Veterinary Services

Four lambs from a group of 195 on a holding near Dumfries died over a period of 24 hours.  All were in good bodily condition and were moved on to fresh grass some five days earlier. In one carcase examined, the myocardium was mottled on cross-section (figure 4 - see top right-hand side) and nutritional myopathy was confirmed by histopathology.  The liver selenium levels of the two lambs were deficient at 0.25 and 0.36 mg/kg dry matter (DM) respectively (reference range 0.9 – 3.5 mg/kg DM). Tissue vitamin E levels were within the normal range. 

On another farm, ten lambs died over 24 hours, three days after housing.  One carcase submitted for postmortem examination showed acute pulmonary congestion and paleness of the liver.  A large quantity of whole barley grains was present in the rumen. The Rumen pH of 4.6 was consistent with a diagnosis of acidosis secondary due to grain overload.

Parasitic diseases

Chronic fasciolosis was diagnosed in flocks from Argyllshire, Ayrshire and Dunbartonshire.  In two flocks flukicide resistance was suspected following the identification of Fasciola hepatica eggs in faecal samples taken three weeks post-treatment. The veterinary surgeons involved were advised to inform the Veterinary Medicines Directorate and the manufacturer, and to use an alternative product.  Continued monitoring of the flocks by examination of faecal samples for F. hepatica eggs and blood samples for liver enzyme levels from any animals in poor condition was also advised.

Parasitic gastroenteritis (PGE) was diagnosed in a Stirlingshire flock in which four lambs were found dead over a period of two weeks.  All were in good condition but  showed sudden onset diarrhoea.   A pooled faecal sample revealed a worm egg count of 3,900 trichostrongylid eggs per gram. The group were wormed seven weeks previously.  Advice was given on screening for possible anthelmintic resistance.

PGE was also confirmed in three live lambs and one dead lamb submitted to Aberdeen. The history was of a failure to thrive, with few lambs reaching slaughter weight.  Fifteen lambs died in the group of 650. They were treated with an avermectin at weaning in July and with a levamisole drench at the end of September.  All four of the submitted lambs were found to be in very poor body condition.  In addition to PGE there was evidence of copper and selenium deficiency.

Generalised and systemic conditions

Black disease was suspected in a four-year-old Texel-cross Cheviot ewe found dead.  The owner reported a further ten deaths in the flock of 160, moved on to the grazing at the beginning of November.  In most cases the affected ewes were in good bodily condition.  At postmortem examination of the submitted carcase the liver was irregular, with black areas on the sub-capsular surface and within the parenchyma.  Adult liver flukes were present in the bile ducts.  The pericardium contained a large volume of blood-stained fluid and a fibrin clot.  Anaerobic culture of the liver yielded a Clostridium species, although this could not be further identified. 

Only six new cases of systemic pasteurellosis were diagnosed during November.  The months of October and November are when the majority of such outbreaks, caused by Bibersteinia (Pasteurella) trehalosi, are diagnosed in Scotland.  During October and November 2008 only ten outbreaks were reported by SAC.  This compares with 33 outbreaks recorded over the same period in 2007 and 72 outbreaks in 2006.

Alimentary tract disorders

A seven–month-old Scottish blackface lamb was submitted live to Dumfries for post-mortem examination. Four others in the same group died with swellings under the chin and blood clots within their mouths.  Similar findings were recorded in the submitted live lamb, which was also very anaemic on clinical examination.  Following euthanasia the swelling between the mandibles was found to consist of blood clots, fibrous tissue and necrotic tissue.  Fusobacterium necrophorum was subsequently isolated in mixed culture from the area.  An underlying dosing gun injury was suspected. 

On a second farm, eight of 125 ewes died over a period of two weeks.  Some were recorded as sudden deaths, with the carcases showing blood at the nostrils.  Other ewes lost condition after becoming anorexic before death. Trace element boluses were administered to the group some three weeks earlier.  A carcase submitted for necropsy had a fistula in the pharynx. This contained the remains of a bolus.  There was little evidence of damage or infection in the surrounding tissues but SAC considered that the lesion would have prevented the ewe from eating normally.

Respiratory tract conditions

Ovine pulmonary adenocarcinoma (OPA) or jaagsiekte was diagnosed in a four-year-old ewe from an Argyllshire flock with a history of ewe deaths during the preceding six months.  Viscera, submitted for examination after the ewe was found dead following a vague illness, showed pathognomonic histopathological lung changes.

Skin diseases

 
Arcanobacterium pyogenes and Staphylococcus aureus infections were diagnosed in bluefaced Leicester and Scottish blackface rams respectively in two Argyllshire flocks. In the first case chronic abscessation was present along the midline of the back and in the second an abscess at the angle of the jaw.  Bacteriology and serological screening of any similar cases for evidence of caseous lymphadenitis (CLA) was recommended.