Veterinary Services

Nutritional and metabolic disorders

The Inverness Centre received a portion of liver from the jaundiced carcass of a Cheviot gimmer. The liver tissue was pale and friable, and the level of vitamin B12 was <0.07ug/g wet weight, indicative of severe vitamin B12 deficiency. The liver pathology was consistent with ovine white liver disease, although confirmation of this diagnosis requires the identification of characteristic histopathological lesions.

Toxic conditions

Seven Texel lambs from a group of 52 were reported to have died over a period of two days. Death had been preceded by a short spell of dullness, anorexia and apparent discomfort. In addition, some lambs were seen to produce reddish brown urine. This group had been concentrates ad-libitum until one week earlier, when they had been moved to poorer pasture and restricted to daily ration of 1-1.5kg/head. Two carcasses were submitted to the Dumfries Centre and were found to be jaundiced, with orange coloured livers, black kidneys and evidence of haemoglobinuria. The liver copper levels were respectively 23,900 and 25,900 umol/kg (reference range 314 - 7,850 umol/kg) and kidney copper 1,190 and 1,750 umol/kg. (reference range <787umol/kg). On the day that the carcasses were examined the remaining 45 lambs were delivered to an abattoir, where they were held at grass over a weekend. During this period a further four animals died. Following the slaughter of the remaining lambs, 13 carcasses were condemned at meat inspection because of jaundice. Examination of the concentrate fed to the lambs revealed that it contained a mineral inclusion intended for cattle. In addition, the lambs had been drenched monthly with a copper and cobalt supplement - a frequency far in excess of that recommended by the manufacturer. This incident was reported to the Food Standards Agency as a potential food safety incident.

Generalised and systemic conditions

A five-year-old, in-lamb ewe was found dead on an Aberdeenshire unit. Following necropsy Mannheimia haemolytica was isolated from the lung and kidney, and Pasteurella trehalosi was isolated from the uterus. Septicaemic pasteurellosis due to infection with M. haemolytica was also confirmed in a second ewe submitted from the same unit the following day.

Alimentary tract disorders

Seven Scottish Blackface ewes from a flock of 1,100 were found dead, and others were said to be anorexic and depressed. When a carcass was submitted to the Dumfries Centre a solid column of dry beet pulp was found to fill the oesophagus from the larynx to the diaphragm, distending it a diameter of 5cm. In addition there were other lesions suggestive of an infectious process, and Pasteurella trehalosi was subsequently cultured from the carcass in a systemic distribution.

Scouring and ten deaths were reported in a group of 200 lambs on an Aberdeenshire unit. The losses had occurred in the month following the introduction of a new diet of turnips, concentrate pellets and barley. When a carcass was submitted for examination the rumen contained a large volume of grain and pale wet ingesta, and the pH of the rumen liquor was found to be 3.5, confirming a diagnosis of carbohydrate overload and acidosis.

Intestinal obstruction secondary to omphalitis and urachitis was confirmed in a six-day-old lamb that died following a clinical history of abdominal distension. Omphalophlebitis and hepatic abscessation were confirmed at post mortem examination of another three-week-old Suffolk lamb. The owner also reported a significant scour problem amongst the neonatal lambs, and there was evidence of enteritis and severe dehydration on examination of the submitted carcass. Subsequent examination of intestinal contents confirmed very large numbers of cryptosporidial oocysts.

A Scottish Greyface gimmer was submitted to the Edinburgh Centre for post mortem examination, the second animal to die within a group being fed big bale haylage and silage. On necropsy the abomasum was distended with watery haemorrhagic content and had a diffusely congested and thickened mucosa (Figure 1; click on link in right hand column). The abomasal mucosa showed diffuse multifocal erosions and ulceration, and there was also evidence of a mild colitis. Listeria monocytogenes was isolated from the abomasal mucosa, along with other commensal organisms. The above presentation is a recognised form of listeriosis, which in common with other forms of the disease is often identified in animals receiving a silage-based diet.

