Private non-validated or unapproved TB tests for cattle in England
Source: gov.uk (2025-02-03)

Private non-validated or unapproved TB testing in cattle carried out by private vets in England, conditions for testing and how to get permission from the Animal and Plant Health Agency (APHA).

Private vets must ask for permission from the Animal and Plant Health Agency (APHA) before carrying out any TB testing.

You must not do a tuberculosis test on an animal unless you have permission from APHA. You must report the test result immediately to APHA. This is set out in Article 10 of The Tuberculosis in Animals (England) Order 2021 (https://www.legislation.gov.uk/uksi/2021/1001/contents).

The only ante mortem tests currently approved for statutory cattle tuberculin (TB) testing in England are the:
- comparative intradermal tuberculin skin test
- supplementary interferon-y (IFN-y) blood test
An understanding of the performance of any diagnostic test is needed before it can be officially approved for routine veterinary use, usually following validation to the standards set out by the World Organisation for Animal Health (WOAH).

Private vets can carry out other non-validated or unapproved TB tests:
- with permission from the Animal and Plant Health Agency (APHA)
- on an exceptional basis
This applies to any TB test other than the skin and IFN-y tests cited in current EU legislation.

Non-validated or unapproved TB tests cannot be used to replace the current statutory TB testing regime.

Private vets can also consider using the IFN-y test on a voluntary basis, at the herd owner’s expense, if:
- a herd does not qualify for mandatory IFN-y testing
- APHA will not pay for the test on a discretionary basis
Read the guidance on private IFN-y testing (https://www.gov.uk/guidance/private-interferon-gamma-ifn-y-testing-for-bovine-tuberculosis-tb-in-england).

What non-validated or unapproved tests can be used for

These tests can only be used to identify additional infected animals in herds with chronic TB breakdowns with lesion and/or positive PCR (or culture) cattle that have not been resolved by repeated short interval skin testing or IFN-y parallel testing.

They cannot be used to negate or question positive results to official tests on animals awaiting slaughter that are:
- skin test reactors
- IFN-y test positive
Non-validated or unapproved TB test types

There are 2 categories of unofficial tests for TB in individual cattle herds:
- WOAH-validated kits such as the IDEXX ELISA and the Enferplex TB antibody test
- novel, semi-experimental assays that have not been validated in cattle, such as the Polymerase Chain Reaction (PCR) on faecal samples and the Actiphage blood assay
The IDEXX ELISA test for M. Bovis

The bovine IDEXX ELISA antibody assay (IDEXX Laboratories, Maine, USA) can be used to measure circulating antibodies in cattle with advanced M. bovis. It is approved by WOAH to supplement the skin test for detection of TB-infected cattle and it was added to WOAH’s Register of Validated Diagnostic Kits (https://www.oie.int/en/scientific-expertise/registration-of-diagnostic-kits/the-register-of-diagnostic-kits/) in June 2012. It’s performed at APHA Starcross.

Antibody assays are not currently approved for official, regular TB testing of bovine animals in England. However, APHA may use the IDEXX ELISA test as a third-line test in exceptional circumstances in for herds that have chronic or persistent TB breakdowns that have not resolved after already been through:
- multiple rounds of short interval skin testing
- the IFN-y parallel test
Supplementary IDEXX testing carried out by APHA in England requires prior consent and a written agreement from the owner to allow the removal of any TB seropositive animals, with statutory compensation payments.

The IDEXX ELISA is a relatively simple and inexpensive assay that uses a combination of 2 M. bovis recombinant antigens (MPB83 and MPB70) that can provide test results in 2 hours and has:
- a moderate test sensitivity of 65%
- a specificity of 98% in cattle
To achieve maximum sensitivity in this test, a prior TB skin test must be performed. APHA then requires that blood samples for government-funded IDEXX testing are taken for 10 to 30 days following the skin test.

The Enferplex test for M. Bovis

The Enferplex TB test is another antibody test for TB in cattle that was validated to WOAH standards more recently (Enfer Diagnostics). This test achieved WOAH approval and was added to WOAH’s Register of Validated Diagnostic Kits (https://www.oie.int/fileadmin/Home/eng/Our_scientific_expertise/docs/pdf/OIE%20Abstract%2026.07.19.pdf) for the detection of TB in cattle in May 2019.

This test is currently not approved by Defra, Scottish and Welsh Governments for official government-funded supplementary antibody testing of cattle. It can be used on a private basis in England subject to prior permission from APHA.

The Enferplex TB test is a ‘multiplex’ enzyme immunoassay designed to detect the presence of antibodies to an array of 11 M. bovis antigens. Any antibodies present in serum (and potentially milk) samples are detected simultaneously by a multiplex immunoassay.

Information in the WOAH data sheet indicates:
- a high test sensitivity of 71.4% (non-boosted) and 94.2% (boosted by a prior intradermal injection of tuberculin)
- a specificity of 99.7% for this test using a high specificity setting
As for the IDEXX test, the highest sensitivity of the Enferplex TB test is also dependent on a prior tuberculin skin test, which triggers the anamnestic (memory) antibody response in infected cattle. APHA strongly recommends that blood samples for Enferplex testing of cattle are taken within 10 to 30 days following a skin test.

