Veterinary Services

Iodine and cobalt deficiencies were identified in a group of Scottish mule ewes on an Ayrshire farm. Poor growth, fertility, fleece condition and lactation were reported.  Similar deficiencies were confirmed by Ayr in a group of Scottish blackface gimmers.  Ill-thrift was evident in this batch that was purchased the previous October and failed to grow well at wintering.  Chronic fasciolosis was suspected as being a contributory factor to the ill-thrift problem on the basis of elevated liver enzyme values.  However, neither faeces samples nor postmortem material were available to clarify the situation.

Parasitic diseases

A total of 21 incidents of nematodirosis in lambs were recorded by SAC Centres this month.  This brought the total for 2008 to date to 121, compared to 69 incidents in the whole of 2007. 

The owner of 100 Texel-cross lambs near Edinburgh  reported acute diarrhoea and ten deaths within the group.  One dead and one live affected lamb were submitted for postmortem examination.  Both showed signs of recent scouring. Counts of 29,000 and 21,050 Nematodirus battus worms were recorded in small intestinal washes. The animal submitted alive had pale and enlarged kidneys.  Blood urea of 90 mmol/l (reference range 2.7–6.6 mmol/l) and creatinine of 1,040 umol/l (reference range <150 umol/l), suggested renal failure.  Subsequent histopathology confirmed nephrosis in this lamb and evidence of concurrent coccidiosis in both.

At Dumfries some 5,400 N. battus worms were identified in a ten-week-old lamb that developed diarrhoea and became moribund, before being euthanased.  This lamb was the second to die within a group that had received an anthelmintic dose some seven days earlier.  In order to check anthelmintic efficacy, faecal samples were collected and examined from other lambs in the batch. No nematode eggs were detected in these.  Probably the dead lamb was missed when dosing took place, rather than an anthelmintic resistance problem being present.  Interestingly multiple one mm diameter white spots with distinct centres were seen on the jejunal mucosa of the submitted lamb.  Histopathology showed that coccidiosis had led to a hyperplastic enteritis with mild crypt necrosis.  Identification of oocysts within the faeces identified these as Eimeria bakuensis, a species not generally regarded as pathogenic.

Three lambs were submitted from a farm where there were 12 sudden deaths in five days.  Intestinal torsion was diagnosed in one of the lambs.  The other two lambs were in poorer condition and showed signs of scouring and a typhlocolitis.  Significant burdens of Nematodirus worms and Eimeria crandallis were indentified in both lambs. A growth of Clostridium sordellii was isolated on anaerobic culture of the large intestine. The latter finding would normally be regarded as being of dubious significance. However histopathology revealed significant coccidial damage and areas of deep ulceration associated with bacteria resembling clostridia in the caecum of one lamb. It was postulated that intestinal damage caused by nematode and coccidial infection created conditions predisposing to C. sordellii multiplication. 

Resistance to levamisole was suspected in two flocks in the Thurso area. Use of this anthelmintic in the treatment of PGE led to no clinical improvement.  In a post-dosing faecal egg count seven days after treatment, worm egg counts in some animals still exceeded 4,000 per gram.

Chronic fasciolosis was diagnosed on an Ayrshire farm despite repeated flukicide treatment.  Investigations are ongoing into possible flukicide resistance.

Generalised and systemic conditions

Clostridial enterotoxaemia was diagnosed in a female dairy goat from a small herd in Ross-shire. The animal died suddenly one week post-kidding. Gross pathological findings were strongly suggestive of the diagnosis. Histopathology results were inconclusive but alpha and beta clostridial toxins were detected in thoracic and pericardial fluids. Advice was given concerning vaccination of the remainder of the herd.

Alimentary tract disorders

Two three-year-old ewes (one Texel cross, one Dorset) were submitted for postmortem examination from different farms. Both had similar histories of wasting while rearing lambs.  In one case there was a history of Johne’s disease among cattle on the farm, and two other ewes had lost condition over winter and died.  In the other case no ill thrift had been reported.  Both ewes were extremely thin at necropsy, but had no dentition problems.  The small intestine of the Texel demonstrated gross thickening of the mucosa with marked yellow colouration typical of the pigmented form of Johne’s disease.  The intestinal mucosa of the Dorset was thickened with a ridged or cobblestone appearance indicating a chronic enteropathy.  In both cases large numbers of acid-fast organisms typical of Mycobacterium avium subsp. paratuberculosis were seen on direct smears of the ileum. This confirmed the diagnosis of Johne's disease.

Nervous system disorders

A farmer in southern Scotland reported ewe deaths in a group of 150 on rented ground. Others were showing neurological signs. Two affected animals recovered after treatment with multivitamins.  A ewe was submitted alive (figure 5 - see top right-hand side).  It lay in left lateral recumbency  and when assisted to sit tended to throw its head to the left.  Menace and blink reflexes were present on both sides and there was no pyrexia, head tilt, opisthotonus, nystagmus or ear droop.  Muscle tremors were obvious around the muzzle.  Following euthanasia, no significant findings were detected on postmortem or bacteriological examinations. Neurohistopathology revealed a diffuse meningitis and severe localised purulent encephalitis with microabscesses in the brain stem.  These findings were consistent with a diagnosis of listeriosis although the clinical signs were not typical.

Skin diseases

Clinical cases of caseous lymphadenitis are often identified for the first time at shearing.  This was the case in a flock in the Thurso area where lesions were found in three Suffolk rams while they were being clipped. Bacteriology confirmed the diagnosis.