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 TB surveillance testing regime of herds in the LRA.

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 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.

All herds fully or partially located within a 3 km radial zone in the LRA are eligible for radial testing, except Licensed Finishing Units (LFUs).


As above, all herds fully or partially located within a 3 km radial zone in the LRA are eligible for radial testing, with no exceptions other than for LFUs. However, if you can provide strong evidence that none of the land within a 3 km radial zone is or has been used by your cattle, then, exceptionally, APHA will consider cancelling the radial test and re-instating your herd’s routine surveillance testing regime. If you can provide evidence of non-eligibility you must contact APHA and request a Radial Testing Non-eligibility Declaration Form (TR473), which will need to be countersigned by your private vet. APHA will supply you with a list of field numbers that link your holding to the radial zone and you must supply evidence (detailed in the form) that those fields have not been used by your cattle and will not be used for the foreseeable future (for at least 18 months). APHA will assess any evidence provided and its decision regarding eligibility is final.

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 in the LRA requires that the eligible herds complete a sequence of 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 will revert to their normal frequency of routine TB surveillance testing (i.e. every four years for the vast majority of cattle herds in the LRA).

Yes. Herds undergoing radial testing are notified in writing by APHA of the change to their routine herd testing frequency, from four-yearly to annual, for the duration of radial testing regime. This means that pre-movement testing is required while the herd is subject to annual testing. Farmers have a period of four weeks from the date of the test notification letter from APHA to make arrangements, if needed, before the pre-movement testing requirement kicks in. Herds in the LRA that are already subject to annual surveillance testing due to their management / type of cattle enterprise (e.g. bull hiring premises or dairy holdings that commercialize raw drinking milk), will 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) and no skin test reactors were found.

A 3 km radial zone will be established around this new TB breakdown. If you have fields in the new overlapping radial zone, your herd will be eligible for further radial testing.

In this case, after the RAD12 has been carried out, the herd will resume its normal frequency of 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.