uncommon and most likely to present in heavily muscled calves as a result of a difficult birth. It states that femoral nerve damage “may occur” when recumbent cattle struggle to rise by over-stretching the lumbar roots of the femoral nerve. Femoral nerve damage was found to have occurred in 87/218 (40%) cows so this study proposes that bilateral femoral nerve damage in cattle should be described as “occurring commonly”, both as a primary injury and as secondary damage when recumbent cattle struggle to rise.

I observed femoral neuropathies in four distinct clinical presentations and the study proposes that they are described by a four-tiered grading system. Recovery data was analysed to show that the prognosis for femoral neuropathies decreased as the grade of severity increased. I consider that the management of each grade is different and the ideal nursing requirements for the grades were proposed as part of this study. Recovery of each grade based on compliance to the specified nursing requirements was analysed and a trend of increased recovery with increased compliance was noted over the four combined grades and for the Grade 1 femoral neuropathies in particular. The trend was not statistically significant for Grades 2 - 4 but this may have been due to the limited numbers of cows studied. It was found that the prognosis for cows with a femoral neuropathy was determined by the grade of damage and by compliance to the nursing requirements for its particular grade. It is hoped that the study may stimulate future research in this area to further validate the proposed classification and management of femoral neuropathies.

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Chapter 10: Conclusions

10.1.5 Chapter 8: Classification and grading of L6-S2 nerve plexus damage Neuropathies of the sciatic nerve and its branches are described in the literature but information about assessing the degree of damage is not recorded. The study investigated these syndromes and concluded that current classifications could be misleading, confusing those responsible for managing downer cows. A new classification was proposed where these neuropathies are described as neuropathies of the proximal and/or distal branches of the L6-S2 nerve plexus. This was based on clinical presentation from a functional perspective. It includes neuropathies of the cranial and caudal gluteal nerves, the sciatic nerve and its branches, the peroneal and tibial nerves. It does not include the syndrome ‘tibial paresis’, a distinct neuropathy, which remains as a separate entity. Three grades of damage to the proximal branches and four grades to the distal branches of the L6-S2 plexus were identified. The neuropathies were described with a two-digit code, ‘x-y’, where ‘x’ is the grade of the proximal branch and ‘y’ is the grade of the distal branch. Recovery data from 103 cows with neuropathies of the L6-S2 nerve plexus were analysed and the 19 different grades allocated to three groups of severity. It was proposed that these grades could be used to better estimate the likely chance of recovery for cows suffering from such neuropathies.

It is hoped that the classification system will allow cows with these neuropathies to be more readily recognised and the grades used to allow a more accurate assessment of their chance of recovery. Further work is required to validate the prognostic ability of these grades.

10.1.6 Chapter 9: Calving paralysis Cows with calving paralysis were examined and the types of neuropathies leading to the condition were recorded. The sciatic nerve was the major nerve damaged in these cases with a wide variety of different clinical presentations. Damage to the obturator and femoral nerves were also recorded but usually found in combination with sciatic nerve damage. Obturator nerve without other damage was not observed to cause recumbency in any cow, which is at odds with many reports in the literature that describe calving paralysis as “obturator nerve paralysis” (Parkinson et al., 2010, Vaughan, 1964). Post mortem examinations on a selected number of cows with calving paralysis showed that the variations in clinical presentation seemed to be associated with variations in the site of damage to the L6-S2 nerve plexus. Cox (1975) predicted that the likely site of damage was to

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Chapter 10: Conclusions the L6 nerve root where it passed under the ventral ridge of the wing of the sacrum. This was apparent in some cases in the current study but damage to the S1 and S2 nerve roots was also noted. A number of cows with damage to the L6-S2 plexus only had injury to the S1 and S2 nerve roots and did not have damage to the L6 root. Femoral nerve damage was recorded in a number of cows with calving paralysis in association with sciatic nerve injury but it was found to be the main neuropathy in four cows. Understanding that femoral nerve injury can be a part of the calving paralysis syndrome is a new finding in the literature. This study therefore proposes that calving paralysis should be thought of as a paralysis of the lumbo-sacral nerve plexus.

