Actions when a TB reactor is found

This guidance applies in England

England flag - TB hub

A reactor is an animal that has failed a test for bovine TB. This may be the skin test, the interferon-gamma blood test or any other authorised test for TB.

Skin test reactors

Animals that have an inconclusive skin test result at two consecutive tests (known as 2xIRs) are also classified as reactors. Any reactors found during a skin test are marked immediately using a DNA tag inserted into the animal’s ear. This is a special tag that takes a small tissue sample from the ear of the animal when inserted. This tissue sample is stored and can be DNA tested by the Animal & Plant Health Agency (APHA) at random or when fraud is suspected, and cross checked against the DNA of the animal sent to slaughter. This ensures that the correct animal is compulsorily slaughtered.

Viles of Avian and Bovine Tuberculin - TB hub

Gamma test-positive animals

For animals that are positive to the gamma test, the procedure is different. APHA will notify the keeper in writing of the ear tag numbers of animals that are positive to the test, and it is the keeper’s responsibility to identify and isolate these animals pending their removal to slaughter. 

The same applies in circumstances where animals that are classified as reactors as a result of later re-interpretation of a skin test by APHA. For example, an animal’s skin test result is clear at a test using standard interpretation, but the test is later re-interpreted using severe interpretation and the animal becomes a severe reactor and is removed.

Vet holding a sample in a cattle shed - TB Hub

Missing Animals

Young cows on a rainy day - Bovine TB

It is an important part of TB disease control that all eligible animals are TB tested. If an animal hasn’t been presented for TB testing due to it being either dead or not at location, its British Cattle Movement Service (BCMS) record will be checked by APHA. If there is a discrepancy with the record then APHA will send you a letter asking you to check and update your records and resolve the discrepancy with BCMS.

Missing animals can extend the time that your herd is under TB restrictions, so it’s important to make sure that all your records are up-to-date. If you claim Basic Farm Payment, then it could affect your payments if discrepancies are not corrected and TB testing becomes overdue.

Policy - Bovine TB

What documents and further information will I receive?

As well as some more general documents, you will receive a reactor pack in the post which contains information and guidance on what you need to do next. You will also receive a valuation pack with the valuation of your reactor animals and documents relating to their removal to the slaughterhouse.

General documents


Automatic Animal and Public Health Restrictions after a Reactor or Inconclusive Reactor is found at an Official Diagnostic Test for Tuberculosis (TB) in Cattle, Buffalo or Bison

  • This information note should be handed to you by your TB tester at the time of the test and it’s important that you read and understand it.
  •  It explains the actions you need to take now your herd is under movement restrictions, as well as public health advice for you and your family.
  • It contains a checklist that will help you prepare for removal of reactor animals to slaughter.

Reactor pack

TR35New Breakdown Letter – Reactors or Inconclusive Reactors found
  • This letter gives you the results of the skin test where reactors were found, and explains the next steps and actions you need to take.
  • It also lets you know that skin test results may be re-interpreted using severe interpretation. This may result in more animals being classed as reactors or inconclusive reactors (IRs).
  • For dairy herds, it also reminds you of the milk restrictions for TB-restricted herds.

Notice of Intent to Slaughter Bovine Animals

  • This notice is for information only and does not need any action from you.
  • It lists the total number of cattle identified as TB reactors and their ear tag numbers.
  • You need this document for any insurance claims.
TB24cLicence Authorising General Movement of Cattle to a Licensed Slaughterhouse
  • You need this licence to move clear tested cattle from your holding to slaughter whilst your herd is under movement restrictions.
  • This is a general licence and is valid for the duration of the TB breakdown until movement restrictions are lifted.
  • This licence is only for clear testing cattle. Reactors and IRs are issued with separate specific TB24 licences to slaughter.

Notice Requiring Cleansing and Disinfection

  • You need to clean and disinfect the area where the reactors were isolated with a Defra approved disinfectant for TB.
  • As far as possible, you must also clean and disinfect any other areas of your premises, vehicles, equipment and facilities that could have been contaminated with TB bacteria.
  • It’s important that you complete and return the BT05 declaration to APHA to confirm that this has been done.
  • For reactors isolated at grass, there is a specific tick box on the declaration.
  • If you do not return the declaration then APHA cannot lift movement restrictions and restore your herd’s OTF status at the end of the breakdown.
  • If you can’t find the original BT05 sent to you in the reactor pack, you can download a copy from GOV.UK