Examination, Diagnosis, Prognosis and Management of Downer Cows
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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 i 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. ii 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 iii 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. v 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. vii 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.