10.2 Future Studies Classifying sciatic and peroneal nerve injuries as injuries to the proximal and/or distal branches of the L6-S2 plexus and grading them with a two-digit code are new concepts proposed by this study. Using these grades to estimate the level of damage that has been sustained and thus, to predict the likely chance of recovery is also novel. Further research to investigate these findings is required.

The classification of femoral neuropathies into four grades to describe the clinical presentation and severity of the neuropathy are new concepts that also require further validation. The study proposed an ideal level of management for cows with each grade of damage to the femoral nerve and found that recovery was related to compliance to the recommendations. Further work is required to fully validate these findings particularly as there were low numbers of cows in the study for some of the grades.

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Chapter 10: Conclusions

10.3 Final Conclusions for Research Questions The thesis addressed six research questions and reached the following conclusions:

1. How important are the secondary effects of recumbency on the outcome of the cow, compared to the importance of the primary condition?

a. Once cows were recumbent for more than one day, secondary damage occurred commonly

b. Secondary damage was more important in influencing the outcome than the primary cause of the recumbency in most downer cows

2. Do nursing factors influence the occurrence of secondary damage in recumbent cows and influence recovery?

a. Increased level of nursing care was associated with increased recovery

b. Decreased level of nursing care was associated with increased occurrence of clinically important secondary damage

c. Increased occurrence of clinically important secondary damage was associated with decreased recovery

d. The quality of the nursing care of recumbent cows was often sub-optimal in the study area

e. Nursing guidelines for the optimum management of recumbent cows in southern Australian were proposed

f. The study recommends that if downer cows cannot be nursed with a high level of care, no matter the cause of their recumbency, they should be euthanased promptly to avoid unnecessary suffering

3. What is ‘best practice’ for musculo-skeletal examination of recumbent cows?

a. Techniques for improving the musculo-skeletal examination of recumbent cows were established

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Chapter 10: Conclusions

b. Performing a complete musculo-skeletal examination will maximise the chance of accurately diagnosing many of the causes of recumbency and enable the severity of some conditions to be assessed

c. Cows recumbent from severe conditions should be euthanased promptly to avoid unnecessary suffering

4. In cases of femoral nerve injury, can a grading system be developed to describe the different clinical presentations and predict the chance of recovery?

a. A new classification system for femoral nerve injuries was proposed to describe their clinical presentation, assess the severity of damage and predict their likely prognostic outcomes

b. Guidelines for the optimum management of the four individual grades of femoral neuropathy were proposed

5. In cases of sciatic nerve injures, can a grading system be developed to describe the different clinical presentations and predict the chance of recovery?

a. A new classification system for sciatic nerve injuries was proposed to describe their clinical presentation, assess the severity of damage and predict their likely prognostic outcomes

6. What nerve/s are damaged in cases of calving paralysis and where is the site/s of the damage?

a. There were a wide range of neuropathies associated with calving paralysis

b. The sciatic nerve was the most commonly affected nerve

c. No cows were recumbent solely from obturator nerve damage

d. The femoral nerve was damaged in some cows with calving paralysis, usually concurrent with other nerve damage but was also found to be the main neuropathy in several cases of calving paralysis

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Chapter 10: Conclusions

10.4 Final Statement The overriding theme of this thesis has been to improve the understanding of the management of recumbent cows. Focus has been directed at improving their musculo- skeletal examination and assessment to enable more accurate diagnoses to be reached and prognosis to be estimated. Sciatic neuropathies were re-classified as neuropathies of the proximal and/or distal branches of the L6-S2 nerve plexus. L6-S2 nerve plexus and femoral neuropathies were graded based on their clinical presentation, level of damage and likely recovery. The importance of secondary damage in recumbent cows was highlighted along with its association with the level of nursing care. Nursing quality was shown to be highly influential in the recovery of recumbent cows.

A better understanding of the management of downer cows will lead to improved welfare outcomes by both an increased chance of recovery for those cows that are nursed and by the prompt euthanasia for those cows with poor chance of recovery or which are unable to be cared for at a high standard.

