Radial TB testing in the Edge 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 annual testing sections of the Edge 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 annual 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 two 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.


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

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

From 1 January 2018, TB breakdowns with lesion and/or culture positive animals located in the following annual testing counties and part counties trigger radial testing:


  • Buckinghamshire
  • East Sussex
  • Leicestershire
  • Northamptonshire
  • Nottinghamshire
  • Berkshire (excluding the area of west Berkshire which is on six monthly testing)
  • Derbyshire (excluding the area of west Derbyshire which is on six monthly testing)
  • Hampshire (excluding the area of north-west Hampshire which is on six monthly testing)

The six-monthly testing regime applies, as the default testing regime across a border is for the more rigorous regime to apply.

Again, the six monthly testing regime applies, as the default testing regime across a border is for the more rigorous regime to apply.