Veterinary Services

Severe cobalt deficiency (pine) was confirmed in two four-week-old lambs submitted from a large sheep flock in Aberdeenshire where ill thrift and a grey coat colour were noted. There was concurrent coccidiosis in one of the submitted lambs and both were developing nephrosis.

White muscle disease was confirmed on histopathological examination of the heart from a six-week-old Berrichon lamb submitted to Dumfries after the animal collapsed and died.

Toxic conditions

Ayr confirmed copper poisoning in shearling blue-faced Leicester rams. Three of the 19 animals in the group died over a week. The liver and kidney copper contents were 13,100 µmol/kg and 2,940 µmol/kg respectively (reference ranges 314 - 7,850 µmol/kg and <787 µmol/kg).

Parasitic diseases

The owner of an Aberdeenshire flock reported carcase detention and condemnations resulting from the presence of Cysticercus ovis cysts in the musculature of hoggetts from three batches submitted to an abattoir in the preceding weeks. The hoggetts had remained at grass since purchase during November and December 2006. A home-mixed concentrate of oats, beans and soya was fed since early April. Whilst concern was expressed over the possible involvement of foxes in the spread of infection, the SAC also noted that the farm dog was not regularly treated for tapeworm infection and could have had access to the feed store.

Nematodiriasis was diagnosed on 29 occasions during the month, a figure considerably lower than the 91 outbreaks recorded during June last year and the average for the last five years of 55 outbreaks. This implies that the weather conditions were not conducive to a mass hatch in June. In a case reported by Ayr, four out of 40 three-months-old lambs developed diarrhoea and died within seven days. The diagnosis was made on postmortem examination, with many adult worms and larvae demonstrated in washings from the digestive tract. Significantly, no Nematodirus species eggs were present in the faeces of the submitted lamb, indicating that this fatal infection was still in the pre-patent phase. This is not unusual in cases of death due to nematodiriasis and emphasises the importance of carrying out necropsies when unexplained deaths occur amongst grazing lambs.

Chronic fasciolosis was determined to be the cause of death in a four-year-old Lleyn ewe submitted to Edinburgh. Large numbers of mature fluke were found in the bile ducts, and hepatic fibrosis was evident.

Generalised and systemic conditions

Four lambs were submitted for necropsy from a small bluefaced Leicester flock near Edinburgh. Two lambs were diagnosed as suffering from systemic pasteurellosis due to Bibersteinia (Pasteurella) trehalosi. A third showed meningitis from which B. trehalosi was also isolated. Concurrent coccidiosis and selenium deficiency were found to be contributing factors in one of these lambs.

Alimentary tract disorders

Johne’s disease was diagnosed on postmortem examination of a four-year-old Hebridean ewe from the Uists. This animal was one of several ewes to have lost condition and died despite retaining appetite. Although autolysis masked any possible gross lesions, ZN-stained smears from the small intestine were positive for acid-fast organisms resembling Mycobacterium avium subsp. paratuberculosis and a diagnosis of Johne’s disease was confirmed on histopathological examination.

Nervous system disorders

Louping ill was identified as the cause of death in an eight-week-old lamb euthanased after developing nervous signs unresponsive to treatment. Unusually, this case occurred in an area served by Edinburgh where tick-borne diseases are uncommon.

Louping ill was also confirmed in a lamb from a farm in Inverness-shire where several ewes and lambs had died on hill pasture. Louping ill was confirmed in this case by neuropathology and serology, which indicated recent infection. After an earlier diagnosis of louping ill, hoggs on this holding had been vaccinated against the disease and it was noteworthy that no deaths had occurred within this age group on this occasion.

Renal diseases

Renal failure was the cause of death in an eight-week-old lamb on an upland farm. Nervous signs attributable to uraemia had been observed pre-mortem and on postmortem examination the kidneys were found to be pale, swollen and discoloured. Histopathology of the intestine and kidneys confirmed the diagnosis of nephrosis secondary to nematodiriasis.

Skin diseases

A well-grown ram lamb was found dead with evidence of a swollen head due to extensive subcutaneous bloodstained oedema. Clostridium sordellii was isolated from these affected areas, although not from liver, spleen or kidney. The SAC speculated that this case was initiated by a head injury sustained during fighting within the group.

The carcase of a Scottish blackface ewe was examined as part of a welfare investigation. The ewe was in good condition and the carcase was very fresh. There was a significant area of blowfly strike affecting the tail, perineum and upper left hind leg. Maggots were also present on the right hind foot, which was affected with footrot. The faeces were soft and the gut worm egg count was 10,400 eggs/g. The SAC considered that parasitism had predisposed to the perineal strike, while the presence of footrot lesions attracted flies to that foot.

Caseous lymphadenitis (CLA) was diagnosed in five ewes from a flock in Ross-shire showing abscesses of the parotid, submandibular and prescapular lymph nodes. The farm had a history of CLA and approximately five per cent of the ewes have superficial abscesses. Arcanobacterium pyogenes was isolated from a sixth case on the same farm. A combination of regular clinical inspection and four-monthly screening of all adult animals using the CLA ELISA test has now been proposed in an effort to eradicate the disease from this flock.

In June, CLA was diagnosed in seven flocks in the north of Scotland; the highest monthly total recorded at Thurso DSC. In most cases the pedigree animals affected had been brought into the area during the autumn of 2006.