Veterinary Services

Nutritional and metabolic disorders

Cobalt deficiency was diagnosed within a group of two and three-month-old Cheviot lambs on a unit in the Inverness area. Four deaths had occurred in a batch of 150 twin lambs, which were reported to be looking poor, despite anthelmintic treatment and trace element supplementation. Five of the six lambs were found to have sub-normal serum vitamin B12 levels, ranging from <74 pmol/l to 188 pmol/l (reference range 295-737 pmol/l). There was no evidence of concurrent parasitic gastroenteritis.

Chronic copper poisoning was confirmed by biochemical and histopathological analysis of liver and kidney tissues submitted to the Ayr Centre from a field necropsy. Unusually the affected animal was a castrated yearling Scottish Blackface - a breed considered to be less susceptible to the toxic effects of copper. The animal was at grass and no obvious source of copper could be identified. Another ten-week-old Scottish Blackface ram lamb was found dead on a holding in Inverness-shire, where a number of lamb losses had been reported. The carcass was jaundiced, the liver orange and friable and the kidneys almost black in colour. Although these findings were again suggestive of copper poisoning, the diagnosis could not be confirmed. Liver and kidney copper levels were found to be within reference ranges, and none of the typical changes of copper poisoning were noted on subsequent histopathology. The cause of the jaundice was not determined.

Generalised and systemic conditions

Septicaemia due to infection with Salmonella Dublin was confirmed in a two-year-old Texel ram found dead on an Aberdeenshire farm. Post mortem examination revealed evidence of an acute pneumonia and pleurisy.

Sudden death due to Mannheimia haemolytica septicaemia was diagnosed in a three-year-old Texel ewe. Necropsy findings included a swollen left mammary gland with cavitation, and associated enlargement of the supramammary lymph nodes. Fibrinous pneumonia with subpleural haemorrhages on the dorso-caudal lung lobes was also present. Mannheimia haemolytica was cultured in pure growth from mammary and lung lesions.

Alimentary tract disorders

A two-month-old lamb presented at the Thurso Centre for post mortem examination showed blood and froth at the mouth and further examination revealed an abscess in the pharynx. This lesion was suggestive of a dosing gun injury and Arcanobacterium pyogenes was subsequently cultured from the abscess.

Respiratory tract conditions

Pneumonic pasteurellosis due to Pasteurella trehalosi was confirmed as the cause of the death of a five-month-old Border Leicester ram lamb, being prepared for a show. Five lambs aged two months died on another small farm over the course of one week. The fifth carcass was presented for necropsy and Mannheimia haemolytica was cultured from pneumonic lesions.

A ten-week-old lamb was submitted to the Edinburgh Centre from a group of 50 housed orphan lambs on a diet of ad lib creep feed and silage. While in past years the orphan group on this farm has shown growth rates equivalent to the lambs at grass, this summer the housed lambs were as much as 20% lighter. In addition there had been three deaths within the group. The submitted lamb weighed 16kg and had extensive perineal soiling, sunken eyes and pale mucous membranes. The right anteroventral lung was consolidated and hepatised. The caecal mucosa was haemorrhagic, the colon slightly thickened and rectal contents bloody and fluid. Mycoplasma ovipneumoniae was isolated in heavy growth from affected lung tissue and histopathological changes of atypical pneumonia were reported. There was also evidence of coccidiosis on histopathology with secondary bacterial infection. Further investigation revealed no underlying vitamin B12, copper or selenium deficiency.

A two-year-old Scottish Blackface ram from a Borders farm died after being treated for pneumonia for a week. On necropsy an abscess was found at the thoracic inlet, organized unilateral pleurisy and associated lung consolidation. Arcanobacterium pyogenes was isolated from pneumonic lung and histopathology identified an underlying pulmonary adenocarcinoma.

Cardiovascular diseases

An adult mule ewe from a farm in Berwickshire was submitted for necropsy after dying suddenly, the fourth such death from a group of 1,100. Bodily condition was reasonable, but the carcass showed signs of left-sided heart failure with pleural effusion and marked pulmonary congestion and oedema. On examination of the heart chronic endocarditis was noted, affecting both aortic and left atrioventricular valves. Several cortical infarcts, ranging in diameter from 1 mm to 1 cm, were also noted in the kidneys. Histophilus somni (formerly Haemophilus somnus) was isolated from the heart lesions.

Mammary diseases

Staphylococcus aureus was isolated from a milk sample from a Dorset gimmer with mastitis.

Musculo-Skeletal conditions

Gangrenous cellulitis and toxaemia were diagnosed in a 12-week-old Scottish Blackface ewe lamb in the Edinburgh area. The animal had been seen lame with a swollen left hind limb. It had been given antibiotics, but had died the following day. At necropsy the left thigh was swollen and black, with some fleece loss over the medial aspect. Extensive gangrenous cellulitis covered the swollen area and extended along the left flank towards the thorax. Two deep puncture wounds were noted in the groin area, where the fleece had been forced into the muscle. However there were no wounds to suggest that this was a bite and the muscle was not significantly involved. Bacterial cultures from the site yielded a heavy mixed growth dominated by Proteus sp. and coliforms. Further enquiries revealed that the lamb had been caught on a fence a few days previously and this probably explained the puncture wounds.

Nervous system disorders

A recumbent lamb aged three months was submitted to the Ayr Centre for necropsy. A left submandibular lymph node abscess was present and associated cellulitis extended as far as the atlanto-occipital joint. Fusobacterium necrophorum was cultured from the lesions. A three-month-old Badger-faced lamb was submitted to the same Centre with a history of fitting, which occurred every two to three days. Brain histopathology revealed areas of the cerebellum where the Purkinje cells were absent or very small. This was believed most likely to be a congenital condition, possibly with a genetic aetiology.

A four-month-old Charollais cross lamb from a Berwickshire farm was found dead at grass. A general paleness and flattening of the gyri was noted on examination of the brain, which did not fluoresce under ultraviolet (UV) light. Subsequent histopathology identified changes consistent with a diagnosis of enterotoxaemia (pulpy kidney disease) caused by the epsilon toxin of Clostridium perfringens. Three days later an adult ram from the same unit was found in lateral recumbency, lacking a menace reflex but retaining spinal reflexes. Once again at necropsy marked swelling of the cerebral gyri was evident, but on this occasion some slight fluorescence was noted under UV light. Histopathology confirmed extensive necrosis in the cerebral cortex consistent with a diagnosis of CCN.

Skin diseases

Four cases of caseous lymphadenitis were reported around the country this month including two North Country Cheviot rams from a hill farm where the disease had not previously been recorded. On a number of occasions bacterial culture identified other skin pathogens when pus samples were submitted from sheep. Arcanobacterium pyogenes was isolated from an abscess in a three-year-old Scottish Blackface ewe. Arcanobacterium pyogenes and Pasteurella multocida were isolated from a discharging sinus behind the ear of a three-year-old Cheviot ram. Fusobacterium spp. was isolated from a large abscess on the jaw of a five-month-old Suffolk ram.

Psoroptes ovis mites were demonstrated in a fleece and scab sample from an upland flock in Perthshire where several animals were reported to be pruritic.