Veterinary Services

Toxic conditions

Several gimmer replacements from a Lleyn flock in the Scottish Borders were reported to have shown signs of anorexia over a period of a week. When one of the affected sheep died the carcass was necropsied and found to be jaundiced, with a bronze coloured liver and dark, swollen kidneys. Tissue analysis for copper confirmed a level of 41,900 µmol/kg within the liver (reference range 314 - 7,850) and 2,940 µmol/kg in the kidney (reference range < 787). The urgent removal and re-assessment of the home-mixed concentrate ration was advised.

Parasitic diseases

Parasitic gastro-enteritis was diagnosed in two crossbred lambs submitted to the Edinburgh Centre for necropsy. There had been seven deaths in a group of 327 lambs over a two-week period. Both carcasses submitted were thin and had extensive faecal soiling of tail and perineum. Total worm counts on small intestinal washings from one of the lambs identified the presence of 19,000 Nematodirus battus adults and larvae. The lambs had been dosed with anthelmintic four weeks earlier and moved onto silage aftermath. The possibility of anthelmintic resistance was raised and post-drench efficacy checks were advised. However no further faecal samples have yet been submitted for examination.

Parasitic enteritis due to Trichostrongylus colubriformis and T. vitrinus was confirmed at the Ayr Centre in a six-month-old crossbred lamb from a group of 200. Two deaths had occurred and other lambs had scoured for several weeks, despite treatment with levamisole. Although additional faeces samples were requested to enable a check of levamisole efficacy once again none has yet been received. Three groups of 10 lambs on another local unit were subjected to a dose-response trial using an anthelmintic from each class. Benzimidazole resistance was detected but avermectin and levamisole appeared effective.

A two-year-old Scottish Mule ewe was presented at the Edinburgh Centre for necropsy following a short period of depression, hind limb weakness and apparent neurological signs. Another four deaths had been reported in this group of 140 ewes, which had received a levamisole and triclabendazole drench after lambing and reportedly grazed good pasture all summer. At necropsy a fibrinous peritonitis was present with approximately two litres of serosanguinous fluid present in the abdomen. The liver was enlarged and discoloured, with a rough capsule and many immature flukes were present in the parenchyma. On this basis a diagnosis of acute fasciolosis was made. Acute fasciolosis was also diagnosed at the Thurso Centre after the death of 10 sheep in a flock of 200, over the course of a week.

Generalised and systemic conditions

Systemic pasteurellosis was diagnosed in two, five-month-old Scottish Blackface lambs from a Perthshire hill flock where thirteen lambs had died from a group of 400. At the Thurso Centre the same diagnosis was made in an outbreak in which 22 unvaccinated lambs had died from a group of 800 in the two weeks following weaning.

Alimentary tract disorders

Intestinal haemorrhage syndrome (redgut) associated with torsion of the intestine around the root of the mesentery was confirmed in a Suffolk lamb found dead. A total of eight deaths were reported in the affected group of 72 lambs, moved on to recently sown, lush pasture after weaning.

Three ewes were submitted from an Aberdeenshire unit where multiple cases of ill-thrift amongst adult ewes and rams had been recorded over the last two years. The ewes showed evidence of parasitic gastroenteritis and parasitic pneumonia, and histopathological examination of the intestine confirmed paucibacillary paratuberculosis (Johne's disease).

Respiratory tract conditions

Ovine pulmonary adenocarcinoma (OPA) was diagnosed in a North Country Cheviot gimmer from a flock in Ross-shire, which showed signs of ill-thrift and a persistent cough. The affected animal was one of seven gimmers that had been recently purchased.

Musculo-Skeletal conditions

A two-year-old Texel ewe was reported to have developed difficulty in standing and pain in the lumbar region. Over the course of two weeks this progressed to a swelling of multiple joints, which responded only transiently to antibiotic and anti-inflammatory treatment. At necropsy all of the limb joints except the hips, contained an excessive quantity of pale green/grey synovial fluid. There was no evidence of involvement of the vertebral column. A profuse growth of Streptococcus dysgalactiae was isolated from bacterial culture of the affected joints. A sparse growth of the same organism was isolated from the liver. This is an unusual presentation of a condition that has been recorded very frequently amongst neonatal lambs during 2005 (SAC Monthly Reports, March and April, 2005)

Nervous system disorders

Louping-ill was diagnosed in Scotland on seven occasions during the month of September. A six-month-old Scottish Mule lamb from a flock in Inverness-shire presented with tremor, polyarthritis and malaise. The animal was found to be pyrexic and a blood sample was found to have a louping-ill antibody titre of 1/40,960. Much of this antibody was identified as IgM, consistent with the animal having been recently infected. Louping-ill was also diagnosed in a five- month-old Cheviot ewe lamb, one of a batch of 140 that had been purchased the previous week. Three deaths had been reported in this group since arrival on the new holding, also in Inverness-shire.

Border disease in sheep is caused by a pestivirus (border disease virus or BDV) closely related to bovine virus diarrhoea virus (BVDV) in cattle. The similarity between these viruses is so great, that it is estimated that 15-20% of the outbreaks identified as Border disease in UK sheep are in reality caused by BVDV-1. Despite this, a clear connection between BVD-infected cattle and BD affected sheep can be difficult to establish.

Earlier this year (SAC Monthly Report, May 2005) we reported the investigation of an outbreak of Border disease in a Scottish Blackface flock in Perthshire which followed the diagnosis of mucosal disease amongst heifers on the same farm. During the autumn of 2004, one particular group of pregnant ewes had grazed in the same field as the heifers in question. Some of the lambs born to these ewes were then found to show neuropathological lesions consistent with Border disease - with lambs from other groups on the farm unaffected. The virus recovered from both the affected sheep and the cattle has now been identified as BVDV-1. In addition, the 44 remaining lambs produced by these particular ewes have now been blood sampled at six-months of age. A total of 23 lambs were found to have detectable antibodies to pestivirus. The remaining 21 had either little or no antibody titre, and of these eight of the poorer lambs were shown to be positive for BVDV-1 virus in a polymerase chain reaction (PCR). Additional sequencing work is now proceeding to confirm that the virus from the sheep and the cattle is indeed identical.

Skin diseases

A five-year-old Cheviot ewe from a flock on the Isle of Skye was submitted to the Inverness Centre with bilateral skin erosions midway between the eyes and the nostrils and deep enough to reveal the underlying nasal turbinates. Another two ewes in the flock were reported to be showing similar, but less severe lesions. The submitted ewe was in very good bodily condition and no other gross abnormalities were detected. Pseudomonas aeruginosa and Fusobacterium necrophorum were isolated on bacterial culture of the scabbed nasal lesions and no additional contributory factor could be identified.