Veterinary Services

The owner of a group of mule and Scottish blackface lambs reported that six of them had become weak and collapsed during a gather.  One 9.5kg lamb submitted alive for postmortem examination showed facial swelling and ear lesions consistent with photosensitisation.  There was evidence of scour and hypoproteinaemia, and a mixed burden of 10,800 Teladorsagia and Trichostrongylus worms were recovered from the abomasum.  Measurement of liver trace elements revealed cobalt of < 0.05 ug/kg DM (reference range > 0.06 ug/kg) and selenium of 0.16 mg/kg DM (0.9 – 3.5 mg/kg). 

Toxic conditions

 
Copper poisoning was diagnosed in an 18-month-old Wensleydale wether. The group received supplementary feed whilst at grass and this animal was in a fat body condition.  Liver copper was 16,100 umol/kg DM (reference range 314 - 7,850 umol/kg DM) and kidney copper 3,390 umol/kg DM (reference range ≤787 umol/kg DM).  The owner was advised to review the dietary management.

Inverness received a three-year-old Zwartble ewe for necropsy following its sudden death. The gross findings suggested septicaemia.  However on liver histopathology the use of rhodinine stain revealed heavy deposits of copper and the liver copper level was found to be 24,100 umol/kg.  Although such a copper level is grossly above normal levels, in this case there was no visible evidence to indicate that this had yet initiated a haemolytic crisis.

Parasitic diseases

Parasitic gastroenteritis was diagnosed as contributing to ill thrift with some deaths in a batch of four-month-old lambs in Argyll.  The pooled faecal nematode egg count and elevated pepsinogen levels both indicated a significant worm burden.  Hypoalbuminaemia evident in the lambs sampled was consistent with endoparasitism and elevated liver enzymes values suggested that chronic fasciolosis may also have been involved.  Glutathione peroxidase levels were below reference ranges indicating hyposelinosis.  Parasitic gastroenteritis with coccidiosis and cobalt deficiency was diagnosed in a second flock of four-month-old lambs in Ayrshire.  SAC CVS considered that the trace element deficiency exacerbated the effects of parasite challenge in both cases, by impairing the animals’ immune response.

Generalised and systemic conditions

Ayr diagnosed clostridial disease in three ewes that died suddenly in different flocks.  In one ewe Clostridium novyi was detected in damaged ventral cervical musculature, and in a second ewe C. novyi and Staphylococcus aureus were isolated from a case of acute mastitis.   Alpha toxin of Clostridium perfringens was isolated from gut filtrate of a third ewe that was also hypocalcaemic.  These three animals were all reported to have received a multivalent clostridial vaccine earlier in 2010.  The SAC CVS recommended a review of vaccine policies to ensure the correct storage and administration of the vaccine.

A two-year-old Toggenburg goat was submitted for necropsy following sudden onset haemorrhagic diarrhoea and death. Gross findings included marked enteritis and colitis, and enlargement of the mesenteric lymphoid tissue. Clostridium perfringens was isolated and epsilon toxin recovered from the intestinal content.  Interestingly a pure growth of Clostridium sordellii was isolated from the mesenteric lymph node, although the clinical significance of this is unclear.  Concurrent parasitic enteritis was also a factor in this case.

Two ewe lambs were found dead within a week from a group of 600 on a Borders farm.  The carcase submitted for necropsy showed extensive haemorrhage in the subcutaneous tissues of the thorax and abdomen, although no puncture wounds were visible.  The affected tissues were invaded by the bacteria Arcanobacterium pyogenes and there was histological evidence of a more generalised bacteraemia.  The previous year this farm had suffered from dog worrying, and it was suspected that this may have been the cause of the lesions in this case too.

Nervous system disorders

A live lamb presented at St Boswells was dull, recumbent and paralysed, and showing signs of strabismus and blindness.  Listeria monocytogenes was subsequently cultured from the brainstem.  Although this was the first death reported in the batch of lambs on this farm, two percent mortality was recorded amongst the ewes over a period of two months.  The affected ewes had reportedly shown similar clinical signs, with some recovering but being left blind.  None of the sheep had access to silage feeding.