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Bibliography

Chapter 11. Bibliography ABRAMSON, J. H. 2011. WINPEPI updated: computer programs for epidmiologists, and their teaching potential. Epidemiologic perspectives and innovations, 8:1 ANDERSON, P. H., BERRETT, S. & PATTERSON, D. S. P. 1976. The significance of elevated plasma creatine phosphkinase activity in muscle disease of cattle. J Comp Pathol, 86, 531-8. ANDREWS, A. H. 1983. Prognosis in the downer cow syndrome. The Bovine Practitioner, 18, 41-43. ANDREWS, A. H. 1986. The downer cow. In Practice, 18, 187-189. ANDREWS, A. H. 1992. The downer cow. The Veterinary annual, 32, 242-249. ARMITAGE, P. 1955. Tests for linear trends in proportions and frequencies. Biometrics, 11, 375-386. BELLOLI, A., ARRIGONI, S. & GUARNERI, D. 1996. Approccio clinico della "sindrome della vacca a terra". Large Animal Review, 2, 19-24. BLOOD, D. C., HENDERSON, J. A. & RADOSTITS, O. M. (eds.) 1979. Veterinary Medicine A textbook of the diseases of cattle, sheep, pigs and horses., London: Bailliere Tindall. BURTON A.J., N. D. V., OLLIVET T.L., DIVERS T.J. 2009. Prognostic indicators for nonambulatory cattle treated by use of a flotation tank system in a referral hospital: 51 cases (1997-2008). J Am Vet Med Assoc. , 234, 1177-82. CHAMBERLAIN, A. T. 1987. The management and prevention of the downer cow syndrome. Proceedings of the British Cattle Veterinary Association, 20-30. CHESTERTON 2011. The cow bath. Proceedings of the Society of Dairy Cattle Veterinarians of the NZVA, 7.7.1 - 4. CLARK, R. G., HENDERSON, H. V., HOGGARD, G. K., ELLISON, R. S. & YOUNG, B. J. 1987. The ability of biochemical and haematological tests to predict recovery in periparturient recumbent cows. New Zeal Vet J, 35, 126-33. CLARK, R. G., HOGGARD, G.K., AND MOORE, M. 1984. The use of muscle enzyme tests creatine phosphokinase and aspartate transferase as prognostic tests in downer cows Surveillance 11, 3 - 5. COCHRAN, W. G. 1954. Some methods for strengthening the common chi-squared tests. Biometrics, 10, 417-451. CONSTABLE, P. D. (ed.) 2004. Veterinary clinics of North America Food animal practice ruminant neurological diseases. Chapter 1 Clinical examination of the ruminant nervous system, Philadelphia: Saunders. CORREA, M. T., ERB, H. N. & SCARLETT, J. M. 1993. Risk factors for downer cow syndrome. J Dairy Sci, 76, 3460-3. COX, V. S. 1981. Understanding the downer cow syndrome. Continuing Education Article, 3, 472-8. COX, V. S. 1982. Pathogenesis of the downer cow syndrome. Vet Rec, 111, 76-9. COX, V. S. 1988. Nonsystemic causes of the downer cow syndrome. Vet Clin North Am Food Anim Pract, 4, 413-33. COX, V. S. & BREAZILE, J. E. 1973. Experimental bovine obturator paralysis. Vet Rec, 109-110. COX, V. S., BREAZILE, J. E. & HOOVER, T. R. 1975. Surgical and anatomic study of calving paralysis. Am J Vet Res, 36, 427-30. COX, V. S. & MARTIN, C. E. 1975. Peroneal nerve paralysis in a heifer. J Am Vet Med Assoc, 167, 142- 4. COX, V. S., MCGRATH, C. J. & JORGENSEN, S. E. 1982. The role of pressure damage in pathogenesis of the downer cow syndrome. Am J Vet Res, 43, 26-31. DAIRY AUSTRALIA. 2015. DE LAHUNTA, A. & GLASS, E. (eds.) 2009. Veterinary neuroanatomy and clinical neurology, St Louis, Missouri: Saunders Elsevier. DIVERS, T. J. 2004. Acquired spinal cord and peripheral nerve disease. Vet Clin North Am Food Anim Pract, 20, 231-42, v-vi. FENWICK, D. C. 1969. The downer cow syndrome. Aust Vet J, 45, 184-8. FENWICK, D. C. 1972. Calving paralysis. Victorian Veterinary Proceedings, 30, 45.