Conditions for getting permission to test

You must get permission from APHA before carrying out any private non-validated or unapproved TB test.

APHA will only give permission for the test if the:
- herd has undergone mandatory IFN-y testing (if the herd is eligible under current Defra policy)
- herd owner has given informed, written consent
Informed consent from herd owners

Before testing, the private vet must get written consent from the herd owner to show they have informed them that:
- the tests are not validated or approved by Defra for routine use in cattle
- the test results may be unreliable and difficult to interpret, meaning the test may not offer any certainty about the animals’ true infection status’
- the animals become positive after a subsequent government-funded TB test
- APHA considers it necessary to remove the animals as a direct contact
- under licence to slaughter directly via a slaughter gathering
- to a veterinary research centre for post-mortem examination
- to an Approved Fishing Unit (AFU)
- the herd owner must privately slaughter any animal that tests positive to a private IDEXX ELISA or Enferplex TB test, before APHA will restore the Official TB Free (OTF) status of the affected herd
How to get permission to test

Private vets must use application form PRIV03 (https://www.gov.uk/government/publications/private-use-of-non-approved-tests-for-tb-in-cattle-in-england) to apply to APHA for permission to test. The form must be submitted at least 10 working days before the intended date of sampling

Email the form to xxx@xxx.xx (mailto:xxx@xxx.xx) for the attention of the APHA case or duty veterinarian.

The form must include:
- what animals will be tested
- what type of samples will be taken (for example, blood, milk, faeces, bulk milk)
- what tests will be used and when
- the current known performance of the tests, such as published articles or access to proof-of-concept data
- how the tests will contribute evidence needed to validate the tests (for example, by collaboration with the manufacturer)
- whether a Home Office licence is required and if it has been obtained
- what will be done with the results
- how APHA will be kept informed
Private vets must also submit application form PRIV02 (https://www.gov.uk/government/publications/private-tb-interferon-gamma-ifng-testing-of-cattle-in-england) if they want to carry out any additional private IFN-y tests in conjunction with the non-validated or unapproved test.

Engaging with APHA

APHA expects private vets to engage with the test manufacturer so use of the tests can contribute to the evidence needed to validate the tests.

APHA TB diagnostic experts, and the APHA case veterinarian, may be able to offer advice on how to use the tests where APHA has been involved from the outset.

If the herd owner has given written authority to share their information, the APHA case veterinarian will discuss the application with the private vet. This will include the previous test history of the herd and its eligibility for IFN-y testing.

The private vet must give evidence to APHA that shows a Home Office licence has either been obtained or is not needed. For example, blood samples taken at the time of IFN-y testing (or other disease screening) may require a licence for scientific research unless it was agreed with the Royal College of Veterinary Surgeons (RCVS) that it formed a legitimate part of a disease control intervention that was covered by the Veterinary Surgeons Act.

Test results

The private vet must report test results to APHA immediately after every testing event. The report must also include any planned management of tested animals (for example, by sorting into epidemiological groups).

Under the Tuberculosis in Animals (England) Order 2021 it’s a legal requirement to report suspicion of TB in an animal. This legislation also allows APHA veterinarians to issue a notice that restricts the use of a cow’s milk if the animal is a TB suspect.

What happens if privately-tested animals have positive results

Animals that have tested positive to a non-validated or unapproved test cannot be sold, except to slaughter.

Culling of test-positive animals must be a voluntary decision by the owner, and the owner must pay for any associated costs. No compensation will be available.

Regaining OTF status for TB breakdown herds

TB breakdown herds that have completed the normal APHA testing protocols to lift movement restrictions, but which contain one or more IDEXX or Enferplex positive animals, will not be able to regain OTF status and move cattle free without an APHA licence until either of the two following criteria apply.

Criteria 1

All the IDEXX or Enferplex positive animals have been privately culled or sent to an approved finishing unit (AFU), and APHA’s approval to carry out private non-validated TB testing has been withdrawn.

Criteria 2

All cattle in the herd that are over 42 days old (including IDEXX or Enferplex positive animals) have passed a comparative skin check test carried out by APHA 6 months after the herd would have been eligible to regain its OTF status. This must be supplemented with a private IFN-y parallel test of the remaining IDEXX or Enferplex positive animals, funded by the owner.

APHA will remove any of the IDEXX or Enferplex positive animals (with compensation) and breakdown and restrictions will continue, if either:
- any of those animals yield a positive reaction to bovine tuberculin on the skin test (irrespective of the avian reaction)
- any of those animals give a positive result on the private IFN-γ test
If a private IFN-y test was agreed in advance with APHA, and conducted at an APHA-approved laboratory (or similar), any positive animals will be:
- compulsory slaughtered with statutory compensation
- subjected to post-mortem inspection
- sampled for culture if necessary
If all of the cattle in the herd pass the skin and gamma tests, APHA will restore the OTF status of the affected herd

Once the herd has regained its OTF status, APHA’s approval to carry out private non-validated or unapproved TB testing will automatically end. A new application will be required for any further testing.

Milk from test-positive dairy cows

Milk from dairy cows that have tested positive to a non-validated or unapproved test can enter the human food chain.

Milk from these animals will be subject to pasteurisation while the herd is under TB restrictions.