Veterinary Services

For much of Scotland, the first significant outbreaks of nematodirosis are recognised in May, with diagnoses of the condition tending to reach a peak in June each year.  In 2010 a total of 35 outbreaks were recorded by SAC DSCs in May, and 58 in June.  This was compared to 19 and 41 in the respective months during 2009.  The overall total of diagnoses for 2010 was also higher at 134, which was 40 outbreaks more than the previous year.

Such annual variations can be closely correlated to recorded temperatures, which have a direct effect on the hatching of the infective L3 larvae of Nematodirus battus.  If a mass hatch coincides with the start of significant grazing by spring-born lambs, then outbreaks of the condition are likely. When investigating a possible nematodirosis outbreak, it is important to bear in mind that immature N. battus worms cause clinical signs.  Consequently a lamb may suffer from a severe or even fatal case of the disease, while no worm eggs are detectable within the faeces.  As a result, the examination of lamb carcases is frequently required to establish the diagnosis.

Nutritional and metabolic disorders

Pregnancy toxaemia and/or hypocalcaemia were diagnosed in 16 flocks from throughout Scotland. This compares with 12 flocks in March 2010. In one Lanarkshire flock pregnancy toxaemia in association with chronic fasciolosis left four ewes dead two weeks before lambing was due to start.   Dumfries used the results of serum beta-hydroxybutyrate (BOHB) estimation to confirm marked energy deficiency in a group of ewes displaying significant weight loss. 

Parasitic diseases

Chronic fasciolosis was diagnosed in a group of ewes on an Argyllshire farm showing “bottlejaw” (submandibular oedema) despite preventative treatment. Further investigation of a possible flukicide resistance was instigated.

Generalised and systemic conditions

Ayr investigated copper poisoning in two zwartble ewes that displayed neurological signs and jaundice prior to death. Both carcases were in excellent bodily condition and jaundiced. The livers were enlarged, friable and a pale bronze colour, and the kidneys had a slight orange-brown discoloration. Tissue biochemistry confirmed elevated copper levels and serum copper values were elevated in the cohort. Histopathology changes were consistent with severe hepatic lipidosis rather than a haemolytic crisis suggesting chronic poisoning. SAC C VS suspected that high levels of concentrate feeding over a prolonged period had led to an accumulation of copper in this susceptible breed. 

Inverness diagnosed multicentric lymphoma in a five-year old charollais ewe submitted for postmortem examination with a clinical history of respiratory signs and exercise intolerance. Necropsy identified multiple firm masses infiltrating the lung parenchyma (Figure 3 - see top right-hand side), creating adhesions between intestinal loops and surrounding both kidneys.  Histopathology confirmed the diagnosis

Alimentary tract disorders

Dumfries diagnosed Johne’s disease in two cheviot ewes submitted due to emaciation despite preferential feeding. In each case corrugated, pigmented lesions were found extensively throughout the small intestine, caecum and colon.  Johne’s disease was also diagnosed in a four-year-old hebridean ewe, however in this case lesions were non-pigmented lesions and confined mainly to the ileum. 

Reproductive tract conditions

Ayr identified Clostridium sordellii as the cause of metritis and toxaemia due in a Lanarkshire hill flock experiencing abortions and ewe losses. The affected group of draft ewes had not yet received a pre-lambing booster dose of clostridial vaccine.

Musculo-Skeletal conditions

Dumfries diagnosed nutritional myopathy in a six-week-old lamb that died shortly after being found recumbent. This was the fifth such death in the flock. Pale skeletal muscle was noted at necropsy and histopathology confirmed the diagnosis.  Tissue analysis found normal liver selenium levels and vitamin E levels only slightly below the normal range. SACCVS considered that an earlier deficiency may have been subsequently corrected.

Nervous system disorders

Ovine infectious keratoconjunctivitis was confirmed in a hill flock of Scottish blackface and cross-bred ewes that had experienced problems since July 2010, when sheep from a neighbouring farm had strayed onto the holding.  A clinical response to parenteral long acting oxytetracycline was seen but recurrence was common. Swabs collected from six affected sheep (Figure 4  - see top right-hand side) were positive for Mycoplasma conjunctivae by PCR and a mixed growth of Streptococcus species, coliforms and Moraxella species were isolated on bacterial culture. 

St Boswells diagnosed sarcocystosis and pneumonic pasteurellosis in two emaciated hoggs submitted with a history of recumbency and paddling.  These hoggs had lost weight in the snows of December and January despite supplementary feeding being made available.  Mannheimia haemolytica was isolated from pneumonic lung tissue and non-suppurative encephalitis associated with the presence of protozoal organisms was identified by neuropathology.

Skin diseases

 
Perth confirmed periorbital eczema due to Staphylococcus aureus as the cause of facial lesions seen in two Scottish blackface ewes from a Stirlingshire flock.  Pasteurella multocida, Streptococcus dysgalactiae and Streptococcus uberis were also recovered from the material submitted however SAC C VS considered these to be opportunist pathogens.