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FLAGSTAD, T., NIELSON, K. & SIMESON, M. G. 1970. Taumatiske muskellidelser ved parese hos Kvag. Dansk Drylaegeforening Medlemsblad, 53, 363. FLEISS, J. L., LEVIN, B. & PAIK, M. C. (eds.) 2003. Statistical methods for rates and proportions, New Jersey: John Wiley and Sons, Inc. FORBES, E., KNIGHT, A. & TURNER, G. W. 1986. The Australian Oxford MiniDictionary. In: FORBES, E., KNIGHT, A. & TURNER, G. W. (eds.) The Australian Oxford MiniDictionary. Melbourne: Oxford University Press. GALABINOV, G. 1966. [On the etiology, pathogenesis and clinical aspects of post-partum lying of cows]. Monatshefte für Veterinärmedizin, 21, 601. GALABINOV, G. 1972. [Clinical and pathomorphological changes in bovine post-parturient paraplegia]. Wiener tierärztliche Monatsschrift, 59, 369. GARDNER, I. A. & GREINER, M. 2006. Receiver-operating characteristic curves and likelihood ratios: Improvements over traditional methods for the evaluation and application of veterinary clinical pathology tests Vet Clin Pathol, 35, 8 - 17. GETTY, R. (ed.) 1975. Sisson and Grossman’s the anatomy of domestic animals, Philadelphia: Saunders HALL, L. W. (ed.) 1971. Wright’s veterinary anaesthesia and analgesia, London: Baillere Tindall. HARWOOD, J. P. P. 2003. Tackling the problem of the downer cow: cause, diagnosis and prognosis. Cattle Practice, 11, 89-92. HUXLEY, J. N. 2006. Assesment and management of the recumbent cow. In Practice, 28, 176-184. HUXLEY, J. N., ARCHER, S.C., BIGGS, A.M., BRADLEY, A.J., BREEN, J.E., GREEN, M.J.,, HIGGINS, H. M., HUDSON, C.D., HUSBAND, J.A., MAY, W., READER, J.D., STATHAM, J.M.E., & THORNE, M. H., WAPENAAR, W. 2010. An Expert Review of the Diagnosis, Prognosis and Treatment of Recumbency in Adult Cattle. Cattle Practice, 18, 53 - 60. JONSSON, G. & PEHRSON, B. 1969. Studies on the downer syndrome in dairy cows. Zentralbl Veterinarmed, 16, 757. KEOWN, G. H. 1956. Peroneal nerve damage. Canadian Journal of Comparative Medicine, 20, 445-8. KRONFELD, D. S. 1970. The "downer" problem. In: GIBBONS, W. J., CATCOTT, E. J. & SMITHCORS, J. F. (eds.) Bovine Medicine & Surgery and Herd Health Management. First ed. Wheaton, Illinois: American Veterinary Publications, Inc. PARKINSON, T. J., VERMUNT, J. J. & MALMO, J. (eds.) 2010. Diseases of cattle in Australasia, Wellington: VetLearn. PAULSEN, D. B., NOORDSY, J. L. & LEIPOLD, H. W. 1981. Femoral nerve paralysis in cattle. Bovine Practice, 2, 14-22. PLATT, S. & GAROSI, L. (eds.) 2012. Small animal neurological emergencies, London: Manson Publishings Ltd. RADOSTITS, O. M., GAY, C. C., HINCHCLIFF, K. W. & CONSTABLE, P. D. (eds.) 2010. Veterinary Medicine: A Textbook of the Diseases of Cattle, Sheep, Pigs and Horses, Edinburgh: Saunders. SHPIGEL, N. Y., AVIDAR, Y. & BOGIN, E. 2003. Value of measurements of the serum activities of creatine phosphokinase, aspartate aminotransferase and lactate dehydrogenase for predicting whether recumbent dairy cows will recover. Vet Rec, 152, 773-6. SMITH-MAXIE, L. 1997. Diseases of the Nervous System. In: GREENOUGH, P. R. (ed.) Lameness in cattle. 3rd ed. Pennyslvania: W.B. Saunders. VALBERG, S. J., HODGSON, D. R. & (eds.) 1996. Large Animal Internal Medicine, St Louis: Mosby. VAN METRE, D. C. 2001. Downer cows – diagnosis and assessment ACV Conference Proceedings, 14- 21. VAUGHAN, L. C. 1964. Peripheral nerve injuries: An experimental study in cattle. Vet Rec, 76, 1293- 1301. WATSON, P. & WATSON, D. 2012. Dairy Australia: Animal Husbandry Survey. Dairy Australia. WATSON, P. & WATSON, D. 2014. Dairy Australia Animal husbandry survey main report.

