Chris Livesey

Hock injuries in cattle kept in straw yards or cubicles with rubber mats or mattresses

Hock damage is one of the most common traumatic injuries suffered by dairy cows, but most hock injuries should be avoidable. This study investigated the effect of housing system on the development of hock damage in first lactation Holstein heifers. After calving, 60 heifers were randomly allocated to either straw yards, cubicles with butyl rubber mats or cubicles with mattresses filled with chopped tyres. The hocks of these heifers were examined in the first week after calving (week 1) and in weeks 6, 12 and 26 of lactation. Hock damage was scored as either 1 (hair loss only) or 2 (all other damage). Heifers housed in cubicles with mats had significantly worse lesions at week 26 than at week 1, while there was no change in heifers housed in cubicles with matresses, and heifers housed on straw had significantly lower lesion scores. Additionally, heifers with no lesions at calving were significantly more likely to develop lesions when kept on mats than heifers kept on straw or mattresses. These data suggest that replacing mats with mattresses in cubicles can result in a significant reduction in traumatic hock injury.

Suspected botulism in dairy cows and its implications for the safety of human food

A large outbreak of suspected botulism occurred on a dairy farm. The affected animals were listless and showed signs ranging from hindlimb unsteadiness to lateral recumbency, although the most common presentation was sternal recumbency with an apparent hindlimb weakness when stimulated to rise. Postmortem examinations revealed no conclusive gross pathology or histopathology. The affected cattle were found to have neutrophilia and hyperglycaemia with no other consistent haematological or biochemical abnormalities. The combination of clinical signs, disease epidemiology and the ruling out of other differential diagnoses strongly supported a diagnosis of unconfirmed botulism; however, the source of toxin was not demonstrated. Botulism is a severe disease in human beings and there are uncertainties about the pharmacokinetics and pharmacodynamics of Clostridium botulinum toxins. In such circumstances, a precautionary approach to food safety is essential. Restrictions were placed on the movement of livestock and sale of milk from the farm premises until 14 days after the onset of the last clinical case.

Emergence of suspected type D botulism in ruminants in England and Wales (2001 to 2009), associated with exposure to broiler litter

Scanning surveillance by the Veterinary Laboratories Agency revealed the emergence of suspected botulism in ruminants in 2003, presented as flaccid paralysis. From 2003 to 2009, 168 cattle and 19 sheep incidents were recorded, with mortality between 5 and 80 per cent. All sheep incidents and 95 per cent of cattle incidents had proximity to broiler litter. From July 2006, the gut contents collected from 74 affected cattle and 10 affected sheep were tested for Clostridium botulinum toxins using mice bioassays and for organisms by culture. Type D toxin was identified in 32 per cent of cattle and 18 per cent of sheep samples. C botulinum type D organisms were identified in 40 per cent of cattle and 30 per cent of sheep samples, but broth from one sample reacted with C and D antisera. Type C botulism has previously been reported more commonly than type D in the UK and has been associated with the use of poultry litter as fertiliser, bedding or feed. The almost exclusive association with C botulinum type D toxins or organisms in the gut contents in this survey suggests a change in the source or epidemiology of botulism in the UK. The source of C botulinum type D was uncertain. Broilers may carry C botulinum type D in their gut flora subclinically. The emergence of a new type D strain, or changes in broiler husbandry and nutrition, medication and other enteric infections may have affected colonisation with C botulinum. Further investigation of poultry and farm environments for sources of type D awaits the development of tests for C botulinum toxins that do not require the use of mice.

The assessment of blood copper status in cattle: A comparison of measurements of caeruloplasmin and elemental copper in serum and plasma

Abstract AIM: To evaluate the effect of test, either copper (Cu) concentration or caeruloplasmin (CP) activity, and sample type, either serum or plasma, on the diagnosis of blood Cu status in cattle. METHODS: Paired serum and heparinised plasma samples taken from 125 cattle in 13 herds were tested for Cu concentration and CP activity. The individual results for serum Cu concentration and serum and plasma CP activities were compared with the plasma Cu concentration results, as were their diagnostic values as determined by reference ranges, i.e. ‘marginal’, ‘adequate’, ‘excess’. RESULTS: The overall mean serum Cu concentration was 2.92 µmol/L lower than the mean plasma Cu concentration; however, there was significant variability between individual samples, and the 95% limits of agreement ranged from 0.44 µmol/L more to 6.28 µmol/L less. The relationship between CP activity and plasma Cu concentration was less variable; the 95% prediction interval for plasma Cu concentration from CP activity was ± 2.8 µmol/L, and was unaffected by whether CP activity was measured in plasma or serum. Using the threshold currently recommended for ‘marginal’ status of <8.0 µmol/L for serum Cu concentration identified a significantly different population of cattle than a threshold of <9.0 µmol/L for plasma samples. Altering the threshold to <7.0 µmol/L for serum Cu concentration produced better agreement. For CP activity, a threshold of 15 IU/L for both serum and plasma identified the same population as a threshold of <9 µmol/L for plasma Cu concentration. CONCLUSIONS: Serum Cu concentration is not a suitable substitute for plasma Cu concentration for the detection of ‘marginal’ blood Cu status in cattle as the individual variability in the apparent loss of Cu during clotting is too great. In this study, CP activity, in both serum and plasma, was found to be a suitable substitute for the detection of ‘marginal’ blood Cu status. CLINICAL RELEVANCE: The use of serum Cu concentration rather than plasma Cu concentration in the diagnosis of Curesponsive disease in cattle needs to be re-evaluated as does the way in which individual sample results are used in such tests.

