Radial TB testing in the Low Risk Area of England

Radial testing diagram - Bovine TB

A targeted TB surveillance skin test carried out on cattle holdings around all new TB breakdowns with lesion and/or culture positive animals identified in the Low Risk Area.

The purpose of the test is to check for spread of TB to neighbouring cattle herds and to ensure that any undetected source of infection in the locality is identified, thus supplementing the routine surveillance testing regime in those herds.


All cattle holdings falling within, or straddling, a 3 km radius circle from the new (‘index’) TB breakdown farm are identified and required to undertake an immediate radial test of all the cattle on the holding aged 42 days and older. The radial testing regime is also be applied to cattle herds that are outside of the 3 km radius circle that have had regular direct or indirect contact with holdings within the 3 km radial testing area.

Cattle keepers receive a test notification letter from the Animal & Plant Health Agency (APHA) informing them that their herd requires an immediate radial test, specifying the date by which the test is due. The testing window for this immediate radial test usually starts upon receipt of this test notification letter.

Herds are not routinely placed under movement restrictions whilst undergoing radial testing. However, if an inconclusive reactor or reactor is found at a TB test, or lesions suspicious of TB are found in an animal sent to slaughter (known as a slaughterhouse case), then the herd is placed under movement restrictions as per standard APHA procedures. Normal overdue procedures also apply for the radial tests and restrictions will be issued if the test results are not received by APHA by the latest due date of the testing window.

Radial TB tests are paid for by the government.

The radial testing regime requires that the eligible herds complete three additional skin tests as outlined below:


  • Immediate radial test (RAD): this test is carried out after receiving the test notification letter from APHA, unless a whole-herd test has been completed with negative results within the 60 days before or after the index case (in such cases, the initial radial test is waived and a RAD6 test is scheduled for six months from the date of the last whole herd test).
  • RAD6 test, carried out six months after completion of the immediate radial test.
  • RAD12 test, carried out twelve months after the RAD6 test.


Thereafter, and provided all the tests are completed with negative results, herds revert to their normal frequency routine surveillance testing.

Yes. Herds undergoing radial testing are notified in writing by APHA of the change to their unit monitoring regime (UMR), from four-yearly testing to annual testing, for the duration of radial testing regime. This means that pre-movement testing is required while the UMR of a herd is that of annual testing. Farmers are given a period of four weeks from the date of the test notification letter from APHA to make arrangements, if needed, prior to commencement of the requirement for pre-movement testing. Herds in the LRA that are already on an annual UMR due to management or type of premises (e.g. bull hiring premises) continue to require pre-movement testing during the radial testing period.

Yes, provided it has been carried out at the right time (i.e. in the 60 days before the date of animals’ movement).

In this case, after the RAD12 has been carried out, the unit monitoring regime (UMR) of the herd will revert to its original one, resuming normal frequency routine surveillance testing. The requirement for pre-movement testing in those herds that were not subject to pre-movement testing prior to the radial testing regime will also cease to apply. These changes are notified in writing by APHA following review of the RAD12 test results.