An inconclusive reactor (IR) is an animal with a TB skin test result that is neither clear (negative) nor positive. The animal shows a positive reaction to bovine tuberculin greater than to the avian tuberculin, 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 (TB02) until the test result is reviewed by 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 with lesion and/or culture positive animals in the three calendar years prior to the date the IR was found and other criteria apply, the whole herd movement restrictions (TB02) that were automatically imposed remain in place. If the three year rule does not apply, whole herd movement restrictions (TB02) that were automatically imposed are cancelled by a separate restriction notice (TB34) that is imposed only on the individual IR(s) and the rest of the herd is able to continue to trade. This remains in force until the IR(s) are re-tested.
For IRs found where whole herd movement restrictions (TB02) are already in place (e.g. in a TB breakdown situation), a TB34 isolation notice is served on the individual IR(s). You must isolate the IR(s) from the rest of the herd promptly and from any reactors found, if possible. Any IR(s) 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 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 re-test will not lead to movement restrictions being automatically lifted and could lead to additional testing in 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.
For unrestricted herds in England in 2019 that had surveillance tests disclosing IR(s) in the absence of reactors (IR-only herds), 40% of the ones in the HRA, 33% in the Edge Area, and 23% in the Low Risk Area (LRA) went on to have a TB incident (with or without lesion and/or culture positive animals) within the following 15 months. In around half of these cases the incident was detected at the IR retest in the HRA and Edge Area (82% of cases in the LRA). So, we know that IRs definitely pose a TB risk to the rest of the herd, however it’s not straightforward to quantify this risk for individual herds. National or regional estimates of TB risk can be misleading since the likelihood of an IR becoming a 2xIR or reactor will vary from animal to animal depending on factors such as
- the location (bTB risk area) of the affected farm
- the TB history and status of the cattle herd
- the origin and TB testing history of the animal
- the size of the skin reaction to bovine tuberculin etc.
You should discuss the specific risk posed by IR(s) in your herd with your vet so that you can make an informed decision about their management. Ultimately it is best to be proactive and identify disease at an earlier stage so that you can deal with it quickly and prevent it spreading.
You have the option to privately slaughter an IR before its re-test, however there are consequences for the rest of the herd which need to be considered (see FAQ above on private slaughter of IRs). Another option available to support the decision making process is to conduct a private interferon-gamma blood test. If the test result is negative, this may provide you with additional information and assurance about the infection status of the IR animal to assist with decision making. If the test result is positive, your herd would be placed under movement restrictions, the reactor compulsorily slaughtered with compensation paid, and normal breakdown procedures would apply. If you are considering private gamma testing then you should first discuss it with your vet, who will need to apply to APHA on your behalf for authorisation. More information about private gamma testing is available on the APHA vet gateway.
If an IR dies on farm or has to be put down for welfare reasons, you need to inform 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 or there’s a positive culture result, 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 within six months of passing their re-test were 12 times more likely to be positive at the next test or slaughter compared to all 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 0.3% of non-IR animals.
- During the study period, the time to detect TB in resolved IRs was 78% shorter, on average, compared to clear-testing cattle.
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 in 2017. Further research has been carried out exploring the risk posed by resolved IRs in England and Wales, which adds to the evidence above. This latest research found that the odds of a resolved IR becoming a subsequent reactor during the study period were seven and nine times greater than for negative testing animals in the HRA and Edge Area of England, respectively. The increased risk of becoming a reactor supports the policy to restrict resolved IRs to the herd in which they were found for life. At herd level, the time interval before a new TB breakdown in IR-only herds (those with IRs only and no reactors) in England and Wales was around half that of herds with a negative whole herd test. The hazard of a subsequent TB breakdown was 2.7 times greater for IR-only herds compared with clear herds in year one, after accounting for the influence of accepted risk factors of TB. Analyses of cattle herds in England in 2019 showed that in the High Risk Area (HRA), 40% of IR-only herds went on to have a TB incident (with or without lesion and/or culture positive animals) within the following 15 months (33% in the Edge Area). References in this FAQ can be accessed on the resolved IRs page.
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 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 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 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 general licence to slaughter (TB24c).
Yes. Resolved IRs can be moved to an Approved Finishing Unit (AFU) either directly or via an approved 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 approved 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 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.