Veterinary Services

Three Scottish blackface lambs died in a group of 280 following a move to winter grazing three weeks earlier. Others were lethargic and scouring despite the group receiving anthelmintic when they were moved.  Dumfries examined two carcases and found some anteroventral lung consolidation from which Mannheimia haemolytica was isolated.  The intestinal contents of one lamb were watery and there was evidence of a profuse scour.  Masses of worms were recovered from the intestine and the majority were Nematodirus battus, but trichostrongyle species were also present.  A mixed burden of 5,500 Teladorsagia and Trichostrongylus axei was recovered from the abomasum.  The faeces of the second lamb were normal and smaller numbers of worms were recovered.  The history in this case suggested that infection with Nematodirus had occurred following the move to wintering. 

Parasitism due to Chabertia ovina infection was diagnosed as the cause of poor bodily condition within a group of two-year-old Scottish blackface ewes.  One bright but emaciated ewe submitted for euthanasia and postmortem examination showed no body fat.  Small areas of the diaphragmatic lung lobes were consolidated and moderate numbers of lungworm were found within the bronchi.  Small numbers of adult fluke were found in the liver, the mesenteric lymph nodes were enlarged and the faeces were soft.  Large numbers of C. ovina worms were present in the colon and there was associated mucosal haemorrhage and thickening.  Following a gut wash 7,300 Teladorsagia circumcincta were recovered from the abomasum, with 2,075 mainly Nematodirus battus found in the small intestine.  Serum albumin was 16 g/l, (reference range 28-34 g/l) with a pepsinogen of 2.1 iu/l, (reference range <1 iu/l), and histopathology confirmed significant parasite damage in the colon. SAC C VS considered that local damage caused by the C. ovina worms was the main cause of protein loss, although fluke and Teladorsagia burdens would also have contributed.

Generalised and systemic conditions

The owner of a flock from central Aberdeenshire reported three deaths amongst a group of 119 Scottish blackface ewe lambs, purchased at market at the end of September. Two lambs were submitted for examination.  Septicaemia due to infection with Bibersteinia trehalosi was confirmed in one lamb, and pneumonia due to infection with Mannheimia haemolytica was confirmed in the second.  Both lambs had hepatic pathology suggestive of liver fluke infection and liver fluke eggs were detected in the faeces of each.  October tends to be the peak month for diagnoses of systemic B. trehalosi infections, although this year the monthly total of seven outbreaks was only half of the number for the same period in 2009.

Five deaths occurred in a group of 150 five-month-old lambs on a farm near Inverness, a week after they had been transported there for winter grazing.  One lamb was submitted for necropsy after showing respiratory signs prior to death. Gross findings were suggestive of septicaemia and Mannheimia haemolytica was isolated from the lungs. Despite the organism not being isolated from other tissues, histopathology was consistent with septicaemia being the cause of death.

Alimentary tract disorders

Between January and October 2010 there were 52 diagnoses of Johne’s disease in sheep in Scotland compared with 53 for the whole of 2009.  At St Boswells Johne’s disease was diagnosed in two greyface ewes with a history of chronic wasting over a period of a few months.  These were the only animals affected from a group of 180.  One carcase showed the typical gross findings of thickened, corrugated and yellow pigmented areas on the distal small intestine and a granulomatous lymphadenitis.  The disease was confirmed by the detection of typical clumps of acid-fast bacilli on a ZN stained smear. The pathological findings in the second animal were less distinct but histopathology of the small intestine revealed chronic enteritis with gross thickening and oedema, and infiltration by lymphocytes, plasma cells and eosinophils.  A granulomatous lymphadenitis was detected in histological sections of a mesenteric lymph node. These findings are consistent with the paucibacillary form of Johne’s disease in which the lymphocyte is the predominant cell type in the enteric inflammatory infiltrate and few, if any, mycobacteria are visible. 

The pigmented form of Johne’s disease was also diagnosed on gross postmortem examination of a very thin three-year-old Scottish blackface ewe submitted to Edinburgh from a traditional hill farm.   Diagnosis was confirmed on both serology and microscopy of a ZN stained ileal scraping.  In a third case, four of ten blood samples submitted from ill-thriven hill ewes on an estate in Perthshire were positive in the Johne’s disease ELISA test.

Renal diseases

Pyelonephritis and hydronephrosis were diagnosed in one of two Scottish blackface entire male lambs submitted to Ayr. Both lambs died within an hour of receiving an antibiotic treatment by subcutaneous injection.  This led the farmer to suspect toxicity.  However, on gross postmortem examination, both kidneys were markedly enlarged with dilated renal pelvises and purulent material in the medullary areas (Figure 1 - see top right-hand side).  SAC C VS considered that the pyelonephritis may have been secondary to an obstruction due to urinary calculi.  However the hydronephrosis could have followed an obstruction caused by purulent material from the pyelonephritis. 

Skin diseases

 
Pruritis due to Psoroptes ovis infection was diagnosed on an Ayrshire farm.  Samples were submitted on three occasions before mites were detected.  Subsequent discussions with neighbours found that three adjacent holdings had treated sheep for pruritis recently without veterinary involvement.  Psoroptes ovis mites were detected in a wool sample from a pruritic ram submitted to Dumfries.  The group to which this animal belonged was treated for suspected lice the previous week with no improvement.