Veterinary Services

Parasitic diseases

Over the course of a week, three mule gimmers died and five others were lagging behind from a group of 78 on a holding in the Dumfries area. On postmortem examination liver lesions consistent with acute fasciolosis were identified. Dissection of the liver tissues revealed immature flukes measuring between two and four millimetres, suggesting infection 4-6 weeks earlier.

Ayr Disease Surveillance Centre (DSC) received a report of a total of six Cheviot ewes that had died from a group of 150 over a ten day period. When one carcass was submitted for examination a diagnosis of acute fasciolosis and parasitic abomasitis was confirmed.

Six out of 120 Texel lambs on a holding in the Dumfries area died over the course of a week, with others showing evidence of scour. This group had been moved to fresh grass a few days earlier and the last recorded anthelmintic treatment, with ricobendazole, had taken place three and a half weeks earlier. When a carcass was submitted for examination, 26,000 worms were found within the abomasum and 146,000 in the small intestine, these being identified as mostly Trichostrongyles species. Further investigation of this outbreak was recommended, including the possibility that anthelmintic resistance may have contributed to the problem.

Generalised and systemic conditions

The beginnings of the normal autumn rise in diagnoses of systemic pasteurellosis due to Pasteurella trehalosi wasere noted in September. Aberdeen DSC confirmed the diagnosis in two four-month-old Scottish Blackface lambs. These lambs came from a group of 200, which had suffered seven sudden deaths since arriving on the holding a month previously. Systemic pasteurellosis was also confirmed in two gimmers, bought as part of a group of 420 some three weeks earlier. The farmer reported a total of five sudden deaths in the three days after the group were gathered for foot trimming.

Two Scottish Blackface ewes were submitted to the Edinburgh Centre for postmortem examination with a history of dramatic weight loss over the previous two or three weeks. In one case a diagnosis of Johne’s disease and concurrent parasitic enteritis was made. In the other ewe there was evidence of parasitic gastroenteritis (PGE), as well as foot rot and chronic fluke damage to the liver. However the most significant findings in this case were changes in the brain consistent with those of chronic listeriosis and sarcocystosis. It was felt that listeriosis may have lead to dysphagia and contributed to the ill-thrift.

Two goats from a farm park were submitted for necropsy when a diagnosis of clostridial enterotoxaemia was confirmed. Advice was given on vaccination and the possibility of reducing the concentrate ration being fed to the group.

Alimentary tract disorders

A six-month-old Scottish Blackface ewe lamb was submitted to the Edinburgh DSC for postmortem examination, this being the third death from a field of 60 over the course of a weekend. The lamb had clearly been scouring and internal examinantion revealed significant lesions within the gut. An area of necrosis and thickening was noted on the mucosa close to the ileocaecal valve and the wall of the caecum and large colon was thickened and oedematous, with areas of mucosal erosion and haemorrhage. Similar findings were noted in the small colon. Subsequent bacterial cultures yielded Yersinia pseudotuberculosis from the colonic lesions and an underlying PGE was also confirmed.

An adult Beltex ewe was submitted to Edinburgh for postmortem examination. This animal was part of a group grazing a field with cattle. Although concentrate feeding of the respective groups took place at either end of the field, there was felt to be a possibility of copper poisoning from the ewes consuming cattle cobs. The main findings on necropsy indicated an impaction of beet pulp had caused complete obstruction of the oesophagus, leading to bloat and thereafter to respiratory and circulatory failure. In addition, an estimation of liver copper revealed a level of 12,600umol/l (normal range 314-7850) suggesting that there was indeed a risk to the rest of the group. Separation from the cattle was therefore advised.

Nervous system disorders

Eight outbreaks of louping ill were recorded around Scotland during the month of September. At the Inverness DSC a Soay ewe was sacrificed for postmortem examination following the deaths of eight other ewes. This ewe was unable to stand, had opisthotonus and was paddling. A high antibody titre to louping ill virus was detected and louping ill virus was detected by real-time PCR. The neuropathology findings were of a diffuse lymphoid encephalitis and a mild meningitis. The Aberdeen DSC confirmed the same condition in ewes on two units. In one case ticks were observed on an affected animal and the farmer reported a total of 10 deaths. Louping ill had previously been confirmed in lambs on the same holding. In this case much of the antibody present in the serum of the affected animal was IgM, consistent with recent infection.

Three Scottish Blackface ewes died after exhibiting nervous signs in a flock in Inverness-shire. This hill flock had been dipped in April and a pour-on had been applied in July. A two-year-old ewe was found to have a number of ticks on its carcass and necropsy revealed multiple lung abscesses, some pleurisy and evidence of a verminous pneumonia. On neuropathology there was evidence of a semi-suppurative meningitis, non-suppurative encephalitis, neurone necrosis and neuronophagia. These findings were suggestive of louping ill and of a possible secondary bacterial infection. Specific immunohistochemistry for louping-ill was carried out and there was positive labelling in the neurons of the ammons horns and some in the pons, although this was limited in nature. The low level of labelling was felt to support the theory of a concurrent bacterial infection.

Two four-month-old Scottish Blackface-cross lambs were submitted to the Edinburgh DSC for postmortem examination. These animals had a history of ataxia and collapse of some two months duration. Three lambs were affected in a group of 60 and one other had died. Both lambs were well grown and in fair bodily condition, but histological examination of the brain and spinal cord identified changes consistent with a diagnosis of delayed swayback. An assessment of flock copper status was advised with a view to pre-tupping supplementation of ewes this year.