Veterinary Services

Generalised and Systemic conditions

In Aberdeenshire, an investigation of wasting in North American bison (Bison bison) was carried out. A local herd of bison was established in 1999 and the animals reportedly thrived with minimal intervention. In 2003 the herd was expanded with the addition of 28 heifers and two bulls from Ireland. A problem with liver fluke was confirmed in previous years and the animals are now treated for fluke and worms regularly. However a problem of wasting and scour has been observed since the expansion of the herd, and predominantly, although not exclusively, affecting added animals. 15 deaths in adult animals have been reported. The most recent animal to be affected was a three-year-old female from the home herd which was euthanased after a six week history of scour and weight loss, weighing only 190 kg at submission. Gross and histopathological examination confirmed the presence of gastrointestinal parasitism, oesophageal ulceration, systemic mycosis suggestive of immunocompromise and a severe ileotyphlitis. Further investigations into this outbreak are being carried out.

A 10-week-old Holstein Friesian female calf was submitted for postmortem examination to the Perth Disease Surveillance Centre (DSC) following a history of dyspnoea and coughing for several weeks; one of several heifer calves which had failed to thrive in recent batches. At necropsy there was an extensive anteroventral consolidation of the lungs. However, no significant bacterial isolates were cultured, probably a consequence of ante mortem antibiotic use. Bovine Viral Diarrhoea Virus (BVDV) was isolated in cell culture from this case.

A blood sample from a five-month-old Limousin cross calf, which was showing signs of diarrhoea and weight loss was submitted for BVD serology. The herd in Ross-shire had a recent history of mucosal disease. Serology for BVD antibody was negative and, as suspected, positive for BVD antigen. Further sampling identified a number of persistently infected (PI) calves. A group of in-calf heifers had been purchased which were sold as being antibody positive, which the farmer interpreted as being safe. Some of them had produced PI calves, which had introduced infection to this naïve herd.

Respiratory tract conditions

At the Inverness DSC, an eighteen-month-old Limousin heifer was one of a group, which exhibited tachypnoea and hyperpnoea. Lungworm larvae had been identified in faecal samples by Baermann examination. The group were treated with an avermectin anthelmintic and all improved apart from this one case which died less than 48 hours after treatment. The lungs were oedematous and consolidated with only about 20% of normal lung tissue remaining. Small numbers of very small lungworm larvae were detected in the terminal airways. On histopathology there was dramatic necrosis of the alveolar walls with intra-alveolar fibrin leakage and increased numbers of intra-alveolar macrophages. There was proliferation of type II pneumocytes and hyaline membrane formation. Multinucleate syncytia and eosinophils were present within the alveoli and around the vasculature. The findings were of a severe acute interstitial pneumonia consistent with a hypersensitivity response to lungworm following the anthelmintic treatment.

Two Holstein-Friesian heifers from a 400 cow dairy herd in Morayshire were submitted for necropsy after demonstrating respiratory distress. Infectious Bovine Rhinotracheitis (IBR) was suspected. In both cases the tracheal mucosa was hyperaemic and had multiple petechial haemorrhages. One heifer had a severe fibrinous pleurisy and pericarditis. Both had very severe bronchopneumonia with bronchiectasis and consolidation of the cranial lobes and ventral parts of the diaphragmatic lobes. The second heifer also had an interstitial pneumonia of the caudal lobes with marked interlobular oedema, emphysema and haemorrhage into the airways. Dictyocaulus viviparus larvae were present in the lower airways of this animal. A profuse growth of Mannheimia haemolytica was isolated in culture from the lung of the first heifer. No IBR virus was isolated in either case and viral Fluorescent Antibody Tests (FAT’s) were negative.

Alimentary Tract Conditions

Chronic liver fluke problems were identified in cows and young adult cattle in five herds at the Thurso centre. The presenting signs were usually scour and weight loss. A faeces sample from a six-month-old suckler calf proved to have fluke eggs present despite there being no signs of disease.

Diseases of the Circulatory System

Two cases of Babesiosis (red water) were diagnosed at the Inverness DSC. A beef cow in a herd in Sutherland presented in poor condition and with pale mucosae. Large numbers of erythrocytes containing Babesia-like inclusions were detected on a Leishman smear. Red water was also diagnosed in a five year old cow, which was dull, weak, anorexic, constipated and anaemic. Babesia-like inclusions were again seen in the red cells.

In Dumfriesshire, a three-year-old Holstein cow that had calved in January suffered milk drop and anorexia for 2 weeks. She was reported to be walking as if in pain and had lost a lot of condition. At postmortem examination crumbly, yellow, fist sized, endocarditis lesion was present on the right atrioventricular valve. Secondary abscesses were found in the lungs, kidneys and spleen.

Also in Dumfriesshire, a three-month-old Limousin cross heifer which had a history of forelimb lameness due to a suspected haematoma in the elbow region was submitted for postmortem examination. She died after a short period of dyspnoea. The mass over the elbow was found to be made up of white fibrous tissue. A similar mass was present in the mediastinum compressing the heart. Histopathology diagnosed a round cell tumour, probably a lymphoma.

Nervous system disorders

A large outbreak of botulism was investigated at the Dumfries DSC. 203 fattening animals ranging in age from 16 to 30 months died and 616 housed cattle fed a total mixed ration (TMR) were affected. Animals outdoors were unaffected and there was no history of access to poultry litter. 71 animals died or were euthanased in the first week and 117 in the second. The final animal was euthanased one month after the outbreak began. The clinical signs were very variable and progressed to lateral recumbancy in many cases with no hope of recovery (figure 1). Mildly affected animals appeared normal on inspection as they continued to ruminate while sitting down. They were stiff or weak when made to rise and reluctant to move away. The ration consisted of hay, straw, silage, biscuit meal, vegetables, sugar beet pulp, bread, brewer’s grains and minerals. All tests on postmortem samples and feeds were negative for Clostridium botulinum and its toxins. The vegetables were suspected as the most likely source of the problem.