Inconclusive reactor cattle in England

Inconclusive reactors (IRs) are animals that have a TB skin test result that is neither definitively clear nor positive. The animal shows a reaction to bovine tuberculin greater than the avian, but not strong enough to be classified as a reactor.

IRs are placed under movement restrictions and must be isolated from the rest of the herd until they are re-tested. The Animal & Plant Health Agency (APHA) issue a letter and restriction notice (TB34) for IRs which explains what keepers need to do. The soonest an IR can be re-tested is 60 days after the injection date of the previous test. IRs cannot move off the holding (e.g. to slaughter) except under a licence issued by APHA.

When one or more IRs are found, the herd is initially put under automatic whole herd movement restrictions until the test result is reviewed by the Animal & Plant Health Agency (APHA). For officially TB free (OTF) herds, the need for whole herd movement restrictions is assessed against the ‘three year rule’.

 

If the herd has had a TB breakdown in the three calendar years prior to the date the IR was found, and other criteria assessed by APHA are satisfied, then the three year rule applies. The whole herd movement restrictions (TB02) that were automatically imposed remain in place. The separate restrictions (TB34) that were imposed on the IR also remain in force until the animal is re-tested. 

If the three year rule does not apply, whole herd movement restrictions (TB02) that were automatically imposed are lifted and the holding is free to trade. The separate restrictions (TB34) that were imposed on the IR remain in force until the animal is re-tested. 

For IRs found where herd movement restrictions (TB02) are already in place, a TB34 isolation notice is served on the IR(s). You must isolate the IR(s) from the rest of the herd promptly. IRs identified at a short interval test (SIT) are re-tested at the next SIT. If the herd doesn’t require a further SIT, only the IRs are re-tested, but the whole herd movement restrictions (TB02) remain in place. 

IRs are re-tested a minimum of 60 days from the previous test. There are two possible outcomes:

 

  • Clear (negative) – the animal is known as a ‘resolved IR’ and may re-join the herd. In the High Risk Area (HRA) and Edge Area (and TB breakdown herds in the Low Risk Area), resolved IRs are restricted for life to the holding in which they were found (see below). 
  • Not clear (positive) – if the animal does not test negative (i.e. it is either a reactor or an IR again) it is classed as a reactor and compulsorily slaughtered.

Yes. You can choose to send an IR to slaughter at your own expense before it is re-tested. You must tell the Animal & Plant Health Agency (APHA), giving as much notice as possible, as they will have to issue a specific TB24 licence allowing the IR to travel to a slaughterhouse of your choice. IRs can only go direct to an abattoir, they are not permitted to go via a slaughter collection centre. APHA arrange for privately slaughtered IRs to undergo post mortem inspection in the slaughterhouse to look for lesions suspicious of TB, and tissue samples are taken for bacteriological culture.

 

Compensation is not paid for privately slaughtered IRs. Taking this option rather than waiting for the outcome of the IR’s next test could lead to additional testing and/or prolong the movement restrictions on your herd. If you are considering privately slaughtering one or more IRs, please contact APHA to discuss your case so that you are fully aware of the potential consequences and can make an informed decision.

If an IR dies on farm or has to be put down for welfare reasons, you need to inform the Animal & Plant Health Agency (APHA). You will not receive compensation for IRs that die on your farm. If an IR dies on farm or is privately slaughtered and post-mortem inspection reveals visible lesions suspicious of TB, APHA will apply whole herd movement restrictions (unless they are already in place) and test the rest of the herd.

Resolved inconclusive reactors (IRs)

A resolved IR is an animal identified as an IR at a TB skin test, which then tested clear upon re-test at least 60 days later. 

All IRs in the High Risk Area (HRA) and Edge Area (and in TB breakdown herds in the Low Risk Area) that have a negative result on re-testing remain restricted for the rest of their life to the holding in which they were found. The only permitted off movements for resolved IRs are to slaughter, either directly, or via an Approved Finishing Unit (AFU).

Yes. Scientific studies looking at resolved IRs in the Republic of Ireland where bovine TB is widespread, have demonstrated that such animals have significantly higher odds of becoming reactors at a subsequent test in the same or another herd. The studies concluded that;

 

  • Resolved IRs that moved out of the herd after passing their re-test were 12 times more likely to be disclosed as a reactor at the next test compared to all other animals in the national herd.
  • Between 11.8% and 21.4% of IRs slaughtered prior to re-test showed visible lesions suspicious of TB at post mortem meat inspection, compared with less than 0.5% of non-IR animals.

 

These studies provided evidence for the introduction of a new policy for resolved IRs in the Republic of Ireland in 2012. After reviewing the evidence, Defra introduced a similar policy in England.

 

Analyses of cattle herds in England in 2018 showed that over 40% of IR-only herds went on to have a TB incident within the following 15 months in the High Risk Area (HRA), with a substantial proportion similarly affected in the Edge Area (38%).  This indicates that IRs are an important predictor of the presence of TB infection and supports the policy to restrict resolved IRs for life to the herd in which they were found. Further research has been carried out exploring the risk posed by IRs in England and Wales, which adds to the evidence from similar studies conducted in the Republic of Ireland. This latest research found that the odds of an animal becoming a subsequent reactor during the study period were greater for IR animals than for negative testing animals in the HRA and Edge Area of England, and in Wales.

