LARGE ANIMAL | METABOLIC DISEASE ONLINE EDITION
Milk fever – an overview Milk fever or periparturient hypocalcaemia, is a metabolic disease of dairy cows that occurs around the time of calving. During the dry period, calcium requirements are relatively low; but at calving there is a sudden increase in calcium requirement as lactation begins. If this demand is not met quickly enough, the concentration of calcium in the blood drops below a critical threshold, resulting in either clinical or subclinical milk fever. Jenny Bellini BVSc MRCVS A cow can lose 23g of calcium 10 in 10 litres of colostrum in Jenny qualified from the one milking; yet, typically, only has 12g of free calcium 9.0 University of Bristol in 2014 8 available to her. This huge and started working soon 8.0 after for Friars Moor Livestock demand for calcium must be Health – a member practice met from elsewhere to prevent of XLVets*. Jenny works milk fever developing. The 6 primarily in dairy practice, average incidence of clinical with particular interests in milk fever in the UK dairy herd 4.8 nutrition, heifer rearing and is four to nine per cent, while 4 block-calving systems. the incidence of subclinical milk fever is estimated to be between 25 to 50 per cent. Times more likely 3.0 *XLVets is a community 2 2.6 The average cost of a case of of independently-owned, 2.0 progressive veterinary milk fever is approximately 1.7 practices that work together to £200 (Husband, 2005). achieve the highest standards 0 of veterinary care. As plasma calcium is required LDA 30d) for neuromuscular function, Mastitis Ketosis www.xlvets.co.uk Metritis Dystocia Retained milk fever is characterised placenta by decreased feed intake, Culling (1- decreased heart rate, Figure 1. The incidence of other conditions associated with milk inhibition of urination and fever (Source: EBVC, 2011). defaecation, rumen and intestinal stasis and reduced rectal temperature. If it is left untreated, cows progress to lateral recumbency, and eventually coma and death.
Reduced feed intake leads to greater fat mobilisation, and one study (Reinhardt et al, 2011) has shown cows with low blood calcium levels post calving (<2mmol/L) have higher concentrations of non- esterified fatty acids (NEFAs). 0.75 As muscle contraction is hours* inhibited, the teat sphincter relaxes; which leads to an increased risk of mastitis. Hypocalcaemia post calving also directly impairs immune *Suggested Personal & Professional cell response to an activating Development (PPD) stimulus, therefore making these cows more susceptible to disease. As shown in Figure 1, the METABOLIC DISEASE incidence of mastitis and Figure 2. A cow with milk fever and metritis. ketosis in cows recovering from
46 VETERINARY PRACTICE TODAY | VOLUME SEVEN | ISSUE ONE | 2019 WWW.VETCOMMUNITY.COM | ONLINE EDITION