Vets warned of growing risk of deadly disease for sheep

The reappearance of a viral disease which can result in ewes aborting or even dying has triggered the Scottish Agricultural College into alerting vets throughout Scotland of the symptoms of an attack of maedi visna (MV).

So far this year, SAC have identified 11 cases of MV infection in flocks compared with only about three cases annually.

According to Brian Hosie, veterinary service manager with SAC Consulting, MV is not always something practice vets think of when presented with a problem flock.

"Despite feeding, sheep with MV infection lose condition, some will abort lambs and others may die. Many things can have affects like these on sheep so MV is not always on any vets' radar," he said.

He instanced the case of Isle of Wight farmer Andrew Hodgson, the owner of a 1,500 ewe commercial flock, who has estimated that MV reduced his flock's output by 20-40 per cent at a cost of 30,000-50,000 a year.

Hodgson's problems dated back to FMD in 2001 when he had to buy in local replacements. The batch did not last long, they performed poorly, quickly lost condition and some died. The symptoms did not return for seven years. "Looking back," Hodgson says, "I can now recognise some of the classic symptoms of Maedi Visna."

Hosie encouraged flockmasters to consider their biosecurity, especially since infection has also been found in a group of sheep during their first qualifying test to join a MV accredited flock.

The breakdowns so far this year have involved sheep from Texel, Charollais, Zwartble, Clun Forest, Border Leicester, Mule and Beltex cross breeds.

Lewis McClinton, chief executive of the Suffolk Sheep Society, described the increase in confirmed cases as a "wake-up call" for sheep farmers.

"I would strongly advise pedigree flocks to participate in the MV accreditation scheme and urge commercial ram buyers to source rams from accredited flocks."

A voluntary British MV accreditation scheme has existed for more than 20 years. Run by SAC, it provides a ready source of certified virus-free animals. It involves some 2,500 member flocks, offering accredited sheep from 64 different breeds.

However, with so few major outbreaks, some producers have taken the view that the threat posed by MV is not serious. Earlier this year there was a call to remove the division made at all local shows where MV and non MV sheep are shown.

Hosie warned that any reduction in vigilance or controls could have devastating results. "If this view was to prevail and the currently high membership of the scheme was to decline, there is every reason to suspect that MV would have the impact here that it already has on the continent".