Veterinary Services

Parasitic diseases

Chronic liver fluke problems were a common diagnosis across Scotland this month. In Caithness the condition was noted in eight beef suckler herds affecting cows and calves. In some cases animals had been treated in mid summer with a flukicide but had been re-infected in the wet weather of September and October.

Again in Caithness six groups of cattle aged six to eighteen months were diagnosed with parasitic gastro-enteritis. In one case calves still with their dams had been treated with avermectin in October but had remained at grass and been re-infected. The good grazing season this autumn encouraged farmers to leave cattle at grass for longer.

Generalised and systemic disorders

The seasonal rise in the number of outbreaks of salmonellosis was noted this month. An outbreak of salmonellosis due to infection with Salmonella Dublin was confirmed on an Aberdeenshire beef suckler unit. The owner reported 42 cows calving in the preceding two weeks with a sudden dramatic increase in mortality in the neonatal period. Eight deaths in calves in the first week of life were reported. Colisepticaemia was initially suspected but not confirmed at postmortem examination of the first calf submitted. A light growth of Salmonella Dublin was eventually obtained on enrichment from the liver. However a profuse growth of Salmonella Dublin was obtained from multiple organs from a second (stillborn) calf submitted two days later.

A two-month-old Holstein heifer died after treatment for pneumonia. The farm had lost calves due to acute pneumonia the previous year. Vaccination resulted in no improvement. Pneumonia was confirmed at necropsy at the Dumfries centre but cultures were sterile. Salmonella Dublin was isolated on enrichment and histopathology confirmed changes in the lung, liver and spleen that were consistent with salmonella septicaemia.

Alimentary Tract Disease

A Jersey herd in Dumfriesshire lost four calves in one week due to acute scour. A four-day-old heifer was submitted for necropsy. It had been born outside and given two litres of colostrum by stomach tube. The calves remained with the cows for 24 hours before being moved into single pens. The navels were not routinely treated. There were no gross changes at necropsy but histopathology revealed an extensive abomasitis and enterotyphlocolitis. Tests for E. coli K99 were positive and in addition BVDV was isolated from the spleen in cell culture. The Zinc Sulphate Turbidity (ZST) test result was 5 suggesting inadequate colostrum intake.

Respiratory tract diseases

Infectious bovine rhinotracheitis (IBR) was the most common cause of pneumonia diagnosed across Scotland. Clinical signs included various combinations of ocular discharge, nasal discharge, coughing and fever. Adult cows also suffered a significant milk drop. Diagnosis was confirmed by the demonstration of IBR virus in ocular or nasal swabs by immunofluorescence. The involvement of IBR was also suspected in some cases of fatal pneumonia, but although histopathological examination of such animals showed a tracheitis suggestive of IBR it was not possible to demonstrate the virus in the post mortem material.

A six-month-old Simmental cross calf from a unit in Angus was submitted for necropsy, with a history of death despite a period of treatment for pneumonia. Examination revealed an appreciable volume of straw-coloured pleural fluid, pulmonary congestion and oedema. In addition a 2-cm diameter abscess was found within the wall of the left ventricle of the heart. Subsequently Bovine Herpes Virus type 1 (BHV1) was detected in the lung by FAT and Histophilus somni (Haemophilus somnus) was isolated on culture of the abscess.

A seven-month-old Simmental cross Charolais heifer died suddenly but had been a poor doer for some time. The weaned calves were housed one week previously and there had been some coughing in the group. The udder was congested and haemorrhagic, which was confirmed on histopathology but there was no evidence of inflammation. There was subcutaneous and intermuscular oedema at the base of the udder and in both hind legs between the hip and stifle area. There were a large number of petechial and ecchymotic haemorrhages in the laryngeal and tracheal area. The tracheal mucosa was intensely congested as was the bronchial mucosa. There were petechial epicardial haemorrhages present. The lungs were congested. FAT’s on the tracheal mucosa were strongly positive for BHV1 but there was no diphtheritic material in the trachea nor evidence of a secondary bacterial pneumonia. Udder and systemic cultures were sterile. Histopathological findings were of terminal circulatory failure and hypoxia.

A six-month-old Limousin cross calf from another holding in Fife was submitted alive but moribund, for postmortem examination. This farm had a history of BVDV-associated disease and a number of other poor-doing calves were currently present on the unit. An acute bronchopneumonia was identified on postmortem examination, from which a pure growth of Mannheimia haemolytica was isolated on culture. In addition a blood sample tested by ELISA for antigen to BVDV produced a result fractionally below the positive cut-off for the test. Advice was given on screening other calves in the same group for evidence of BVDV.

Reproductive tract diseases

Four abortions in seven days were reported in a dairy herd in Ayrshire. Histopathological examination of the brain of three of the aborted calves showed widespread meningoencephalitis of a type normally associated with Neospora caninum infection. Foetal serology for N. caninum was consistently negative, but five dams tested were all seropositive.

Congenital defects were diagnosed as the cause of death in two calves from different farms in the Borders. The first calf was a one-month-old Hereford that died of congestive heart failure and hepatocellular degeneration resulting from a patent foramen connecting the two ventricles. The second calf was a 10-week-old Charolais that had severe bilateral hydronephrosis resulting from a blockage of the urethra. From the history received, both appeared to be isolated incidents.

Skin diseases

A two-year-old Highland heifer had a haemorrhagic, large mass on the lower left neck area, below the jugular furrow. The mass had enlarged over the previous couple of months. Histopathology showed that it was composed of dense fibrous tissue, much of which was organised granulation tissue, containing an intense pyogranulomatous inflammatory infiltrate. At the centre of the inflammation were eosinophilic club bodies. The findings were typical of actinobacillosis but it was not possible to demonstrate the bacteria within the lesion.