Veterinary Services

 
An adult dairy cow losing condition for two months and showing exophthalmos of the left eye was euthanased and submitted to Ayr for postmortem examination. All carcase lymph nodes were enlarged with multiple, pale, circular lesions (Fig. 1 - see top right-hand side). The liver (Fig. 2 - see top right-hand side) was also enlarged with multiple, irregular, pale lesions and areas of necrosis. An irregular mass comprised of several small nodules was present on the mucosal surface of part of the small intestine, and bony masses were also evident on two ribs. Enzootic bovine leukosis could not be excluded on the gross pathological findings and the local Animal Health office was informed. On histopathology the lesions were shown to be a metastatic adenocarcinoma likely to be of intestinal origin that had spread via the lymphatics.

Outbreaks of salmonellosis were recorded across Scotland. In one Dumfriesshire dairy herd pyrexia and milk drop was noted and fifteen calves developed pneumonia.  Calves as young as three days of age were affected and two calves were submitted for postmortem examination. At necropsy both calves showed peritonitis with splenomegaly and enlarged mesenteric lymph nodes. One of the calves also had joint ill and evidence of hypo-gammagobulinaemia. Salmonella Dublin was isolated in septicaemic distribution from tissues.

Salmonella Typhimurium 104 was recovered from faecal samples submitted from suckler cows with pyrexia and diarrhoea. It was reported later that a stockperson had also become ill with a confirmed diagnosis of salmonellosis, highlighting the zoonotic potential of Salmonella organisms.

Respiratory tract diseases

An outbreak of respiratory disease in pregnant suckler cows from Argyll was investigated. Although no animals were purchased recently, cattle had been at shows and returned to the herd without being quarantined. Affected animals were anorexic, coughing and had nasal discharges. They were pyrexic and respiratory rates were raised. Fluorescent antibody tests for bovine herpes virus-1 on nasal swabs proved positive, confirming a diagnosis of infectious bovine rhinotracheitis (IBR).  IBR was also diagnosed on the basis of paired serology in a Dumfriesshire dairy herd after bloods were received from a pyrexic cow that developed milk drop and a nasal discharge.

Reproductive tract diseases

An analysis of necropsy findings in bovine foetuses and stillbirths was undertaken. The data are presented as a combined five year total for the period 2004 to 2008 inclusive (Fig. 3 - see top right-hand side). An outbreak is identified as one or more foetal examinations carried out from a single herd within  one month. No significant trend over the years or difference in frequency of the various diagnoses was identified.  The percentage of outbreaks where a diagnosis was not achieved was 49 per cent (95 per cent  confidence interval (CI) 48 to 51per cent). Bacillus licheniformis was the most frequently made diagnosis with involvement in 13 per cent of outbreaks (95 per cent CI 12 to 15 per cent). The data set is notable for the low frequency with which infections commonly considered as important such as Campylobacter fetus, Salmonella Dublin and bovine herpes virus 1(BHV1) occurred, all being identified in fewer than two per cent of outbreaks.

The data for the period January to August of 2009 (Fig. 4 - see top right-hand side) was compared to the five year period and significant differences were observed. There was a non significant increase in the percentage of outbreaks in which a diagnosis was not reached to 55 per cent (95 per cent CI 51 to 61 per cent) while a signficant drop occurred in the number of diagnoses attributed to Leptospira Hardjo and Bacillus licheniformis. No explanation can be made for the large reduction in numbers of diagnoses of B licheniformis outbreaks as there is a lack of understanding of the risk factors for this disease. In contrast the data for leptospira infections in bovine foeopathy are largely unreliable as the diagnostic tests are insensitive.

The impact that selection of screening test has on these data are further underlined by the relatively low frequency with which Neospora caninum and BHV1 infections are identified. In both infections the routine screening does not utilise the most sensitive molecular and immunohistochemical tests available as these are expensive to carry out and are employed in a restricted number of outbreaks.

Three abortions occurred on an Ayrshire dairy farm in one week and a relatively autolysed foetus and placenta were submitted for examination. A heavy, pure growth of Salmonella Dublin was recovered from foetal stomach contents and in mixed growth from placenta, liver and lung.

Abortion due to Listeria monocytogenes was confirmed on an Aberdeenshire beef unit following submission of a foetus from the third cow to abort. A profuse growth of the organism was obtained on culture of foetal stomach contents.

Skin diseases

Skin scrapes were submitted from zebu cattle that are part of a farm park collection. Two affected animals had flat, circular skin lesions over their heads.  Microscopic examination of the material demonstrated ectothrix fungal spores consistent with ringworm infection. Trichophyton verrucosum was isolated from the sample.