Veterinary Services

Toxic conditions

Post mortem examination of a Holstein cow at the Dumfries Centre identified copper poisoning as the cause of acute death. The cow which presented with respiratory signs and a slight nasal discharge tested negative for bovine herpes virus type 1 by fluorescent antibody testing (FAT).

The animal deteriorated and died three days later eventually showing clinical signs of jaundice, and haematuria. The carcass and liver in particular appeared to be jaundiced and the liver copper level was 33,900 m mol/kgDM (reference range 314-7850). One other cow had died on the farm in the last six months, which was not investigated. The Food Standards Agency (FSA) was informed of the case, however no risk to the food chain was identified. Analysis of the silage fed to the cattle and the total mixed ration have identified a copper inclusion level in the ration three times the requirement of high yielders. Changes to the mineral supplied are in progress.  

Generalised and systemic conditions 

Salmonella Dublin was commonly isolated as a cause of disease in September. In Ayrshire, tissues submitted from a field necropsy of a seven-day-old dairy calf that was collapsed and pyrexic before death yielded the organism. The herd also had a problem of pyrexia of unknown origin in adult cattle. Also in Ayrshire, Salmonella Dublin was recovered from a four-year-old diarrhoeic, pyrexic Holstein cow in another herd and a dairy cow in a further herd that aborted showed metritis and scour due to Salmonella Dublin.

In Invernesshire, further investigations are being carried out to try and determine the source of a Salmonella Dublin infection in a suckler herd, which resulted in the isolation of the organism from watercourses in six different fields. The same agent was diagnosed in adult cattle on another nearby holding in Inverness-shire and investigations carried out there also identified the organism in some of the watercourses.

Since a peak in 2002 a decrease in the incidence of disease outbreaks associated with Salmonella Dublin in cattle has been observed. Figure 1 (see link on right) shows the number of outbreaks by year as a percentage of the diagnosable submissions showing a 45% decrease in Salmonella Dublin incidence between 2002 and 2004. Complete data for 2005 is not yet available and it remains to be seen whether or not this trend will continue.

Figure 2 (see link on right) shows the temporal distribution of Salmonella Dublin diagnoses 2002-2005. In 2002 and 2003 a marked peak in the number of diagnoses occurred in the late autumn and early winter months. This was not evident in 2004 with a more even distribution of cases throughout the year. This may reflect the lower number of cases seen in 2004. Traditionally the peak has been associated with housing stress and stress associated with an increased number of calvings and abortions seen at that time.

Serology for malignant catarrhal fever (MCF) antibody was confirmed positive in a 14-month-old Limousin Cross stirk with a two-day history of scour. The stirk subsequently died and was submitted to the Perth Centre for post mortem examination. Diffuse petechiation was evident along the length of the small and large intestinal mucosa, which was raised in pale micronodules with linear, black striping towards the rectum. Histopathology provided supportive evidence of a diagnosis of MCF and ovine viral herpes virus–2 (OVHV-2) DNA was detected by polymerase chain reaction (PCR).

Alimentary tract disorders

Two, recently calved, adult dairy cows were submitted to the Perth Centre for post mortem examination following acute deaths. The first case showed acute milk drop followed by sudden death. The second case was breathing heavily although no cause for this was determined and was found dead the following morning. Post mortem examination of both carcasses revealed dehydration and right abomasal displacement with gaseous distention of displaced organs and a torsion of the omasum and reticulum in one case. In both cases the rumen contained fibrous material and a moderate quantity of grain was present (pH 6). Blood minerals collected prior to death but post treatment were within the reference ranges. Dietary management of the herd, particularly post-calving, was under review.

A three-month-old suckler calf died suddenly in a herd in Sutherland. Severe peritonitis was present, the umbilicus was swollen (2.5cm in diameter) with a necrotic, thickened tract in the round ligament. Large numbers of ticks (Ixodes ricinus) were attached to the carcass. Serology for tickbornefever proved negative.

Respiratory tract conditions

Dictyocaulus viviparous (lungworm) infection and bacterial pneumonia were confirmed in a 16-month-old beef heifer found dead in Ayrshire after three of 80 animals died on rented grazing. Lungworm larvae were recovered from the faeces of yearling dairy-bred animals on another farm. The group of 48 had been outside for seven weeks and had shown respiratory disease affecting most of the group during the previous three weeks.

Nervous system disorders

An 18-month-old Hereford stirk was submitted for post mortem examination to the Perth Centre. The animal had been born with one eye only and had been ill-thriven ever since. The stirk had recently started to scour and was euthanased on welfare grounds. Post mortem the small intestine showed inflammation and thickening suggestive of parasitic gastroenteritis. Although the faecal worm egg count proved negative, histopathology confirmed enteritis consistent with helminth challenge. Screening of a blood sample obtained prior to euthanasia proved negative for bovine virus diarrhoea (BVD) antigen and antibody. Neuropathology revealed cerebellar hypoplasia, a congenital malformation of unknown aetiology.

Reproductive tract disorders

Stillbirth due to infection with E. coli was suspected in a full term calf with atelectatic lungs at the Aberdeen Centre. A pure growth of the organism was obtained from the foetal stomach contents. E coli has been reported as a cause of abortion in cattle. This unit reported three stillborn calves but only the above calf was submitted for examination.

Skin Disorders

Two skin tumours were examined at the Aberdeen Centre. Histopathological examination of a lesion on the hindleg of an 18-month-old stirk confirmed malignant melanoma. The carcass had been detained at the slaughterhouse pending the analysis.

In the second case a large (0.86 kg) mass removed from the left hind leg of a 30-month-old stirk at slaughter was confirmed as a benign dermal melanoma.

Musculoskeletal conditions

A five-month-old pyrexic calf which collapsed with poor muscle tone was shown to have low blood levels of glutathione peroxidase (GSH-PX) and vitamin E and dramatic elevation of creatinine phosphokinase (CPK) (85,000 iu/l, reference range <165iu/l). A diagnosis of nutritional myopathy (white muscle disease (WMD)) was made and five other calves in the group also had low blood selenium (GSH-Px) and Vitamin E levels. The farmer was aware of a selenium deficiency problem on his farm but WMD had not been diagnosed previously at this time of year.