Veterinary Services

With the return of severe winter weather to much of Scotland during February, there was widespread concern that many ewes were approaching lambing in a nutritionally compromised state.  In view of these exceptional conditions SAC C VS offered discounted blood tests to producers as an early warning of metabolic disease.  In addition to this monitoring work, clinical pregnancy toxaemia was also confirmed in ten different flocks during the month.  On a Lanarkshire farm two ewes in late pregnancy and described as lethargic and depressed died within ten days of each other. This was despite treatment with injectable calcium and glucose, oral liquid therapy and an antibacterial. The diagnosis of pregnancy toxaemia was made on the basis of the clinical history and gross pathology of an affected ewe and elevation of the beta-hydroxybutyrate (BOHB) level in vitreous humour. On other affected farms in Ayrshire the diagnosis was made on the basis of clinical signs and blood biochemistry on samples received from affected ewes three weeks before lambing.  Advice was provided on nutrition of the pregnant ewe. 

Three lambs were submitted to Dumfries from a farm where neonatal losses were considered to be too high.  The flock was also known to have a problem with thin ewes and pregnancy toxaemia.  In each case the cardiac and renal brown fat had been metabolised and the abomasum was empty.  Meconium was still present in two of the lambs.   Serum zinc sulphate turbidity values were measured at between zero and one unit (normal range > 14). This confirmed complete failure of colostral immunoglobulin absorption.  A diagnosis of starvation/hypothermia probably relating to poor ewe milk supply was made.

Toxic conditions

 
A three-year-old ewe was submitted to Inverness with reported neurological signs. Three other ewes died over a period of one month.  Gross findings were consistent with poor food intake and a large number of leaf fragments identified as Rhododendron ponticum were found within the rumen. Histopathology indicated hepatic lesions supporting the suspicion of intoxication. Probably the extreme weather and prolonged snow-covered pastures had led to indiscriminate grazing.

Parasitic diseases

Fasciolosis was once again the commonest diagnosis for Scottish ovine submissions. Chronic fasciolosis was reported in 38 flocks and acute disease in a further six.  In an Argyllshire flock chronic fasciolosis along with parasitic bronchitis due to Dictyocaulus filaria, caused losses in finishing Scottish mule hoggs.  This was despite a flukicide treatment in January, prompting an investigation of possible flukicide inefficacy.  A failure of efficacy in the use of triclabendazole was confirmed in another Argyllshire farm on the basis of the continuing presence of F. hepatica eggs in faecal samples taken three weeks post-dosing.

Cryptosporidiosis was associated with diarrhoea and deaths in five and ten-day-old lambs in Ayrshire, Argyllshire and Perthshire flocks. In the former, deaths were predisposed by hypogammaglobulinaemia and secondary colisepticaemia was apparent.

Generalised and systemic conditions

Clostridium perfringens type D disease (pulpy kidney) was diagnosed in a ten-month-old Texel cross hogg found dead on an Aberdeenshire unit.  Some 15 such deaths were reported over a three week period, affecting a batch of lambs purchased in autumn 2009. The group received only the first dose of a multivalent clostridial vaccine the previous week.

Reproductive tract conditions

Six abortions occurred over three days in a commercial Ayrshire flock, some five days before lambing was due to start and despite prophylactic treatment with an antibacterial product. Inclusion bodies typical of Chlamydophila sp were seen on placental and foetal stomach content smears providing a diagnosis of foetopathy due to Chlamydophila abortus.

Toxoplasmosis was diagnosed in an Ayrshire flock in which ten abortions occurred over three to four weeks. Affected ewes were unvaccinated against abortion and the material submitted included a mummified foetus. Histopathological changes evident in necrotic placental cotyledons and foetal serology confirmed the diagnosis. 
Foetopathy due to Bacillus licheniformis was diagnosed in an Ayrshire flock in which three sets of twins were aborted at varying stages of gestation, over a one month period.   

Listeriosis was diagnosed on three farms in the Dumfries area when Listeria monocytogenes was recovered from placenta and foetal stomach contents of aborted lambs.   On one of the affected farms listerial abortion was diagnosed in both ewes and ewe hoggs, despite them being kept separately and neither group being fed silage. 
Abortion due to Campylobacter fetus subsp. fetus infection was the most common diagnosis at Perth during February.  The most common clinical history was of abortions occurring in the two weeks prior to the expected start of lambing.

Nervous system disorders

Six deaths occurred in a group of nine-month-old purchased Scottish blackface hoggs during a period of eight days. Affected animals were reported to have an acute onset illness with blindness. Clinical examination of an affected animal in lateral recumbency revealed pyrexia, hyperaesthesia, paddling of legs and bruxism. Neuropathology revealed severe non-suppurative encephalitis centred on the pons, mid- and hind-brain, consistent with infection with Listeria monocytogenes. This out-wintered group were fed silage during a period of heavy snow.

Renal diseases

Urolithiasis caused by an accumulation of triple phosphate calculi was diagnosed in an eight-month-old Charollais cross Texel lamb. The lambs were fed a coarse mix ad lib from a feeder. Advice on ration analysis and the provision of adequate water was given.

Skin diseases

 
Insect larvae were submitted after being found during the inspection of an ovine carcase at the Isle of Lewis slaughterhouse. The larvae were located in the subcutaneous tissue over the thorax and were associated with numerous "breathe holes" penetrating through the skin and with substantial associated bruising.  Despite the atypical host, the larvae were identified by the Natural History Museum as most likely those of the roe deer warble fly Hypoderma diana.  There is one other report of H. diana affecting sheep from SAC C VS Inverness in 1983.