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What is bovine TB?

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Bovine TB is a disease which can affect a range of mammals including cattle, badgers, deer and humans.

TB in cattle is caused by the bacterium Mycobacterium bovis. It can affect humans as well as animals but the risk to public health is kept low through regular testing of cattle, milk pasteurisation and inspections at abattoirs.

How it can spread

TB is mainly a respiratory disease of cattle. Disease spread between infected and uninfected animals is most likely to occur during periods of close contact, particularly when cattle are housed. The bacterium can also enter the body through ingestion and infection can be present in muck and slurry, milk and sometimes urine. In the UK clinical signs are rarely seen because cattle are removed before they develop any signs of illness. The signs can include:

  • chronic coughing
  • mastitis
  • weight loss.

Following infection it may be many months or years before the disease becomes apparent. Infected cattle can spread infection long before they show any sign of being unwell. The control and eradication of the disease relies on the early detection and removal of infected animals before they become ill. 


Wildlife, such as badgers, can also be infected and cattle and badgers can infect each other. Direct contact between badgers and cattle at pasture is thought to occur infrequently but badgers visiting farm buildings can be more of a disease risk. 

Other animals

Although the disease primarily occurs in cattle and badgers, it also affects other domesticated animals and wildlife such as:

  • camelids (llamas, alpacas, guanacos and vicunas)
  • deer
  • goats
  • sheep
  • pigs
  • wild boar
  • cats
  • dogs.