Veterinary Services

Alimentary tract diseases

In the Borders, two Aberdeen Angus cows were reported to have become anorexic on the same day. These were from a housed group of 200, fed pit silage and a home-mixed concentrate. One cow subsequently died and the carcass was submitted to St Boswells Disease Surveillance Centre (DSC) for necropsy. The cow was found to be in a state of severe dehydration and to have blood at the anus. Internal examination revealed pericarditis and pleurisy over the diaphragm. Purulent tracts were followed from the diaphragm back to the reticulum. A four centimetre piece of tyre wire was found to be associated with this lesion. The owner was advised to examine the silage pit for deteriorating tyres and to remove them immediately.

Traumatic reticulitis was also confirmed by Ayr DSC at necropsy of a six-year-old Charolais cow. A bag-tie was present in a reticular abscess and there was associated peritonitis, pericarditis and lung consolidation. This was the fourth death in the 50-cow herd in a 10-day period. Interestingly the case necropsied was also seropositive for Malignant Catarrhal Fever (MCF) on an ante-mortem blood sample raising the possibility that both conditions were involved in the group mortality.

Respiratory tract diseases

A four-and-a-half-year-old Holstein cow was submitted for post mortem following an outbreak of pneumonia in a 1,000 head bull beef / dairy herd. Two to three cases of pneumonia were being diagnosed per week with all ages of stock affected. The cow submitted had deteriorated clinically over a 10 day period and was euthanased. At post mortem an extensive, chronic, purulent pneumonia was evident. The lesions were consistent with a complex, chronic, active bacterial-type bronchopneumonia with suspected mycoplasma involvement. Fluorescent antibody tests (FAT) for respiratory viruses were negative. Arcanobacterium pyogenes was isolated from the lesions although no significant mycoplasma species were isolated.

A second four-year-old dairy cow was submitted for post mortem approximately three weeks later. Pathology was similar to the first case although on this occasion Mycoplasma bovis was isolated. Subsequently, two nasal swabs were submitted from similarly affected cows from which Bovine Herpes Virus type 1 (BHV1) was isolated in cell culture and on a further nasal swab BHV1 was detected by FAT. The herd was subsequently vaccinated with live attenuated BHV1 vaccine and the clinical situation has markedly improved.

A six-month-old calf from a Selkirkshire farm (one of four similar cases) was treated for pneumonia but failed to respond satisfactorily. On post-mortem examination, extensive areas of necrotic ulceration were noted around the pharynx and larynx, which extended to a severe necrotic tracheitis. The lungs were showed around 60% consolidation, with the consolidated areas containing multiple small abscesses. On further examination multiple haemorrhagic lesions were noted in the mucosa of the reticulum, omasum and along much of the small intestine. Multiple large lesions were seen in the liver, and the kidneys also showed a smaller number of infarct-type lesions. Although Bovine Virus Diarrhoea (BVD) virus isolation and FAT analysis of scrapes from the tracheal mucosa for BHV1 were negative, histopathology identified changes in the respiratory tract and intestine consistent with Inectious Bovine Rhinotracheitis (IBR). Other lesions were consistent with fungal invasion of the gut lesions and subsequent embolic spread of that infection.

Reproductive tract conditions

A foetus was submitted to Inverness DSC to investigate the fourth abortion in a BVD accredited Simmental herd. Bacillus licheniformis had been isolated from the foetal stomach contents of two previous cases. This fourth foetus had severe cerebellar hypoplasia to the extent where it was almost cerebellar aplasia. The left and right cerebrum were also severely cavitated and filled with fluid leaving only a very narrow rim of grey matter. BVD virus was isolated from the spleen.

Nervous system disorders

A six year old Aberdeen Angus cow from a herd in Sutherland had a sudden onset of nervous signs. It was pyrexic (104F), head shaking and had collapsed. There was no evidence of hypomagnesaemia or lead poisoning. Antibody to louping-ill virus was detected at a titre of 1/160, much of which was IgM confirming recent louping-ill infection.

Generalised and systemic conditions

In the Borders, five two-month-old calves died from a group of 25, born at the end of the autumn calving period. All five calves, which had died over the course of a month, were treated for pneumonia prior to death. When two of the carcases were examined there was clear evidence of a bacterial pneumonia, but also of erosions within the intestinal tract, these being most severe in the abomasum. Bacterial cultures confirmed the presence of Pasteurella multocida and Mannheimia haemolytica in the affected lung, but virus isolation on thyroid tissues also confirmed the presence of Bovine Viral Diarrhoea (BVD) virus. Additional screening for BVD within the rest of the herd was recommended.

A week old Limousin calf was submitted to the Dumfries centre with a history of weakness since birth, nasal discharge and thickened navels. 100 calves had been born on the farm with no problems, however a group of 12 similarly affected calves had been born, 5 of which had died in the first week of life. Pinpoint abscesses were present throughout the liver, and Listeria monocytogenes was isolated from the liver, lung and spleen. The calf was small (weight 27kg) and was considered to be premature at birth, suggesting a possibility that this was an in-utero infection, resulting in the birth of weak affected calves.