Veterinary Services

Nutritional and metabolic disorders

Hypocalcaemia and pregnancy toxaemia were confirmed at postmortem examination of three Lleyn ewes from an Aberdeenshire holding, one of which was submitted alive, in lateral recumbency and paddling. In another local flock, 30 of 500 ewes died over the course of two weeks. These ewes were being fed whole crop oats by way of a recently introduced "snacker" feeder. Ruminal acidosis was confirmed in two ewes found dead and submitted for necropsy. Large quantities of whole grains were present in the rumen, with very limited fibre.

Edinburgh found high serum beta hydroxybutyrate (BOHB) values in blood samples from seven of 10 triplet-bearing ewes on a farm that experienced losses from twin lamb disease last year. This year the feed to this group was increased for a week. Despite this extra feed, BOHB levels varied from 1.5 to 5.2 mmol/l, while the mean for the group of 10 was 2.04 mmol/l (reference range ≤ 1.2 mmol/l).

Toxic conditions

Ayr diagnosed rhododendron poisoning in a ewe that was euthanased in extremis. It was one of a group of lowground sheep that broke into neighbouring gardens. Six ewes were found comatose. One died and another was euthanased. Postmortem examination revealed hepatic degeneration and the leaves and buds of a dwarf Rhododendron species within the rumen. Dumfries obtained a similar diagnosis when 12 Shetland sheep became ill some 24 hours after being chased out of a garden. They were found in lateral recumbency, showing signs of paddling, opisthotonus, teeth grinding and salivation. Necropsy revealed leaves of a species of Pieris in the rumens. This shrub, which like Rhododendron is part of the Ericaceae genus, is highly toxic, although, since it is not native to the UK, incidents of poisoning are limited to garden break-ins such as this case.

Parasitic diseases

SAC Centres recorded 75 incidents of chronic fasciolosis during the first two months of 2008, compared to 30 in the same period last year. Seven incidents of acute fasciolosis were diagnosed and this is comparable with nine in the same period during 2007. Ayr noted that chronic fasciolosis was the commonest diagnosis during the month. Flocks in Ayrshire, Argyll and Renfrewshire were affected. On one Ayrshire farm, five pregnant ewes died during the three weeks after housing. Lesions typical of chronic fasciolosis were evident in the ventral lobe of the liver and parasitic bronchitis due to Dictyocaulus filaria and parasitic enteritis due to Trichostrongylus spp were also evident. As the group was treated for fasciolosis in October and January, the SAC VS advised investigation of the possibility of flukicide resistance, including post-dosing anthelmintic efficacy checks

A four-year-old ewe from a farm in Easter Ross showed severe liver damage due to chronic liver fluke infection. Three ewes died in the group of 400 that was last treated for worms and fluke in October 2007. Chronic liver fluke infection was also diagnosed on the basis of faecal egg counts in five submissions from the Uists and Barra and in four submissions from Skye. No dosing history was supplied with three of these submissions, while the remaining six were pre-dosing checks. Small numbers of liver fluke eggs were also noted in a sample taken two weeks after dosing with Triclabendazole. A repeat sample was advised in this case, as it was possible that the liver fluke burden had been cleared but eggs were still being shed in the faeces.

Alimentary tract disorders

A Suffolk lamb from a group of 45 grazing on a lowground Ayrshire farm was submitted for necropsy with a history of dullness and diarrhoea. Enteritis was evident on examination and histopathology revealed widespread damage to mucosal glands associated with numerous coccidial forms, particularly, but not exclusively in the large intestine. In addition, epsilon clostridial toxin was demonstrated in bowel filtrate. Clostridium perfringens Type D enterotoxaemia may have been associated with the coccidial damage. SAC recommended a review of clostridial vaccination procedures and coccidiosis treatment.

Respiratory tract conditions

Edinburgh confirmed ovine pulmonary adenocarcinoma (OPA) a 10-month-old Suffolk-cross male lamb and in a four-year-old Mule ewe from different farms. The lamb showed signs of respiratory disease for some weeks. OPA is uncommon in this age of sheep. The ewe showed signs of respiratory disease for only 12 hours before death and examination revealed a severe, acute suppurative pneumonia from which Mannheimia haemolytica was isolated.

Reproductive tract conditions

Abortion due to Mannheimia haemolytica infection is uncommon but was diagnosed on examination of a single Texel lamb and a small sample of placenta. This was one of twins born to a gimmer that died shortly after lambing. Bacterial culture of the placenta yielded a heavy, mixed growth including M. haemolytica, while a light but pure growth of M. haemolytica was obtained from the stomach content.

Nervous system disorders

Listeriosis was diagnoses on the basis of histopathological examination of the brains of two Scottish blackface hoggs from a farm in Inverness-shire. Twenty animals from a group of 500 hoggs fed indoors were reported to have died after exhibiting central nervous signs.

Skin diseases

Aberdeen and Thurso both reported outbreaks of pediculosis due to Bovicola ovis lice infestation. The Aberdeen outbreak was detected in wool from a Suffolk cross ewe from a group of 82 bought-in ewes that developed pruritis, alopecia and crusting of the skin over the preceding two week period. Thurso reported three cases of Bovicola ovis infection, two in flocks that had been treated for scab with injectible macrocyclic lactone (ML). There was also one case of sheep scab in a flock that was treated with an injectible ML in November 2007.

Two rams were submitted to Dumfries with a history of slow growing masses between the horn and the ear. This problem was seen in the flock 14 years ago and mainly affected older Scottish blackface rams. Most cases were recognised in the autumn, when affected animals gradually lost condition and had to be culled. At least one animal was affected each year. None recovered and the growths did not resolve with antibiotic treatment or cautery. In both animals, the growths were attached at the lateral horn base and purulent material collected between the growths and the horn. The underlying horn was necrotic and pus was also present in the horn sinus, the frontal sinuses and the nasal cavity. In cross-section the growths were firm, white and smooth. Histopathology showed that they were made up of organised granulation tissue. One section contained spicules of bone, suggesting invasion of the cortical bone by the granulation tissue. Orf virus was detected by PCR and the SAC advised vaccinating the rams against orf to try and prevent further cases.