Caseous Lynphadenitis in Sheep
Summary written by Michael Fontaine BSc PhD
Taken from Moredun Foundation Newsheet Volume 5 No. 1 (2009)
- Caseous lymphadenitis (CLA) is a chronic bacterial disease of sheep and goats characterised by abscess development in the lymph nodes and other tissues.
- CLA can result in chronic wasting, resulting in significant welfare and financial implications.
- CLA lesions can necessitate carcase trimming at abattoir, and in severe cases may lead to carcase condemnation.
- Currently (February 2009), the disease is well-established within Great Britain and Northern Ireland.
- C. pseudotuberculosis, the causative organism of CLA, can survive in the environment for several months and is highly infectious.
- Antibiotic treatment is ineffective.
- Although CLA was once mainly seen in the terminal sire breeds, the disease has now become established within the national flock.
- Direct contact with pus from CLA lesions is the main source of new infections, however, infectious aerosol from animals with lung lesions has also been shown to be a means of disease spread.
- Sheep or goats displaying chronic abscesses should be isolated and subjected to immediate veterinary and bacteriological investigation
- Control measures should include quarantining (of both animals and premises), screening of imported animals, the cull of infected animals and rigorous hygiene procedures. Shearing equipment should be dipped in strong disinfectant or chlorine bleach before and after use.
- Older animals should be handled last during routine procedures.
- A heightened awareness of this disease and prompt veterinary investigation of suspect cases is essential. At present, CLA is not a notifiable disease.
- A CLA diagnostic blood-test has been developed by Moredun and SAC scientists and a testing service is provided by SAC.
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