Veterinary Services

The owner of a hill farm, with 600 finishing lambs spread over several different fields, noted around 30 lean individuals, several of which appeared lethargic.  A live seven-month-old Lleyn ewe lamb was submitted to Edinburgh for postmortem examination.  The lamb was bright and ambulatory although lean.  A crusty dermatitis was noted on the ears.  At necropsy the only gross abnormality was a strikingly pale liver.  Liver selenium and cobalt concentrations were respectively 0.14 mg/kg DM (reference range >0.90 mg/kg DM) and 0.04 mg/kg DM (reference range >0.06 mg/kg DM).  Histopathology showed scattered, swollen eosinophilic muscle fibres consistent with white muscle disease and liver changes consistent with ovine white liver disease due to cobalt deficiency. SAC C VS considered the skin lesions were consistent with photosensitization, secondary to the liver pathology.

Parasitic diseases

Parasitic gastroenteritis (PGE) was confirmed by all centres this month.  A seven-month-old lamb was submitted from a farm in Ayrshire having shown ill thrift and scour prior to death.  A total worm count was carried out which yielded 5,400 worms in the small intestine, with Nematodirus battus being identified. In recent years there have been reports of autumn outbreaks of nematodirosis.

The carcase of a Texel cross hogg was submitted to Dumfries for postmortem examination after five from the batch died in a week.  The group were previously dosed with a moxidectin/triclabendazole drench and were grazing on a dairy farm for three weeks.  A severe scour was evident when the carcase was examined and more than 30,000 Trichostrongylus species worms were recovered from the intestines.  Re-infection following treatment was considered to be a possible explanation.

Patent Fasciola hepatica infection was diagnosed in 16 flocks this month compared with 32 in November 2009. Triclabendazole resistance was suspected in two flocks in the Ayr region, based upon the presence of fluke eggs in faecal samples taken in the period 21 to 28 days post-drenching.

Alimentary tract disorders

A three-year-old Texel cross ewe with weight loss and scour was seropositive for Johne’s disease.  Two goats which were subjected to pre-movement testing also tested seropositive for Johne’s disease.

A ten-year-old goat was submitted to Inverness for necropsy following pyrexia, inappetence and diarrhoea of a few days duration.  At necropsy a large amount of plastic and foil was found in the rumen (Figure 3 - please see top right-hand side) and there was evidence of proximal enteritis and PGE.  Subsequent histopathology detected fatty change in the liver consistent with a period of inappetence following intestinal obstruction due to a foreign body.

Nervous system disorders

The second of two Beltex rams to die within a week was submitted for postmortem examination.  Clinically it was described as leaning and circling, before rapidly deteriorating and dying.  The left hind foot was swollen with an abscess in the first interphalyngeal joint from which Arcanobacterium pyogenes was isolated.  Multiple tiny white lesions were found throughout both kidneys and there was a lesion on the left atrioventricular valve.  Staphylococcus aureus was isolated in pure culture from the brain, lung and heart valve.  Histopathology revealed micro-abscesses throughout the brain indicating a severe, multifocal, purulent meningoencephalitis and suggesting haematogenous spread of the causal bacteria.

Skin diseases

 
Numerous Damalinia ovis lice were observed in a wool sample submitted to Aberdeen from a group of pruritic Welsh mountain sheep.  Samples were submitted to Dumfries after scabs developed on the ears of a small group of Zwartables ewes.  Orf was diagnosed based on a positive PCR result.  Staphylococcus aureus was also isolated on culture, but was considered to be a secondary invader.