Lead poisoning in cattle and its implications for food safety.

The lead poisoning incidents in cattle investigated by the Veterinary Laboratories Agency between 1990 and 2003 are reviewed. Lead poisoning was most commonly encountered in young calves, but cattle of all ages were affected. The lead was derived mainly from lead paint, lead accumulator batteries and lead in soil from old mine workings. Paint was responsible for the majority of cases of poisoning in young calves; yearling animals were most at risk from discarded batteries, and adult cows were most commonly poisoned by geochemical sources of lead. There was a marked seasonal incidence, with most cases occurring after turnout in the spring and early summer.

Surveillance of suspect animal toxicoses with potential food safety implications in England and Wales between 1990 and 2002

The potential chemical contamination incidents investigated by the Veterinary Laboratories Agency (VLA) between 1990 and 2002 are reviewed. Incidents were identified in the course of the VLA’s surveillance of food animal disease and further investigations were carried out on behalf of the Food Standards Agency in order to identify and control the contamination of food animals and animal products with chemical hazards. In total 876 incidents were investigated, of which 588 involved the poisoning of cattle with heavy metals. There were 63 incidents involving the exposure of cattle, sheep, pigs and poultry to the accidental misuse of veterinary medicines, pesticides or rodenticides, and 50 incidents involving their exposure to microbiological toxins, particularly botulism.

Effect of concentrate composition and cubicle bedding on the development of hoof haemorrhages in Holstein heifers after calving

Diseases of the hoof horn are the most common cause of lameness in the UK dairy herd, and diet, particularly starch intake, is commonly implicated in their development. This study assessed whether replacing starch carbohydrate with sugar beet pulp, in a diet containing 50 per cent of the dry matter as forage, would significantly reduce the development of hoof horn haemorrhages in dairy heifers after calving. It also investigated the effect of replacing wood shavings as cubicle bedding with chopped straw. The heifers fed the high-fibre diet had a significantly lower yield of milk protein and a significantly higher yield of milk fat than the heifers fed the high-starch diet, indicating that the change of diet had affected rumen fermentation. However, the change had no significant effect on the development of hoof horn haemorrhages. The change of bedding material also had no significant effect on the development of hoof horn haemorrhages.

Use of ocular fluids to aid postmortem diagnosis in cattle and sheep

THE use of ocular fluids ‐ aqueous humour and vitreous humour ‐ for postmortem diagnosis, especially of hypomagnesaemia, is controversial. This is usually due to an incomplete understanding, or inappropriate interpretation, of clinical chemistry results. The limitations of sampling, analysis and interpretive information have to be fully understood when dealing with clinical biochemistry, but postmortem measurement of calcium, magnesium, beta‐hydroxybutyrate, urea and nitrates in the ocular fluids of ruminants may be of value. This article discusses the appropriate use of ocular fluids as aids to postmortem diagnosis.

Relationship between acute phase proteins and hoof horn haemorrhages in postpartum first-lactation heifers

As part of a study of the development of hoof horn haemorrhages in first-lactation heifers, measurements were made of acute phase reactants to investigate the link between the acute phase response and the development of the haemorrhages. Over a period of two years, blood samples were taken from two separate groups of heifers, weekly in the three weeks before they calved and then twice weekly until eight weeks after calving. Plasma total protein, albumin, fibrinogen, haptoglobin, seromucoid and serum iron and caeruloplasmin were measured and the relationships between the peak concentration (or activity) or the area under the curve of each acute phase reactant and the peak scores for sole or white line haemorrhages were assessed by linear regression. The results suggested that the development of the hoof horn haemorrhages observed in the study was not accompanied by an acute phase response, and the haemorrhages were therefore not primarily caused by endotoxicosis. The diets and husbandry systems used were typical of dairy farms in the UK and the results therefore suggest that a significant proportion of hoof horn haemorrhages observed in UK dairy cows may not be caused by endotoxicosis.

Diagnosis and implications of botulism

BOTULISM is a neuroparalytic condition affecting birds, mammals and fish, and is caused by exposure to toxins produced by various biotypes of Clostridium botulinum. Until a few years ago, botulism was considered to be a rare disease in farm animals in the UK. However, since 2003, there has been an upsurge in the number of suspected cases reported, particularly in cattle and more recently sheep. The diagnosis of botulism is problematic and relies heavily on clinical signs. Confidence in the diagnosis is improved by identifying the risk factors and suspect sources, and by ruling out the more common differential diagnoses. This article describes the clinical signs of classic and atypical disease, and discusses the implications of a diagnosis of botulism with regard to animal welfare, food safety and public health.