Reproductive tract conditions

Dystocia was diagnosed when two large twin lambs were submitted for necropsy with a history of respiratory distress and death within minutes of birth. There was evidence of haemothorax in one lamb and haemoperitoneum in the other.

A Scottish Bluefaced Leicester gimmer was submitted alive to the Dumfries Centre with a history of weight loss. An abscess 20cm in diameter was identified at the cervical end of the uterus, which contained copious dark, foetid fluid. Further examination revealed the presence of a retained vaginal sponge and it was suggested that this had predisposed to the metritis.

Abortion due to Salmonella Montevideo was confirmed on submission of a foetus and placenta from a pedigree Suffolk ewe. The flock of 60 ewes had already received this diagnosis some three weeks earlier, after several other abortions were investigated. In this case the aborted fetus showed petechiae on pleura, epicardium and peritoneum, and the liver capsule had ruptured. The placenta was congested and thickened, and was coated with a necrotic discharge. S. Montevideo was isolated from foetal stomach contents and placenta.

The carcass of a five-year-old Suffolk ewe was submitted following abortion and subsequent death, four weeks prior to the due date. The ewe had marked vulval and perineal swelling, and congested mucous membranes. The carcase appeared toxaemic with macerated foetuses in-utero. Placenta and uterus were a dark wine coloured. Culture of uterus and placenta isolated Clostridium sordellii, which is a recognised cause of toxic metritis in ewes.

Three Suffolk flocks in the area served by Thurso DSC reported severe subcutaneous oedema prior to lambing. This oedema was apparent in the perineal area, but in severe cases extended to the udder, hind legs and abdomen (see Figure 2; click on link in right hand column). In most cases the affected ewes remained clinically normal in all other respects, until such time as parturition commenced, typically seven to ten days prematurely. Several ewes developed a fatal metritis and septicaemia following lambing, while others required a caesarean section from which they failed to recover. In the worst affected flock, approximately half of the 60 ewes developed the condition, with twelve of these showing severe swelling. The majority of the worst affected ewes went on to die, while lambs from another ten ewes did not survive parturition. In the other two flocks with a similar condition, the number of affected ewes remained in single figures. Interestingly, ewes of other breeds on the affected farms did not show clinical signs, with the only difference in management being that the Suffolk ewes were more heavily fed.

Initial investigations have failed to identify a likely bacterial or viral pathogen, and blood biochemistry findings in the affected ewes showed no consistent abnormalities. The theory of an underlying mycotoxicosis is now being explored and further investigation of the feed offered to the affected ewes is now in progress.

Nervous system disorders

An outbreak of infectious keratoconjunctivitis in a Cheviot flock was investigated by staff at the Dumfries Centre. The condition was first recorded in November, appearing in a ram that had run with two purchased animals. It was suspected that one of these bought-in rams had acted as a sub-clinical carrier of infection. Since then, some 60% of the sheep in a flock of 500 Cheviots have required topical or systemic antibiotic treatment for the condition. Bacterial culture of ocular swabs from affected but untreated sheep produced a growth of both Mycoplasma conjunctivae and Branhamella ovis.

Skin diseases

A crofter reported a severe skin condition of sheep on common grazings in the West Highlands. Around one third of his 75 ewes were affected, the main feature of the condition being scabs on the pinnae, with no swelling or pruritis. In chronic cases one or both pinnae became necrotic and were lost completely, with affected ewes also appearing to lose condition. The first case occurred in spring 2005 and more animals were affected at the beginning of January this year. Interestingly, other sheep on the same common grazing were said to remain unaffected. On submission of skin scrapes there was found to be no evidence of ectoparasites, Dermatophilus or ringworm. Photosensitization was felt to be unlikely, since the condition occurred during the winter and spring. Staphylococcus aureus was isolated in culture from the ear of one animal. On histopathology there was evidence of bacterial dermatitis, but also of eosinophils, suggesting a possible immune-mediated or parasite-induced reaction. Investigations continue.