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Appendix 1

Chapter 12. Appendices

12.1 Appendix 1: Hindlimb Anatomy This appendix documents the muscles innervated by the nerves of the hindlimb that have been considered in this thesis (Getty, 1975).

12.1.1 Lumbar plexus

12.1.1.1 Femoral nerve The femoral nerve innervates:

Psoas major Function: flex the hip and rotate the thigh laterad

Nerve(s): femoral and lumbar

Iliacus Function: flex the hip and rotate the thigh laterad

Nerve(s): femoral and lumbar

Quadriceps femoris (four divisions; vastus lateralis, rectus femoris, vastus medialis, vastus intermedius) Function: extensors of stifle (4 branches) and flexes

hip (rectus femoris only)

Nerve(s): femoral nerve

Sartorius Function: flex the hip, adduct the limb

Nerve(s): femoral nerve

Gracilis Function: adduct the limb, flex the stifle and extend the hock

Nerve(s): - saphenous and/or obturator

Pectineus Function: adduct the limb, flex the hip

Nerve(s): saphenous and/or obturator

12.1.1.2 Obturator nerve The obturator nerve innervates:

Adductor Function: adduct the limb and extend the hip

Nerve(s): sciatic or tibial and obturator

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Appendix 1

Pectineus Function: adduct the limb, flex the hip

Nerve(s): saphenous and/or obturator

Quadratus femoris Function: extend hip and adduct the limb

Nerve(s): obturator and sciatic

Obturatorius externus Function: adduct the limb and rotate it laterally

Nerve(s): obturator

Obturator internus Function: rotate the limb laterally

Nerve(s): obturator

Gracilis Function: adduct the limb, flex the stifle and extend

the hock

Nerve(s): saphenous and/or obturator

12.1.2 Sacral plexus

12.1.2.1 Cranial gluteal nerve The cranial gluteal nerve innervates:

Tensor fascia lata Function: flexes hip joint, extend stifle

Nerve(s): cranial gluteal

Gluteus medius Function: extend hip, abduct the limb, rotate femur

Nerve(s): cranial gluteal, caudal gluteal and sciatic

Gluteus profundus Function: abduct the thigh and rotate it medially

Nerve(s): cranial gluteal

12.1.2.2 Caudal gluteal nerve The caudal gluteal nerve innervates:

Gluteobiceps Function: extend the hip, stifle and hock and also flex

the stifle and abduct the limb

Nerve(s): caudal gluteal and sciatic or tibial nerve

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Appendix 1

Gluteus medius Function: extend hip abduct the limb, rotate femur

Nerve(s): cranial gluteal, caudal gluteal and sciatic

12.1.2.3 Sciatic nerve The sciatic nerve innervates:

Gluteus medius Function: extends hip, abducts the limb, rotates

femur

Nerve(s): cranial gluteal and sciatic nerves

Gluteobiceps Function: extend the hip, stifle and hock, flex the stifle

and abduct the limb

Nerve(s): caudal gluteal and sciatic or tibial nerve

Semitendinosus Function: extend the hip and hock, flex the stifle and

rotate limb medially

Nerve(s): caudal gluteal, sciatic or tibial

Semimembranosus Function: extend the hip and adduct the limb

Nerve(s): sciatic or tibial

Adductor Function: adduct the limb and extend the hip

Nerve(s): sciatic or tibial and obturator

Quadratus femoris Function: extend hip and adduct the limb

