Veterinary Services

Toxic conditions
The accidental overdosing of a Texel ram with a copper supplement drench led to the animal's death some 36 hours later. The tup developed haemoglobinuria and jaundice prior to death and the diagnosis of toxicity was confirmed when liver copper was found to be three times the upper limit of normality (reference range 314 - 7,850 umol/kg).

Parasitic diseases
A three-year-old Suffolk ewe in poor body condition was submitted to the Ayr Disease Surveillance Centre (DSC) for necropsy. Gross findings of mucosal thickening and corrugation along the ileum were suggestive of Johne’s disease. However, histopathology provided no evidence of this condition and instead indicated that the problem had arisen from parasitic nematode infection. No parasites were detected at necropsy since the ewe had been treated with anthelmintic prior to submission, but given the site of the lesions and the time of year, infection by Trichostrongylus vitrinus was suspected.

Liver fluke damage and gastrointestinal nematode parasitism were associated with chronic ill-thrift in Soay lambs from an upland farm in Kincardineshire. This Soay breeding flock had been established one year previously, with ewes purchased from the south of Scotland. An 18-month-old Texel ram was submitted to the Edinburgh Centre for post mortem examination. This ram had been treated for laryngeal chondritis two weeks previously with some improvement, but had subsequently died. Examination confirmed laryngeal cartilage necrosis and oedema, with erosions at the tips of the arytenoid cartilages, which had led to an obstruction. However there was also evidence of chronic fasciolosis. Adult flukes were present in the bile ducts and adhesions of liver and lung to the diaphragm and the diaphragmatic muscle were consistent with aberrant fluke migration.

Acute and subacute fasciolosis was confirmed at the necropsy of housed hoggs from a unit in Argyll. This group of animals had been dosed for fluke using a triclabendazole product some six weeks previously, raising the possibility of anthelmintic resistance.

Generalised and systemic conditions
An adult ewe was submitted to the Edinburgh Centre for post mortem examination. This animal had reportedly appeared slow when the group was gathered for dipping and had subsequently been kept under observation on good pasture for two weeks before it died. Examination of the carcass revealed puncture wounds consistent with bites on the left hind limb and there was extensive necrosis and cellulitis here and along the ventral abdomen. A diagnosis of death secondary to cellulitis and toxaemia was made.

An eight-year-old Suffolk ewe in poor body condition was submitted to the Edinburgh Centre having died suddenly. On opening the carcass several litres of serosanguinous ascitic fluid were found. The liver was dramatically enlarged, with blood filled cavities in the parenchyma and a dark surface. The local lymph nodes, spleen and lungs showed similar changes. Histopathological examination of a range of tissues confirmed neoplasia, with microscopic findings suspicious of a carcinoid tumour. The primary neoplasm appeared to be in the lung, with vascular spread to the other organs. This is a rare tumour type of neuroendocrine tissue origin and efforts are continuing to confirm the diagnosis. A five-month-old lamb was found to have a chronic diaphragmatic hernia on post mortem examination at the Inverness Centre. Portions of the small intestine and caecum were found within the thorax, along with approximately half of the liver. The liver also appeared markedly pale and when trace element analysis was carried out, profound deficiencies of cobalt and selenium were identified - suggesting the possibility of ovine white liver disease in addition to the lesion in the diaphragm.

Alimentary tract disorders
Thirteen deaths occurred amongst a group of 310 Scottish Blackface lambs grazing a stubble field on a Perthshire farm. When one lamb was submitted for examination, undigested cereal grains were found within the rumen and the liquor pH was found to be 4, confirming the diagnosis of ruminal acidosis.

Respiratory tract conditions
A ten-month-old Texel ram lamb died on an Aberdeenshire farm after showing signs of coughing and dyspnoea. This animal was one of a small group of rams, from which another four-year-old animal had died some two weeks previously, also after showing severe respiratory distress. Laryngeal chondritis was confirmed on necropsy, along with a massive intrathoracic haemorrhage, which had resulted in the collapse of one lung. A six-month old Cheviot ewe lamb was submitted to the Dumfries Centre following several sudden deaths in the group. Necropsy identified a severe unilateral pyothorax, with 2.5 litres of pus recovered from the left side of the chest. Arcanobacterium pyogenes was isolated from the abscess and from other sites around the carcass.

An outbreak of coughing, dullness and deaths amongst a group of housed Scottish Blackface ram lambs was investigated at the Edinburgh Centre. A total of fourteen lambs were submitted for post mortem examination over a five-week period. Diagnoses of pneumonia due to Mannheimia haemolytica and systemic pasteurellosis due to Pasteurella trehalosi were made. There was also evidence of large burdens of the lungworm Dictyocaulus filaria in the lungs of many necropsied animals, and Mycoplasma ovipneumoniae was isolated on a number of occasions.

Reproductive tract conditions
An abortion occurred shortly after a group of seven in-lamb ewes arrived at a unit on the Shetland Isles. The cause of abortion was diagnosed as toxoplasmosis, with an assumption that the initial infection took place on the farm of origin and well before transit from the mainland. Although a ten-month-old Suffolk ram lamb had run with ten ewes on an Inverness-shire farm, none was found to be in-lamb when scanned. Two semen samples were collected from the ram by electroejaculation and although both were of good volume and colour, no sperm motility was noted. On subsequent examination of stained semen smears more than 95% of the sperm were found to have kinked or tightly coiled tails and many had detached heads.

Nervous system disorders
A recumbent six-month-old Scottish Blackface lamb showing signs of torticollis was submitted to the Dumfries Centre for necropsy. No significant gross abnormalities were detected post mortem and the brain did not fluoresce under ultra-violet light. However, histopathology confirmed severe and extensive lesions of cerebrocortical necrosis (CCN). A recently purchased, valuable Scottish Blackface shearling ram was found circling on an Inverness-shire farm. It was immediately treated with penicillin and vitamin B1, but died an hour later. On post mortem examination a pituitary abscess two centimetres in diameter was identified, from which a pure growth of Arcanobacterium pyogenes was isolated.

Skin diseases
Bovicola ovis lice were found to be the cause of pruritus in sheep from a small North Country Cheviot flock. The animals had previously been treated with an injectable avermectin product after the farmer incorrectly identified the condition as sheep scab.

Caseous lymphadenitis (CLA) was diagnosed in a Suffolk ram from a flock in the Western Isles. Three other recently purchased rams showed firm nodules below the ears and one had an abscess that was at the point of rupture. Another ram, purchased at the same time and now run with a neighbouring flock, also showed clinical signs suggestive of CLA infection.

Pus samples were submitted to the Ayr Centre as part of an investigation of CLA. Two recently purchased rams had developed abscesses during a period of on-farm quarantine. Actinobacillus lignieresi was isolated from a swab submitted from one tup with a neck abscess, while Staphylococcus aureus was isolated from the other Texel tup.