Veterinary Services

Toxic conditions

Copper poisoning was diagnosed in a Beltex hogg, one of two from a group of 30 on an Ayrshire holding that died on the same day. Postmortem examination revealed jaundice of the liver, dark kidneys and haemoglobinuria. Measurement of liver and kidney copper confirmed the diagnosis, but levels did not exceed the value at which the Food Standards Agency requires to be informed.

Parasitic diseases

Evidence of an early challenge by Nematodirus battus and Teladorsagia species worms was found in two, 10-week-old Charollais lambs. The group of 200 had failed to thrive and more than 12 had died. In addition both lambs had low liver selenium values. Also one lamb showed evidence of a purulent pneumonia from which Bibersteinia (formerly Pasteurella) trehalosi was isolated.

Acute fasciolosis was diagnosed in association with black disease as the cause of three sudden deaths of heavily pregnant ewes on a unit in the Thurso area. While there was known to be chronic liver fluke problem on the farm in question, no cases of acute disease were recorded previously.

Haemonchus contortus infection was diagnosed following the necropsy of a ewe from a flock in Caithness. The homebred animal had originally been suspected of suffering from Johne’s disease because of its anaemia and poor bodily condition,

Generalised and systemic conditions

Septicaemia and pneumonia due to Mannheimia haemolytica was diagnosed as the cause of death in lambs three to four weeks of age in a well managed flock in Easter Ross. Slightly older lambs were found dead on two other farms in the Thurso area, with mortality rates identified as three percent and 15 percent respectively. Necropsy revealed acute septicaemia and pneumonia due to B. trehalosi in one case and M. haemolytica in the other. In neither case were the ewes vaccinated against Pasteurella infections.

Alimentary tract disorders

A well grown two-month-old single Texel cross lamb was found dead and bloated only hours after being clinically normal. At postmortem examination the caecum was distended with gas and the intestines were very congested. A 360-degree torsion was present and a diagnosis of intestinal haemorrhage syndrome (red gut) made. It was noted that the lamb born to the same ewe in 2006 had died under similar circumstances.

A three-year-old mule ewe suffering from anorexia and weight loss, was submitted in a comatose state to the Dumfries DSC. A large quantity of clear ascitic fluid was demonstrated and the liver was misshapen, with diffuse, nodular, white lesions throughout (figure 1 - top right-hand side). Similar changes were seen in the spleen and lesions were also noted in the mesentery, the small intestine and the abdominal lymph nodes. Histopathology provided a diagnosis of cholangiocarcinoma with metastasis.

Respiratory tract conditions

Ovine pulmonary adenocarcinoma (OPA) was confirmed in an eight-month-old ram lamb from an Aberdeenshire unit, which had been housed since birth. This particular holding had a history of OPA, although the condition is uncommon in animals of this age.

Reproductive tract conditions

Disease caused by infection with border disease (BD) virus was confirmed in four flocks in the Aberdeen and Dumfries areas. Each affected flock reported the birth of non-viable lambs with signs of tremor. In one case a significant abortion problem was also reported. On each occasion live affected lambs were submitted for examination and BD virus antigen was detected by PCR. In two cases the flock owners reported the incursion of stray sheep after tupping. On one of these units a selection of four resident and four stray ewes were serologically screened. Seven samples showed BD antibody titres and one sample from a stray sheep contained BD antigen confirming it was persistently infected with virus. In both cases the SAC recommended that sheep suspected or confirmed as introducing the disease were removed, and that the year’s lamb crop was not retained as replacements.

The owner of a farm in Ayrshire reported marked goitre affecting four stillborn lambs. The flock concerned was described as a hobby farm, on quarry land that was very sandy. Advice was given on iodine supplementation in order to avoid the problem in future years.

The predominant diagnoses in cases of abortion in Scotland were infection by Toxoplasma gondii and Chlamydophila abortus. Other outbreaks were associated with infection by Streptococcus uberis, Streptococcus dysgalactiae, Salmonella Montevideo, Bacillus licheniformis and Arcanobacterium pyogenes. A review of national trends will appear in the SAC VS May report.

Musculo-Skeletal conditions

Ten outbreaks of arthritis due to Streptococcus dysgalactiae subsp. dysgalactiae infection were recorded in Scotland this month. In one case a farmer with a flock in Perthshire reported the loss of 20 or more lambs from a group of 1,500 suffering from acute lameness and swollen joints. When a live affected lamb was submitted for necropsy the shepherd estimated that a further 50 lambs had been treated with antibiotics on that morning alone. The submitted lamb was found to be recumbent with visible swellings of the elbows, stifles and hock joints. This was found to be due to an excessive quantity of cloudy synovial fluid within the joint spaces, with green purulent discharge apparent over the articular surfaces. Streptococcus dysgalactiae was isolated in pure culture from the stifle and knee. On other farms the same infection was manifest as abscesses in the atlanto-occipital joint of lambs and the bacterium was isolated from cases of fibrinous pericarditis and pleurisy.

Nervous system disorders

Twelve hill hoggs died from a group of 40 on a farm in Perthshire, with some reported to have shown signs of tremor and recumbency prior to death. The owner also reported the presence of large numbers of ticks on the group as a whole. When one live affected and one dead animal were submitted for examination, no significant gross lesions were recorded on necropsy. However, in each case subsequent histopathology confirmed a severe non-suppurative meningo-encephalitis, consistent with a diagnosis of louping ill (LI). When LI serology was performed on serum from the live hogg a high titre composed largely of IgM confirmed the diagnosis.

An 11-month-old Texel cross hogg was submitted alive to Dumfries. The animal could stand, but appeared dazed and was blind in the right eye. A further four similar cases had been seen while the group was away at wintering and on their return home. The clinical signs described included salivation, recumbency and death. Necropsy revealed severe purulent meningitis, although bacterial cultures from affected areas were sterile (figure 2 - see top right-hand side). However, histopathology identified well-organised abscesses in the fore and mid brain. These abscesses had a central zone of liquefactive necrosis, surrounded by zones of coagulative necrosis, neutrophils and macrophages, with some fibrosis and mineralization also seen. Infection with a slow-growing bacterium was suspected and caseous lymphadenitis due to Corynebacterium pseudotuberculosis is a possibility. This possibility will be investigated through the use of immunohistochemistry.

Skin diseases

Thurso diagnosed sheep scab in three flocks. In two flocks samples were submitted after avermectin pour-on treatments failed to cure pruritis in sheep. Avermectin pour-on products do not have a licenced claim for the treatment of sheep scab. In the third flock the diagnosis was associated with re-infection of treated sheep from a neighbouring flock. Aberdeen also diagnosed sheep scab. This outbreak was in a flock of Scottish Blackface ewes and the farmer reported finding strays in the flock several weeks previously