Veterinary Services

Nutritional and metabolic disorders

Cobalt deficiency affected a group of ill-thriven Scottish blackface lambs from an Inverness-shire flock. A similar picture was recorded by Dumfries, where blood samples were submitted from six flocks reporting ill thrift. Some of the serum vitamin B12 results fell below the minimum detectable level in the test.

Parasitic diseases

An eight-month-old Suffolk cross lamb was submitted for necropsy to investigate the cause of ill thrift and scour affecting at least 30 in a group of 40 lambs.  Three lambs had died.   Their dams were treated with moxidectin at lambing, and the same product was used on the ewes and lambs at clipping.  The lambs received a further worming treatment in mid-September (four weeks before submission) with ivermectin. The group were on good quality grass, but had not performed well all summer.  Faecal worm egg counts from five lambs within the group were 500, 2550, 1100, 1650 and 750 strongyle eggs per gram respectively.  Small numbers of Teladorsagia species were detected in the abomasum of the fatal case. It also had evidence of marginal cobalt status with a liver vitamin B12 of 0.13 ug/g wet material (WM) (reference range 0.11-0.19 ug/g WM).  SAC considered that the parasite burdens were probably due to reinfection following treatment but advice was given to investigate wormer efficacy and not to use Group 3 anthelmintics exclusively.

Parasitic gastroenteritis (PGE) was the commonest diagnosis made at Ayr during the month. Affected flocks were in Ayrshire, Renfrewshire, Argyll and Dunbartonshire, with concurrent chronic fasciolosis in two flocks.  A lowground flock in Ayrshire reported four lamb deaths in ten days despite anthelmintic treatment every four weeks. PGE was diagnosed on the basis of high trichostrongylid faecal worm egg counts.  Benzimidazole resistance was suspected and appropriate advice was given. No further deaths occurred and clinical improvement was reported after treatment with a Group 3 wormer.

A Dunbartonshire farm reported ill thrift in approximately half of its grazing lambs despite anthelmintic treatment.  PGE was again diagnosed on the basis of high trichostrongylid egg counts and the larvae of Protostrongylus sp. lungworm were also detected.

Three 18-month-old Suffolk gimmers, previously noted to be in poor condition despite a move to good grazing, were found dead.   At necropsy body condition was noted to be poor to the point of cachexia, with extensive faecal soiling.  The ribs in two of the animals were found to be brittle, consistent with osteoporosis, and the third showed marked under-development of the mandible.  Bacteriological and parasitological examination led to a diagnosis of PGE in all three animals.  The skeletal abnormalities were considered to be due to malabsorption resulting from  parasitism.

Nematodirus battus infection was seen in eight- to nine-month-old sheep from four farms in the Thurso area during the month. Severe, sudden onset scour and inappetence in some cases were seen.

Generalised and systemic conditions

Only four incidents of systemic pasteurellosis due to Bibersteinia trehalosi  were recorded by SAC this month compared with six outbreaks in October 2007 and 30 in the same month of 2006.  Conventional wisdom states that major peaks in diagnoses tend to be associated with spells of inclement autumn weather.  However, this appears to run counter to experience this year. October 2008 is likely to have been the wettest since 1954 and national mean temperatures were below average.

Respiratory tract conditions

Dumfries euthanased and necropsied a four-year-old Scottish blackface ewe that was thin at weaning and had continued to lose condition.  The ewe was tachypnoeic, dyspnoeic and pyrexic.  Following euthanasia frothy white fluid drained from the nostrils and necropsy revealed the entire left lung and anteroventral portions of the right was affected by ovine pulmonary adenocarcinoma (OPA).  This was the first diagnosis of OPA within this flock, although it had previously been diagnosed on another farm belonging to the same estate.

Nervous system disorders

Four incidents of louping-ill were recorded by SAC during October. In one incident the farmer reported losing up to 15 five-month-old lambs in one week whilst they grazed on silage aftermath.  Clinically the disease was said to progress rapidly from chewing mania, hyperaesthesia with running or circling, to lateral recumbency with paddling, nystagmus and rapid death.  The diagnosis was made through the detection of antibody to louping-ill virus in blood, with a predominance of IgM antibody, indicative of recent infection.  A diagnosis of louping ill was also made following examination of a blood sample from another group of Scottish blackface ewes. They were reported either to be dying suddenly, or after varying degrees of nervous dysfunction.

Recently SAC reported serological evidence of exposure to maedi-visna (MV) infection in a Dumfries-shire flock.  This month an adult mule ewe from the holding collapsed during a flock gather. It was in poor condition.  Although able to walk, it took short steps with the front legs and became inco-ordinated when encouraged to walk faster.  The limb reflexes were normal and there were no other neurological signs.  Necropsy revealed consolidation of the anterior third of both diaphragmatic lung lobes, with similar smaller areas of pneumonic change in other areas of the lungs.  Serology for MV was positive and lung histopathology identified changes suggestive of a lentivirus-type pneumonia.  Neuropathology identified a wedge-shaped lesion within the white matter of the spinal cord due to mononuclear perivascular cuffs.  This was surrounded by a granulomatous infiltrate and the associated white matter was severely demyelinated.  These findings suggested visna and immuno-histochemistry will be carried out to confirm this.