Slaughtering all IRs would be disproportionately costly. Increased numbers of TB-free cattle would be slaughtered resulting in additional herds being unnecessarily placed under movement restrictions.  Accepting that risk can never be completely eliminated, the policy aims to reduce the risk to an acceptable level with the resources available to the Government.

No, not necessarily. Keepers can send an IR to slaughter privately, before they are re-tested, under a licence from the Animal & Plant Health Agency (APHA). Keepers wishing to privately slaughter an IR must contact APHA to discuss the implications and obtain a licence to move the animal to slaughter.

It is the keeper’s responsibility to ensure resolved IRs are restricted for life to the holding in which they were found. If a keeper intends to retain resolved IRs in their herd it is advisable, but not mandatory, to physically identify them to prevent their accidental movement off the holding.  This can be achieved by using a management tag or freeze brand and/or marking the animal’s passport.  It is also advisable to keep a record of any resolved IRs in the herd register.

A restriction notice is issued explaining the conditions of the restrictions and the keeper’s obligations.

Potentially, yes. Cattle keepers can commission interferon-gamma blood testing of resolved IRs at their own cost.  The keeper must first seek permission from the Animal & Plant Health Agency (APHA) through their private vet. The blood sample must be collected on or after the injection date (day 1) of the clear IR re-test.   

 

If the resolved IR tests negative to the gamma test, the animal is free to move off the holding, unless it is subject to any other whole herd movement restrictions. If the animal tests positive, it is compulsorily slaughtered (with compensation paid), movement restrictions are applied to the whole herd (if not already in force), and standard TB breakdown procedures followed.

Animals less than six months of age are excluded from gamma testing as their immune systems are still developing and this can interfere with the test, leading to false positive results. If a resolved IR is too young for a gamma test, the keeper may apply to the Animal & Plant Health Agency (APHA) to defer the test until the animal becomes old enough. The keeper or their private vet must contact APHA to discuss the situation and all cases will be assessed on an individual basis.

A resolved IR in a TB-restricted herd undergoing government-funded mandatory gamma testing will automatically be included in any whole herd testing as long as it is over six months of age. If the resolved IR tests negative to the gamma test then the restrictions on the animal are lifted, though it would continue to be subject to whole herd movement restrictions. If the resolved IR tests positive to the gamma test, it is compulsorily slaughtered with compensation paid, just like any other reactor.

Yes. Resolved IRs are permitted to move to slaughter directly or via an approved slaughter gathering. If your herd is officially TB free, you don’t need to apply to APHA for a specific licence. The general licence is available to view and download from GOV.UK. Although a copy of the general licence doesn’t need to accompany the cattle, you should familiarise yourself with the conditions before moving the animals to slaughter. Resolved IRs in TB breakdown herds are sent to slaughter using the licences issued to you by APHA, for example the TB24c general licence to slaughter.

Yes. Resolved IRs can be moved to an Approved Finishing Unit (AFU) either directly or via a TB dedicated sale (orange market). If your herd is officially TB free, this move can take place using the general licence available on GOV.UK. Although a copy of the general licence doesn’t need to accompany the cattle, you should familiarise yourself with the conditions before moving the animals. Resolved IRs in TB breakdown herds can be sent to an AFU or TB dedicated sale subject to particular conditions.  You will need to apply to APHA for a specific licence.

Temporary CPH (tCPH)
Resolved IRs found at a tCPH are restricted for life to the permanent CPH associated with the tCPH. The resolved IR is only permitted to move back to the permanent CPH associated with the tCPH, or to slaughter either directly or via an Approved Finishing Unit (AFU).  Once back at the permanent CPH, the animal is restricted for life to that CPH.

 

Temporary Land Association (TLA)
If a resolved IR is found at a TLA it is restricted to the permanent CPH associated with the TLA. Subsequent movements of the resolved IR to the TLA are permitted, as by definition the land falls within 10 miles of the permanent CPH. For more information on livestock movements, tCPHs and TLAs see the Defra guidance.

If a resolved IR is found whilst at common grazing it is restricted for life to the keeper’s home holding, which must have a permanent CPH number. The resolved IR is not permitted to move to common grazing again because of the increased risk it potentially presents to other cattle herds that use the common land.

No. Resolved IRs are restricted to the holding in which they were found for the rest of their life and cannot move off to agricultural shows.

Yes. Resolved IRs can move off the holding for veterinary treatment under a licence issued by the Animal & Plant Health Agency (APHA). After treatment the animal must return directly to the home holding or to slaughter.

APHA carries out percentage checks of resolved IRs to ensure that they remain restricted for life. Non-compliances are referred to the relevant Local Authority for investigation and any enforcement action they deem appropriate.