This page provides useful information relating to Caseous Lymphadenitis (CLA) including signs, how the disease is spread and advice on preventing the spread of the disease.

What is Caseous Lymphadenitis (CLA)?

Caseous Lymphadenitis (CLA) is a bacterial disease of sheep and goats. The disease is caused by Corynebacterium pseudotuberculosis.

CLA is notifiable in NI under the Diseases of Animals (Northern Ireland) Order 1981 and any suspicious signs should be reported to the local Divisional Veterinary Office.

This will provide information about the occurrence of the disease.  Current policy is that no restrictions will be placed on the reporting flock.

What are the clinical signs?

The main clinical signs of CLA are abscesses in the lymph glands and chronic wasting.

How is CLA spread?

The bacterium enters the body through inhalation or penetration of wet or wounded skin whereupon it travels to the nearest lymph gland. Sheep gathered together present the highest risk of spread when infected sheep cough or via soil contaminated with pus. It is also possible that contaminated shearing equipment transmits the bacterium.

Prevention of CLA

Carrier animals, mainly rams, introduce most new infections and flock owners should take the following preventative measures:

  • flock owners should examine purchased stock looking in particular for evidence of scarring around the heads of rams and ram lambs
  • isolate purchased stock as long as possible (a few weeks minimum)
  • isolate suspect cases
  • observe strict hygiene practices when dealing with suspect or confirmed cases i.e. clean and disinfect equipment, destroy potentially infected bedding
  • clean and disinfect clipper blades between sheep. Treat any nicks/cuts with antiseptic
  • wait 2 weeks between clipping and dipping to ensure all skin wounds are healed
  • maintain good hygiene during lambing, docking and castration
  • ensure good personal hygiene. There have been a few cases in humans where lymph glands have become infected

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