24 May 2002

Shearing risks spreading CLA

CARE at shearing will help limit spread of sheep disease, caseous lymphadenitis.

But development of a new blood test and persuading animal health companies to seek a licence to market a vaccine in the UK, offer the best opportunities for control.

That is the view of Graham Baird, vet investigation officer at SAC St Boswells. "Information from Australia suggests shearing has spread CLA between flocks on a few occasions, although it is unusual. But it is possible to spread it within a flock during shearing.

"Animals showing lumps and bumps, usually around the head and neck, should be sheared last," he says.

It is a growing problem. Studies conducted last year show 9-10% of terminal sire pedigree flocks may now contain infected animals. "Vets believe CLA may have spread further since then, as a result of restocking after foot-and-mouth."

For flocks infected with CLA, economic consequences can be dire. "One breeder recently told me he planned to sell 20 shearling rams this year, but five with CLA will have to be culled."

But there is hope for better control. A three-year joint project, between SAC and the Moredun Institute, to develop a more effective blood test than those available has just begun, says Mr Baird. "In time, flocks will be able to use this to cull infected sheep, eradicating the disease."

Having a vaccine licensed for use in the UK would also be a big step forward, he adds. &#42