Veterinary Services

Copper deficiency was confirmed in a group of 37 five-month-old Suffolk lambs from Aberdeenshire.  Animals in the group were scouring and underweight. Performance declined  noticeably since weaning took place in June. In the same area cobalt deficiency was diagnosed in a group of five-month-old Texel and Suffolk lambs with a history of failure to thrive, dry coats and some scour. The same diagnosis was made in a batch of ill-thriven fattening lambs on an Argyllshire farm on the basis of mean and individual vitamin B12 values below the reference range. Hyposelenosis and cobalt deficiency were  diagnosed in two groups of ill-thriven lambs on an Ayrshire farm. Elevated pepsinogen values in one group indicated previous helminth challenge likely to have contributed to the problem.

Parasitic diseases

Parasitic gastroenteritis was diagnosed in carcases submitted to St Boswells from ten different holdings during the month.  The age range of affected lambs was three to six months and the highest mortality rate reported was eight percent.  Teladorsagia circumcincta was the most prevalent species identified. It was present in nine outbreaks, with total worm counts as high as 63,000.  In one case Haemonchus contortus was also identified.  In the only outbreak not to involve Teladorsagia, 29,000 Nematodirus species worms were found in the single carcase examined.  In this case faeces from the batch of four-month-old lambs were free of worm eggs prior to being moved onto hay aftermath.  Ten days later clinical disease became apparent.  SAC concluded that Nematodirus larvae were present in the aftermath field, rather than the lambs being infected when turned onto the area. SAC also suggested that the severe clinical signs indicated poor immunity since the group had not encountered a significant prior Nematodirus challenge. 

The owner of a flock in Moray reported ill thrift and 12 deaths in a group of 250 Scottish blackface and crossbred lambs. Five lamb carcases submitted for necropsy showed evidence of parasitic gastroenteritis and poor vitamin B12 status. Treatment of the remaining animals with moxidectin reduced faecal egg counts to less than 50 epg at 16 days post-dosing. SAC suggested that high parasite challenge resulted from the ewes not being wormed around lambing. Returning growing lambs to pasture previously grazed by those same ewes and lambs earlier in the season had made the situation worse.   
 
Alimentary tract disorders

Johne’s disease was diagnosed in two Scottish blackface ewes euthanased in extremis.  Both had a history of chronic weight loss with occasional diarrhoea.  Severe thickening and corrugation of the distal small intestine with yellow pigmentation was evident in each case. The diagnosis was confirmed by demonstration of acid/alcohol fast bacilli typical of Mycobacterium avium subspecies paratuberculosis in the affected intestine.  The same diagnosis was made in Dumfries when two emaciated mule ewes weighing 30 and 31kg were submitted alive for post-mortem examination. Again the distal jejunum, ileum and caecum were thickened and pigmented. Examination of Zeil Nielsen stained smears confirmed the diagnosis.  The owner of this flock of 550 reported that he saw two or three similar cases every year. 

Respiratory tract conditions

A mule ewe found dead on a Dumfries-shire holding was submitted for necropsy. The entire left lung was found to be firm and grey, with similar changes in the right lung confined to the apical and cardiac lobes.  A diagnosis of ovine pulmonary adenocarcinoma was confirmed on histopathology. The ewe was also seropositive to maedi-visna (MV) virus. No evidence of MV associated lung changes were seen at histopathology.  Further screening of the flock will now be carried out to determine the extent of MV infection.

Nervous system disorders

Focal symmetrical encephalomalacia, caused by the epsilon toxin of Clostridium perfringens type D, was diagnosed in a four-month-old Charollais cross ram lamb. It was submitted to Aberdeen in lateral recumbency with intermittent paddling and nystagmus. Although the ewes in the flock were on a clostridial disease vaccination programme, vaccination of older lambs was not carried out.

Two three-month-old lambs from different holdings in the Thurso area were presented for necropsy. The history in each case was of head tilt, opisthotonus and death, despite treatment.  The lambs were from groups recently moved to fresh grazings.  Histopathology of the brains in each case confirmed lesions of severe acute cerebrocortical necrosis.