Veterinary Services

At the Dumfries Disease Surveillance Centre (DSC) a nine-week-old Aberdeen Angus heifer was presented for postmortem after being found dead. The farm had lost several calves over the previous six months with Infectious Bovine Rhinotracheitis (IBR); coccidiosis, bacterial pneumonia and lungworm all diagnosed. The carcass in this case was dehydrated and scour was evident. In addition, there was anteroventral lung consolidation from which Mannheimia haemolytica was isolated. Bovine Viral Diarrhoea (BVD) virus was isolated from the spleen. It is possible that the presence of a persistently infected animal and the associated immunosupression associated with BVDV had contributed to the ill health of other calves.

Alimentary Tract Conditions

There was a large increase in the number of cases of necrotisingc enteritis diagnosed in July. Cases generally presented as spring born calves approximately two to four months of age with diarrhoea, straining and often with blood present within the faeces.

Two cases from different locations were submitted to the Perth DSC on the same day. The first case was a seven-week-old Simmental cross calf with a history of black scour. The large intestine was severely ulcerated and dilated with bloody mucosal casts. The second case was a 10-week-old Charolais cross calf with ulceration along almost the entire length of the small intestine. In both cases BVDV infection was ruled out by serology, virus isolation and PCR. Diagnostic criteria for necrotisingc enteritis are based on clinical signs (outlined above) in two to four-month-old calves backed up by gross and histopathological findings suggestive of acute mucosal disease in the absence of BVD virus.

Toxic Conditions

In Aberdeenshire, lead poisoning was confirmed in a three-month-old Limousin calf. Six calf deaths were reported in a group of 15 suckler cows and calves following clinical signs of blindness, twitching and hypersalivation. An old battery was found in the field. The Food Standards Agency was informed and appropriate action taken to protect the food chain.

Nervous disorders

Two Charolais cross heifers were submitted from the same farm one week apart to the Dumfries DSC. Both were two-months-old. The first had been found dead the day after a change of pasture. The second was found dead the day after all the animals had been run through the race checking ear numbers. They were in very good condition and had large milk clots in their abomasa. There was little to see in the first carcass other than autolysis. The second animal had large numbers of petechiae in the tissues of the neck extending down into the mediastinum. The ileum was inflamed and the faeces were soft verging on scour. Small areas of the brain appeared to fluoresce under UV light. Clostridium sordellii was isolated from the first calf and Clostridium perfringens from the second calf. Clostridial toxin tests were negative in both cases. Histopathology of the brains showed lesions consistent with a diagnosis of focal symmetrical encephalomalacia, a condition caused by Clostridium perfringens epsilon toxin. Interestingly the lesions in both calves included necrosis of cerebral cortical grey matter. The findings of fluorescence and cerebral cortical necrosis are not necessarily confined only to the condition cerebrocortical necrosis (CCN) associated with thiamine deficiency.

Diseases of the Circulatory System

Postmortem examination of a well grown, six- week- old, Charolais-cross heifer calf at the Edinburgh centre indicated that her its sudden, unexpected death was due to a complex cardiac anomaly. The heart was markedly enlarged and rounded and detailed examination revealed a high ventricular septal defect, over riding aorta (so the aorta exited the right ventricle above the septal defect), right ventricular dilation and hypertrophy, patent foramen ovale and patent ductus arteriosus. The abdominal vena cava appeared dilated and free fluid was present in the thorax, abdomen and pericardial sac. The abnormalities present would have lead to hypoxia rather than congestive cardiac failure allowing the calf to compensate and appear clinically normal unless exercised or otherwise stressed.

In Dumfriessshire, a ten-month-old Holstein Friesian heifer was found in sternal recumbency and died soon after. There had been one previous death. On postmortem there was a severe fibrinopurulent pericarditis (figure 1; click on PDF link on right). The adjacent muscle was blackened with haemorrhages on the thoracic pleura. A fluorescent antibody test (FAT) on the myocardium was positive for Clostridium chauvoei, which was also isolated on culture from the pericardium, confirming a diagnosis of the cardiac form of Blackleg. The blackleg lesions noted in the adjacent musculature were assumed to be from the leakage of toxins from the primary heart lesion.

Skin diseases

A two-year-old Belgian Blue cross cow lost condition after calving and had developed photosensitizsation. There were small numbers of liver fluke eggs in the faeces, however the GGT level was only marginally elevated at 24iu/l (reference range 8-22iu/l). The GLDH level was increased at 165iu/l (reference range 6-13iu/l) indicating the presence of hepatocellular damage.