Veterinary Services

Nutritional and metabolic disorders

Pregnancy toxaemia was diagnosed on 14 occasions this month. In a case reported by Dumfries, blood samples were received from three downer ewes that were not responding to treatment. Serum beta-hydroxybutyrate levels of 9.1, 7.5 and 7.8 mmol/l (normal range <1.2mmol/l), confirmed the suspected diagnosis. In another case from Dumfries hypocalcaemia was diagnosed in three ewes that became recumbent one month pre-lambing. The calcium results were 0.7, 1.0 and 0.7 mmol/l, (normal range 2-3 mmol/l).

Toxic conditions

The second animal to die in a group of 100 Texel lambed gimmers (two-year-old ewes) was submitted to Edinburgh for necropsy. Both were purchased from the same source in December 2007. Other gimmers bought at the same time from a different source were well. Both gimmers produced healthy single lambs before becoming inappetant, dull and recumbent, and dying despite treatment with calcium and antibiotic. At necropsy the carcase appeared jaundiced and the liver was bronzed. Copper poisoning was confirmed by a liver copper content of 22,300 mmol/kg D.M., well above the upper reference limit of 7,850 mmol/kg. In view of the history, the SAC considered that the problem probably originated at the previous holding and advised alerting the previous owner to the findings.

Rhododendron poisoning was diagnosed in a group of Suffolk rams that escaped their paddock on a unit in Ross-shire. On presentation the rams were recumbent and showed signs of teeth grinding and regurgitation. Necropsy of one carcase confirmed the presence of large quantities of rhododendron leaves within the rumen contents. The rams had gained access through a broken fence to woodland that contained many wild rhododendron plants.

Parasitic diseases

SAC Centres recorded 115 incidents of chronic fasciolosis during the first three months of this year, compared to 42 in the same period in 2007. In contrast, only eight incidents of acute fasciolosis were diagnosed, compared to 11 in the first three months of 2007.

Chronic fasciolosis was the most frequent ovine diagnosis made at Ayr this month, affecting flocks in Ayrshire, Argyll and Renfrewshire. One affected flock reported 10 per cent mortality in hoggs and three per cent mortality in ewes, despite flukicide treatments in November and January. Severe hypochromic anaemia was evident in an affected ewe submitted alive for postmortem examination, which revealed evidence of acute and chronic fasciolosis compounded by chronic multifocal granulomatous interstitial pneumonia due to lungworm (Meullerius capillaris) infection. The SAC advised that animals were monitored post-flukicide treatment for evidence of anthelmintic resistance.

A carcase was received from a Dumfriesshire farm where the Scottish blackface ewes were losing condition. The carcase was emaciated, weighing only 31kg. Dermatophilosis lesions were noted affecting the nose, ears and lower legs. At necropsy there was evidence of hypoproteinaemia, with an increased volume of pericardial fluid. Although the ewe was not scouring, 740,000 mainly Teladorsagia worms were counted in the abomasum, and a further 84,000 Trichostrongyle sp. in the small intestine. Lungworm and large intestinal species were also numerous. The SAC advised that the level of infectivity within the fields grazed by the ewes would be high by mid-summer and therefore of risk to grazing lambs.

A ewe carcase was submitted from a farm where five of 15 pet sheep had aborted. Two had died and another two were reported to be unwell. The submitted carcase was thin and anaemic, and many flukes were present within the liver. It was later reported that although the rest of this flock had been treated for fluke in January, the small group of pet sheep had been missed.

Generalised and systemic conditions

Clostridial enterotoxaemia was diagnosed as the cause of the deaths of three of 190 fattening ewe hoggs on a holding in Dumfries-shire. One carcase was submitted for necropsy with a history of knuckling and nibbling at the ground, followed by recumbency and opisthotonus. On examination the kidneys were friable and there was excess pericardial fluid containing a chicken fat clot. The intestinal contents were positive for epsilon toxin and histopathology confirmed changes consistent with focal symmetrical encephalomalacia.

Alimentary tract disorders

The high cost of buying-in lambs for fostering was demonstrated when colisepticaemia due to infection with K99 positive E coli was confirmed in two neonatal crossbred lambs. The flock reported severe early onset scour affecting lambs from as early as 15 hours of age. Around 30 to 40 of the first 100 lambs born were affected. The flock had no history of a scour problem but two lambs were purchased for fostering 10 days previously.

Cryptosporidiosis and colisepticaemia were diagnosed in a lowground Ayrshire flock in lambs bottle-fed milk replacer. Cryptosporidiosis had been previously diagnosed in calves on the same farm.

Respiratory tract conditions

Septic pleurisy due to infection with Mannheimia haemolytica was the cause of death in a four-week-old Texel lamb in a pedigree flock in which four or five lamb deaths had occurred in one pen of 12 ewes and their lambs. In addition scabs from around the mouth were positive for parapox virus confirming orf.

Reproductive tract conditions

Multiple congenital defects were observed in a two-day-old Texel ewe lamb on an Aberdeenshire holding. These included inferior brachygnathism, unilateral renal hypoplasia of the left kidney (figure 4 - see top tight-hand side), hydronephrosis of the right kidney due to a blind-ending ureter with subsequent rupture of the ureter, and failure of complete development of the ileum leading to an intussusception. This was considered to be a sporadic case and not representative of the neonatal mortality problem on the unit.

A lowland flock of Cheviot-cross ewes experienced multiple late gestation abortions due to Pasteurella multocida infection. Pasteurella multocida is rarely associated with outbreaks of ovine abortion but it was isolated in profuse, pure growth from the stomach content of a single foetus and a set of twins. It was also isolated as part of a mixed growth from another single lamb and its placenta. Histology revealed suppurative placentitis in association with small Gram negative bacilli and suppurative inflammation in some sections of lung.

Mammary diseases

A three-year-old Texel ewe carcase was submitted for postmortem examination after a period of weight loss. Three abscesses were found in the right mammary gland, ranging from 3 to 6 mm in diameter. There was a profuse excess of clear peritoneal fluid and the liver was markedly enlarged with a nutmeg appearance. Approximately 98 per cent of the right lung was replaced by an abscess containing several litres of liquid and solid purulent exudate. Another small abscess was found in the wall of the left ventricle, measuring 2 mm in diameter. A diagnosis was made of primary mastitis and secondary pulmonary abscess with cor pulmonale. Staphylococcus aureus was isolated from the udder and Arcanobacterium pyogenes from both the lung abscess and the spleen. Although associated with the majority of noted lesions, the SAC considered that A pyogenes probably represented an opportunist infection.

Nervous system disorders

A ten-day-old Suffolk-cross lamb was euthanased and submitted to Edinburgh for necropsy with a history that it and ten other lambs had shown signs of hind limb ataxia from birth, but were otherwise thriving. The lamb was well grown and weighed 5.1 kg. Histological examination of the brain showed three localised perivascular glial foci within the cerebral cortex, suggestive of a protozoal infection. These findings were consistent with a non-fatal uterine infection with Toxoplasma gondii. Testing of the dams for evidence of Toxoplasma antibody was advised to confirm the diagnosis.

Skin diseases

Eleven cases of lice infestation were recorded, of which nine were reported in the area of northern Scotland served by Thurso.