2013-06-07 facebooktwitterrss
Breeders Urged to Test Sheep for CLA Disease before Sales

With sheep shearing underway and the first of the season’s ram sales soon, experts from SRUC recommend that, in preparation for the sale, UK breeders test their sheep for CLA or caseous lymphadenitis.

CLA is a highly infectious disease, often spread during shearing and signs of it can exclude breeding sheep from many premier markets

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It is believed CLA first reached the UK in 1987, through goats, imported from Germany. The first Scottish case was identified in the Borders in 1996. It is now believed to be present in many of the terminal sire breeds, but others, like Cheviots are also affected, as are commercial flocks.

“Evidence of such a nasty disease can not only lose a breeder sales”, says Lynn Batty, Veterinary Investigation Officer with the SAC Consulting arm of the College. ”Even worse is the loss of reputation caused when a buyer takes the sheep home and finds his new purchases are harbouring infection and putting the rest of his flock at risk”.

CLA is a chronic disease, caused by a bacterium, Corynebacterium pseudotuberculosis, which can also infect humans. Some sheep and goats develop multiple abscesses in their lungs and liver and fail to thrive. The most noticeable sign is the presence of lumps or bumps on the skin, but not every infected animal will have them.
There is no effective treatment for CLA. Despite the best efforts of the National Sheep Association and other bodies there is no evidence that a licensed vaccine against CLA infection will be available in the UK for some time yet. Meanwhile blood testing is the best way of identifying infection.

Following discussion with industry leaders, the Premium Sheep and Goat Health Schemes, managed UK wide by SAC Consulting, are advising flock owners to blood test the animals they plan to present to this summer’s breeding sales now. These sheep should then be kept isolated from the rest of the flock until they are sold.

According to Aberdeen-based Lynn Batty, who works with the health schemes, by presenting sheep from a batch of blood-test negative animals, breeders can be certain they are doing all they can not to spread CLA.

"However we are also recommending that as a further check, anyone buying breeding stock should re-test the animals for CLA when they get home. This approach will help to prevent the spread of this highly infectious disease.”

The bacteria infect sheep through cuts or nicks. They are often spread during shearing after abscesses are punctured and pus contaminates the shearing head or blades. People working with infected sheep are at particular risk and it is recommended that they take precautions such as the wearing of protective clothing.

The disease is of real economic significance. In the EU, carcases with two or more CLA abscesses are condemned. Where there are only one or two abscesses, these may be trimmed. There is no antibiotic effective in tackling CLA. Vaccines are available but they are comparatively expensive because none are presently licensed in the UK.

SRUC


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