Veterinary Services

Alimentary tract disorders

A four-year-old Lleyn ewe was submitted to the Dumfries DSC for euthanasia and necropsy after losing body condition and scouring during the previous three weeks. Examination of blood samples from the animal revealed evidence of severe hypoalbuminaemia, with serum albumin measured at 11g/l (normal range 28 –34 g/l), while globulin levels remained normal at 37g/l (normal range 38 – 42g/l). On postmortem examination there was widespread tissue oedema, enlargement of the mesenteric lymph nodes and a gross thickening of the ileum, colon and caecum. A Ziehl-Neelsen stained smear of the ileal mucosa was positive for the presence of acid-fast bacteria, consistent with a diagnosis of Johne’s disease.

A sample of faeces from a six-month-old ram lamb with a history of persistent scour was submitted to the Thurso DSC. This was the only animal affected on the holding and it had failed to respond to prior treatment for coccidiosis. Examination of this sample confirmed the absence of coccidial oocysts, and also failed to identify either worm or liver fluke eggs. However, subsequent bacterial cultures confirmed the presence of Salmonella derby.

A four-month-old Texel ewe lamb with a history of a sudden onset, bloody scour and abdominal pain was submitted to the Edinburgh Centre, after being euthanased on humane grounds. Others within the same group were reported to show similar but less severe signs. It was indicated that treatment for coccidiosis had previously been given to the group. At necropsy of the lamb the caecum and proximal colon were thickened and contracted. In addition there were haemorrhages over the mucosa and adhesion of the flocculent gut contents in some areas. The wall of the distal colon was diffusely thickened, oedematous and reddened. The contents here were bloody and fluid. Histology of the caecum and colon showed evidence of extensive coccidiosis with erosion and inflammation. Examination of the distal colon revealed that the mucosa here had been completely lost and replaced by a layer of necrosis and inflammation. Examination of Gram-stained sections of caecum and colon indicated a mixed bacterial population, including Campylobacter-like organisms present in significant numbers. This was followed by the isolation of Campylobacter coli in a profuse growth from the caecum, colon and rectal contents. Subsequent screening of other less severely affected lambs, failed to identify coccidial oocysts or Campylobacter coli on culture. It was concluded that the group having shown scouring as a result of coccidiosis had partially resolved with treatment, but that this individual had subsequently developed a severe, erosive typhlocolitis due to a secondary Campylobacter coli infection.

The owner of a flock in the Edinburgh area reported the deaths of seven ewes and one lamb, which occurred in a single field over a five-day period. All the affected animals were said to have scoured for some 24-48 hours prior to death. The first submission was of a live but collapsed ewe and another dead ewe. Necropsies revealed ascites and enlarged pale kidneys. Both animals had significant quantities of whole barley grains in their rumens and one of the two showed a severe rumenitis, with extensive adhesions to the omentum (figure 2; use PDF link on right). Two days later a third ewe was submitted for necropsy and similar kidney changes were noted, along with oesophageal ulceration, pulmonary oedema and hyperaemia of the intestines. Examination of the kidneys from each of the three sheep revealed extensive tubular damage, with nephrosis and crystal formation. Discussion with the farmer indicated that barley was not at the time being fed to the ewes, with the most likely scenario being that they had discovered the grain whilst being gathered for shearing. It was concluded that this consumption had led to rumen acidosis, which in-turn developed to a rumenitis in one case. It was proposed that the renal damage had occurred secondary to the acidosis and dehydration, but the possibility that a nephrotoxin may have been ingested in addition to the barley, could not be excluded.

Respiratory tract conditions

A farmer with 40 Beltex rams reported the loss of a number of animals during the summer months during successive years, although these sudden deaths were rarely investigated. When one such animal was lost from the group after a short period of dyspnoea, the carcase was submitted for necropsy. Bodily condition was found to be good, although autolysis was advanced in the hot weather. There was oedema and congestion of the head and neck, and the local drainage lymph nodes were enlarged. There was marked distortion of the larynx, with necrosis and abscessation in the left side. This had led to a total occlusion of the lumen. In addition there was a large amount of bloody fluid within the trachea and pulmonary congestion was marked. A diagnosis of laryngeal chondritis was made this being a recognised problem of the Beltex breed. It was considered that the exceptionally hot, muggy weather may have been a contributory factor in this case, leading to panting amongst the rams and predisposing this animal to the development of laryngeal lesions.

Nervous system disorders

The owner of a group of 100 gimmers on an Inverness-shire holding reported that within ten days of the flock being moved to another field, three had died and another two were found to be in lateral recumbency, paddling and pyrexic. There was no response to treatment with antibiotics or vitamins. The two affected animals were subsequently euthanased and submitted for postmortem examination. No ticks were found on the carcases, none had been seen on the sheep found dead and the field that the sheep had been moved on to was not known to carry the parasite. However, the lesions recorded by neurohistology following necropsy of the two gimmers were consistent with a diagnosis of louping ill and both animals showed high levels of circulating antibody to louping-ill virus

Brain histopathology also confirmed lesions consistent with louping ill in a two-year-old Scottish Blackface gimmer, which was presented at the Aberdeen DSC in a collapsed state and with a heavy burden of ticks. Several other deaths were reported in the group of 300.

Skin diseases

A four-month-old Berrichon du cher lamb was euthanased and sent for postmortem examination after it developed extensive skin lesions over the mouth, ears and eyelids, around the groin and over the hind legs and feet (see Figure 3; use PDF link on right). A marked lymphadenitis in the head and neck region was also demonstrated. The 50-ewe flock from which this animal came had lambed indoors, with the young lambs being vaccinated against orf at between two and three days of age. Some time later the owner had noticed that a proportion of the lamb group had developed lesions resembling bunches of grapes at the vaccination site and around their mouths. These lesions improved in all affected lambs except the individual submitted for postmortem examination. Orf virus was isolated from the lesions in this animal and DNA typing confirmed it as a "wild" type of the virus rather than the vaccinal stain. It is not known why this lamb was so severely affected.

Caseous lymphadenitis was confirmed in rams from two flocks in Shetland. In each case the affected animals had been purchased and imported from mainland Scotland, one in 2004 and the other in 2005. The affected lymph nodes were first identified at shearing.