TB in cattle

AHVLA investigates all incidents of suspected notifiable disease. If you suspect signs of a notifiable disease, you must immediately notify your local AHVLA Field Services.

The risk to your animals


Tuberculosis (TB) is a serious disease of warm-blooded mammals arising from infection by Mycobacterium tuberculosis (MTB) complex. This is part of a group of closely related bacteria that includes:

  • Mycobacterium bovis (M. bovis) (responsible for TB in cattle and other mammals)
  • M. tuberculosis (the primary agent of TB in humans)
  • M. bovis BCG (an attenuated strain of M. bovis used as a vaccine against human TB)

Bovine tuberculosis (bTB) is the disease in cattle that results from infection with M. bovis bacteria, and is one of the most complex animal health problems currently facing the farming industry in Great Britain. It is a notifiable disease and suspicion of the disease must be reported to your local AHVLA Field Services.

For further information on M bovis, see the Defra website.

Bovine TB is a chronic disease and it can take years to develop. M. bovis grows very slowly and only replicates every 12-20 hours. The lymph nodes in the animal’s head usually show infection first and as the disease progresses lesions will begin to develop on the surface of the lungs and chest cavity.

Due to the slow progression of infection, and the Government’s compulsory testing and slaughter programme clinical signs of bTB, such as weakness, coughing and loss of weight, are now rarely seen in cattle in GB. Most cattle herds are tested for bTB at least every four years which identifies most infected cattle before clinical signs of disease become apparent.

M. bovis can also infect and cause disease in badgers, deer, goats and many other mammals, including people. Cases or suspicions of bTB in other species should be notified to your local AHVLA Office, although there is no statutory routine testing programme for the disease in other species.

How is bovine TB spread?

There is still some uncertainty surrounding bTB and the way it is transmitted though it is spread primarily through the exchange of respiratory secretions between infected and uninfected animals. This transmission usually happens when animals are in close contact with each other. Bacteria released into the air through coughing and sneezing are inhaled by uninfected animals and the disease is able to spread.

Cattle to cattle transmission is a serious cause of disease spread which is substantiated by scientific evidence.

The evidence for a link between bTB in badgers and bTB in cattle was reviewed in 1997 by the Independent Scientific Review Group, led by Professor John Krebs.

Information leaflet: Understanding the risk of bovine tuberculosis to cattle from wildlife (PDF)

The disease may also be spread by contaminated equipment, feedstuffs and slurry.

Page last modified: 22 May 2014