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

Animals that have an inconclusive skin test result at two consecutive tests (known as 2xIRs) are also classified as reactors. Read more about inconclusive reactors on the TB hub. Any reactors found during a skin test will be 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 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.

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.

Isolation of reactor animals

Reactors must be immediately isolated from the rest of the herd as far as practically possible to reduce the risk of spread of TB within the herd. If IRs are found at the same test they must be also be isolated, separately from any reactors if possible, as they will be re-tested. You should ensure that:

  • Adequate isolation facilities are available – ideally a dedicated building separate from any other cattle buildings but a separate paddock where nose-to-nose contact with other livestock can be prevented is acceptable. If a paddock is used, it must not be grazed by other cattle for at least 60 days after the reactor animal is removed
  • Isolated cattle have no nose-to-nose contact with other cattle
  • Where possible, air space, drainage and manure storage should not be shared with other cattle and separate equipment should be used for the isolated cattle
  • Reactor cattle should be milked last and their milk must be withheld from the bulk tank. If milked in the parlour, feed troughs, equipment and the areas of the milking parlour the reactor has been in contact with should be cleaned and disinfected afterwards each time with a Defra approved disinfectant for TB

If you are unsure how best to isolate the affected animal in your situation, for example, a suckler cow with a calf at foot, please contact APHA for advice.


Missing Animals

It is an important part of TB disease control that all eligible animals are TB tested.

Missing animals flow chart

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.

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  


Document Information

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  


Document Information

New 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  



Licence 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.