Nerve(s): obturator and sciatic

Gemelli Function: rotate the femur laterally

Nerve(s): sciatic

12.1.2.4 Peroneal (fibula) nerve Peroneal nerve innervates:

Extensor digitorum longus Function: extend the digits, flex the hock

Nerve(s): deep fibular +/- fibular nerves

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Appendix 1

Extensor digitorum lateralis Function: extend the 4th digit

Nerve(s): superficial fibular +/- fibular nerves

Extensor digitorum brevis Function: extend the digits

Nerve(s): deep fibular nerve

Fibularis longus Function: flex the hock and rotate it medially

Nerve(s): deep fibular and fibular nerves

Fibularis tertius Function: flex the hock

Nerve(s): deep fibular nerve

Tibialis cranialis Function: flex the hock

Nerve(s): deep fibular nerve

12.1.2.5 Tibial nerve Tibial nerve innervates: Gastrocnemius Function: flex the stifle and extend the hock

Soleus Function: extend the hock

Flexor digitorum superficialis Function: extend the hock and flex the digits

Flexor digitorum profundus Function: extend the hock and flex the digits

Popliteus Function: flex the stifle

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Appendix 2

12.2 Appendix 2: Examination Sheet

Farmer’s Name ...... COW CODE: Property Address ………… ………………………….…Phone: ……………...... COW ID: Breed: Date: Age:

Body Weight(kg) Condition Score: 3 3.5 4 4.5 5 Calving Date: 5.5 6

Lactation Springer Fresh Early Lact Mid Lact Late Lact Dry Young Status: Calved History :

Primary Diagnosis: Milk Fever, Grass Tetany Pregnancy Toxaemia, Calving Paralysis Back Injury Other:

Peracute Illness: Salmonella, Grain Overload, Mastitis, Other:…………………………………………….

Primary Diagnosis diagnosed by: FARMER VET

Primary Treatment Date: Drugs:

Secondary Complications (prior to my visit):

Nursing Conditions (prior to my visit):

EXAMINATION: DATE:…… ………………….. (weather conditions)

ALERT: YES (proceed) NO (Go to Non Alert Section)

SIT POSITION: Normal Lateral Medial Caudal Anterior Sternal Left Leg: Normal Lateral Medial Caudal Anterior Sternal Right Leg: Able to Swap Sides YES NO If NO: If NO: Sits on LEFT Sits on RIGHT side side BACK EXAM: Pain Grade: Location: Spinous Processes: NO / Mild Thoracic Dorsal displaced: YES Moderate Lumbar N / Y Severe Pelvic …………………. Lateral displaced: N / Y ……………...... PELVIC EXAM: Lumbosacr Grade: Fracture: al NO / YES Mild / Mod / Instability: Severe

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Appendix 2

HIND LIMB EXAM: Hip LEFT: NO RIGHT: NO Dislocation YES………….. YES……….

Muscle Damage: NO Normal (YES) Swollen Hard Ruptured Hamstring / YES Gastroc Stifle Patella Damage: Reflex - Absent Reduced Normal Increased NO / YES LEFT: Absent Reduced Normal Increased RIGHT:

SENSATION: (Tested Needle Electric Prodder with) Metatarsus: Skin Temp LH anterior Absent Reduced Variable Normal LH caudal Absent Reduced Variable Normal RH anterior Absent Reduced Variable Normal RH caudal Absent Reduced Variable Normal

Pastern: Skin Temp LH anterior Absent Reduced Variable Normal LH caudal Absent Reduced Variable Normal RH anterior Absent Reduced Variable Normal RH caudal Absent Reduced Variable Normal

