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What is the protocol for rehabilitating badgers?

20 June 2019, at 9:00am

Consideration should be given to bovine tuberculosis when it comes to treating badgers for release back into the wild

Around 400 badgers (Meles meles; Figure 1) are rehabilitated and released in England each year. This includes adult badgers, frequently admitted for reasons of anthropogenic trauma, and orphaned or abandoned badger cubs.

Approximately 36 percent of adult badgers are suitable for treatment, rehabilitation and release. Common reasons for presentation include: road traffic collisions (37 percent) (Figure 2), “territorial” conspecific wounds (55 percent) (Figure 3), old and/or diseased, and illegal digging, baiting, trapping and snaring injuries. Approximately 60 apparently abandoned and orphaned badger cubs are raised annually (Figure 4). These are usually clinically well but require a prolonged rearing and rehabilitation process before they can be released.

In common with other British wildlife species, there is no formal regulation of badger rehabilitation. Badgers are well protected in the wild (under the Protection of Badgers Act 1992); however, it is legal to bring these animals into captivity if they are injured, or dependent neonates, and treat them with the intention of eventually releasing healthy animals back to the wild. Once captive, badgers are protected under the Animal Welfare Act 2006.

Bovine tuberculosis precautions

Bovine tuberculosis (bTB) is a disease in cattle caused by Mycobacterium bovis infection. M. bovis can affect a wide range of species, including humans, cattle and badgers. Both cattle and badgers, in common with other wild mammalian species, suffer from the disease. Infected badgers are able to maintain and spread infection. Excretion of bacteria may occur in saliva, urine, faeces and lymph node abscesses. Badgers may also transmit infection, via contaminated saliva, during social disputes that result in wounding (Figure 3).

Clinical signs of tuberculosis in badgers, as in other species, are typically weight loss leading to emaciation, although a variety of other clinical signs may be seen related to localisation of infection in the lung, pleural cavity, liver, spleen, kidney, lymph nodes and growth plates of long bones.

Those dealing with badgers in a rehabilitation situation must be aware of the possible risk of M. bovis infection, both to themselves and their staff and to other animals, and take appropriate precautions. Good practice would include the use of recommended PPE (gloves, aprons, masks) – especially when dealing with badger urine, faeces, saliva and wounds; cleaning with a Defra-approved disinfectant for M. bovis; and avoiding high-risk procedures such as post-mortems outside of approved laboratories.

The Defra Strategy for achieving Officially Tuberculosis Free Status for England 2014 does not specifically mention badger rehabilitation; however, this activity has raised concerns with farmers.

In 2017, Defra and wildlife groups cooperated to update the Badger Rehabilitation Protocol, first published in 2003, and produced a new edition in 2018. The protocol provides guidance about how badgers should be handled, cared for, rehabilitated and released (Figure 5). Disease prevention is at the core of the protocol and appropriate controls for M. bovis infection, including testing of badgers, are detailed. This guidance reduces zoonotic risks for individuals handling badgers, and the risk of disease transmission to other animals, including livestock. Maintaining the confidence of landowners providing release sites for badger cubs is key to rehabilitation.

FIGURE (5) Guidance on how badgers should be handled, cared for, rehabilitated and released. Adapted from the Badger Rehabilitation Protocol (Mullineaux (ed.), 2018)
FIGURE (5) Guidance on how badgers should be handled, cared for, rehabilitated and released. Adapted from the Badger Rehabilitation Protocol (Mullineaux (ed.), 2018)

TB testing

In common with other species, the availability of commercial tests with high sensitivity and specificity for M. bovis infection in badgers is very limited. The Dual Path Platform (DPP) VetTB assay (Chembio Diagnostic Systems) is a serological test, available from the APHA laboratory at Starcross, that measures the specific antibody response to antigenic targets MPB83 and ESAT6/CFP10. The test in badgers has a relatively low sensitivity (55.3 percent) but is highly specific (97.5 percent). Testing an individual animal with a blood test on more than one occasion increases the sensitivity of the test but reduces test specificity. If badgers are tested on three occasions with DPP, point estimates are a sensitivity and specificity of 91.1 percent and 92.7 percent respectively, though these will vary with stage of disease and degree of pathology.

No routine testing of adult badger casualties is carried out under the Badger Rehabilitation Protocol, as adult animals are maintained in isolation during captivity and released exactly where they were found for both territorial and disease prevention reasons. A single test is considered sufficiently sensitive and these animals are not in captivity long enough to allow for multiple testing. Adult badgers with clinical tuberculosis should be easily recognised by veterinary surgeons and these animals should be immediately euthanised.

FIGURE (6) The protocol for testing badger cubs. Adapted from the Badger Rehabilitation Protocol (Mullineaux (ed.), 2018)
FIGURE (6) The protocol for testing badger cubs. Adapted from the Badger Rehabilitation Protocol (Mullineaux (ed.), 2018)

Preparing badgers for release

Badger cubs wean late and are bottle fed until they are 10 to 12 weeks old before being rehabilitated in groups (Figure 7) for behavioural and social reasons. These groups must eventually be released at a new location, so any disease risk associated with translocation must be mitigated against.

Badger cubs are tested using DPP on three occasions prior to release to maximise test sensitivity. Badger cubs testing positive to any one of the three tests are euthanised and sent for post-mortem examination and M. bovis culture. The outcome for remaining cubs in the group is determined by these findings; those in contact with a confirmed positive animal are euthanised (Figure 6). Cubs are released, with full landowner consent, into specially constructed artificial setts in Defra classified areas of similar bTB status in cattle (“low”, “edge”, “high”) to where the cubs originated.

Badger cubs are BCG vaccinated prior to release (Figure 8), usually at the time of the third blood test. BCG vaccine has been shown to reduce the severity and progression of M. bovis infection in badgers. The benefits of BCG are, however, best seen on a population basis where groups of badgers, such as cub groups, are vaccinated. In adults, there is an argument that vaccination of an individual is of limited benefit, unless the other badgers in the area or group are also vaccinated. Where vaccination of adults prior to release is possible, no disadvantages are evident

References
Author Year Title
Mullineaux, E. 2016 Badgers. In: BSAVA Manual of Wildlife Casualties, 2nd ed. Mullineaux, E. and Keeble E. (eds). BSAVA Publications, Gloucester, pp. 210-227
Mullineaux, E. 2018 Badger Rehabilitation Protocol
Mullineaux, E. and Kinder, P. 2011 Managing public demand for badger rehabilitation in an area of England with endemic tuberculosis. Veterinary Microbiology, 151, 205-208

Elizabeth Mullineaux, BVM&S, DVM&S, CertSHP, MRCVS, is an RCVS Recognised Specialist in Wildlife Medicine (Mammalian). She is Scientific Advisor to Secret World Wildlife Rescue and has a clinical doctorate in badger rehabilitation and release. Liz is co-editor of the BSAVA Manual of Wildlife Casualties and author of several publications on wildlife medicine

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