Deep Pain: Inter Digital LEFT Absent Reduced Variable Normal Temp RIGHT Absent Reduced Variable Normal

Electrostimulation: Absent Mild Moderate Normal LEFT Absent Mild Moderate Normal RIGHT FORE LIMB EXAM: Normal Fracture Dislocation Other

Sensation to Pastern: Absent Reduced Variable Normal LF Absent Reduced Variable Normal RF Deep Pain: Absent Reduced Variable Normal LF Absent Reduced Variable Normal RF MOTOR FUNCTION: Rising Ability: 0% 25% 50% 75% 100% Hind Leg Tendency: LEFT leg Normal Lateral Medial Caudal Anterior RIGHT leg Normal Lateral Medial Caudal Anterior

Lifted: YES / NO If not, why not? Weight Bearing Ability: 0% 25% 50% 75% 100% LH 0% 25% 50% 75% 100% RH 0% 25% 50% 75% 100% LF 0% 25% 50% 75% 100% RF Hind Leg Tendency: Hyperflex LEFT leg Normal Lateral Medial Caudal Anterior fetlock RIGHT leg Normal Lateral Medial Caudal Anterior Hyperflex fetlock Proprioceptive LEFT HIND LEFT FORE RIGHT HIND RIGHT FORE defect: Yes / No Yes / No Yes / No Yes / No

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Appendix 2

Fore Limb Tendency: LEFT: SHOULDER LEFT: RIGHT: RIGHT: EXTENSION TEST: COMMENTS: ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……… CLINICAL PATHOLOGY: BLOOD Taken: Yes / No URINE Dipstix: Myoglobinuria: 0 1+ Results: CK: AST: Other: 2+ 3+ 4+

DIAGNOSIS: PRIMARY DIAGNOSIS:

Original Dx verified: YES / NO If NO – amended Dx:

SECONDARY DIAGNOSIS: No Apparent Muscular Strain Fractured Back Secondary Damage

Lumbosacral Strain Hip Dislocation Myocompartment Ruptured Stifle Syndrome Sciatic: LEFT Grade 1 Grade 2 Grade 3 Grade 4 RIGHT Grade 1 Grade 2 Grade 3 Grade 4 Peroneal: Tibial: Femoral: Obturator: Radial: Brachial LEFT LEFT Grade: LEFT LEFT LEFT Plexus: RIGHT RIGHT 1, 2, 3, 4 RIGHT RIGHT LEFT RIGHT 1, 2, RIGHT 3, 4 Other Findings:

Sciatic Grades reconfirmed at end of examination? LEFT: YES / NO RIGHT: YES / NO

NURSING: Initial Location: Paddock Yard Shed Other Surface: Soft Medium Hard Conditions: Wet Cold Mild Hot Extreme When moved to Date: Nursing Location: Time of Day: Nursing Location: Paddock Yard Shed Other Shelter: YES NO Conditions: Wet Cold Mild Hot Extreme Bedding: Gravel Depth of Bedding: Grass Dirt Concrete Hay Sand Sawdust

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Appendix 2

Remains on Bedding: YES NO Barriers to Restrict: YES NO

Surface: SOFT MEDIUM HARD Lifting: NO No Equipment No Time Counter productive Lifting: Equipment: YES Lifting: How Often? Once daily Twice Daily Other Lifting: Effective: Effective: NO Supervised: Supervised: YES YES NO Rolled side to side (only if cow not able NIL Once a day Twice daily Other to do) TLC Factor: Poor Average Good Excellent Labour: QUALITY: Poor Moderate Excellent

QUANTITY: Low Moderate Plenty

Quality of Nursing: Poor Average Good Excellent

Comments:

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Minerva Access is the Institutional Repository of The University of Melbourne

Author/s: Poulton, Phillip

Title: Examination, diagnosis, prognosis and management of downer cows

Date: 2015

Persistent Link: http://hdl.handle.net/11343/56711

File Description: Examination, diagnosis, prognosis and management of downer cows