The rescue, treatment, rehabilitation and release of wildlife serves three important purposes. Firstly, it provides an opportunity to learn about wildlife and our environment. Secondly, it may contribute to the conservation of species. Finally, and probably most importantly, it addresses the welfare of an animal that may be suffering from injury or illness or has been orphaned. It is our duty as decent human beings (and certainly as veterinarians and wildlife professionals) to relieve the suffering of animals. This may be as simple as providing first aid or facilitating euthanasia. It is essential, however, that attempts at relieving suffering do not perpetuate an animal’s suffering. For a wild animal, simply being in the presence of a human being, or being placed in a confined foreign environment, may induce suffering. This is an important consideration and one of the key factors that influence differences in ones approach to management of injured wildlife compared with domestic animals.
Caring for wild animals provides an opportunity to learn more about their biology, natural history, habitats, abundance, behaviour, husbandry and care. It inspires people to develop compassion and an understanding of our wildlife and our natural environment. It educates people, and it is perhaps through this that wildlife rescue and rehabilitation contributes most to the conservation of wildlife and the environment. Despite the many benefits, it is rare that the rehabilitation and release of an individual animal contributes directly to the conservation of a species. However, this may well be the case in situations where a population is so critically endangered that each individual is crucial to its survival. Rehabilitated animals may contribute to reintroduction programs, reinforce or supplement existing populations and can be a powerful tool for conservation (IUCN 2000; Woodford 2001).
Veterinarians have several key responsibilities with respect to the rescue, treatment, rehabilitation and release of wildlife. These include animal welfare, disease risk assessment and management, human health protection and provision of euthanasia and appropriate legal advice. They must also maintain accurate records, assist with wildlife emergencies and become involved in policy development. They also have a responsibility to provide sound, rational and scientifically based advice to various groups, from members of the public to politicians. Frequently, wildlife agency personnel are trained biologists who generally consider the dynamics and welfare of populations and ecosystems as a greater priority than the individual. They therefore frequently dismiss the perspectives and expertise of wildlife carers who focus on the individual. Conversely, wildlife carers frequently do not appreciate the mandate and responsibility of wildlife agencies toward population management. This may result in strained relationships between these groups (Clark 2002). Veterinarians are well placed to act as mediators in these situations.
Decisions to treat and rehabilitate wildlife must be based on a sound practical knowledge of veterinary medicine, individual and population biology and ecology, disease risks and legal requirements. Other issues must also be considered to ensure the ongoing welfare of the individual (during rehabilitation and after release), to avoid disappointment after emotional attachment to individual animals by carers and to protect wild populations and ecosystems (Sikarskie 1992).
1 ANIMAL WELFARE
The welfare of an injured, sick or orphaned wild animal must be considered from the time of rescue until well after release. A wild animal is already likely to be suffering a degree of stress or pain when it is first discovered and determined to be in need of assistance. To be approached and handled by a human invariably compounds this. It is crucial that appropriate and humane methods are employed to accomplish the capture of the animal. In some cases veterinary assistance may be required to facilitate capture, for example, if the animal needs to be darted. Initial care and first aid may take place in situ as, for example, with stranded, entangled or trapped marine mammals or other species. Immediate intervention, with or without first aid, may be all that is required and the animal can be released or, if indicated, euthanased immediately. Even if it is obvious that the animal requires euthanasia it is important to ensure that it is not exposed to additional stressors such as large numbers of onlookers, people touching and talking to it, domestic animals, noise (helicopters and other vehicles) and extremes of temperature. The animal must be made as comfortable as possible. This may require moving it a short distance, providing shade or keeping it cool or moist.
If an animal is to be transported to a care facility or veterinary clinic, care must be taken to ensure that the method of transport is appropriate and as stress-free as possible. Most animals travel well in a dark, quiet, well-ventilated and cool environment. Cardboard boxes or bags (pillowcase, hessian sack) in an air-conditioned vehicle are adequate for most species. It is generally not recommended to offer the animal food or water, however this depends on the time between rescue and delivery to a care facility. The type of food and the method of administration should be appropriate to the species. The duration of the trip should be as short as possible. Animals should be checked frequently.
The ultimate aim of rescue and treatment of wildlife should be to rehabilitate and release the animal as quickly and effectively as possible. When first presented with a rescued wild animal, it is important to make an early assessment of its prognosis and suitability for rehabilitation and release. This is essential, to avoid unnecessary suffering and stress. It also avoids disappointment after substantial effort and emotional attachment to the animal. When large numbers of animals are involved in an incident such as an oil spill, bushfire or mass cetacean stranding, it is critical to triage animals. Triage ensures that maximum resources are put into animals that are most likely to survive. Human nature leads people to assist animals that are in the worst condition. The worst-affected animals—those with the least chance of survival—would thus take up time and resources that could be spent saving animals with a more realistic chance of survival. Effective triage avoids prolonged suffering in animals that clearly require immediate euthanasia.
Wild animals are very susceptible to stressors such as confinement, close proximity to other animals (particularly predators such as dogs and cats), noise and handling. If the prognosis is poor or the animal is unsuitable for release, a decision to euthanase must be made quickly. It is important that the decision to treat and rehabilitate an animal is not made to satisfy personal gratification, which may be to the detriment of the animal. If an animal is unsuitable for release but has legitimate educational or scientific value if kept in captivity, approval to do so can be sought from the relevant wildlife authority.
During initial treatment, careful consideration should be given to the judicious use of analgesics, sedatives or neuroleptic drugs to ensure that the animal is as comfortable and stress-free as possible. After initial treatment, most wild animals will require a period of rehabilitation prior to release to ensure they are restored to their former capacity. The treatment and rehabilitation period should be kept as short as possible and the environment in which the animal is held should be stress-free and provide for all its physical and psychological needs. Stress and stress-related illness are the most common causes of failure of treatment or death when treating and rehabilitating wild animals. Veterinarians are now fortunate that there is a network of experienced wildlife carers and rehabilitators who can assist with care and rehabilitation. This reservoir of knowledge and experience must not be ignored. It is important, however, that veterinarians have input into the rehabilitation process to ensure the ongoing health and welfare of the animal. This may be in the form of providing advice on nutrition and other preventative medicine or regular veterinary examinations.
Considerable time, effort and expense often goes into the treatment and rehabilitation of animals, but significantly less attention is often given to preparation for release, the release and post-release monitoring (Hall 2005). When making a pre-release assessment, veterinarians must keep in mind that the release of a native animal back into the wild must always be in the best interest of the animal. It must have recovered completely, both physically and behaviourally, to its former capacity to survive (Walraven 1994; Hall 2005). If an attempt has been made to treat animals by the application of prostheses these animals should not be released, as it is unlikely that any prosthesis will remain attached for the natural expected life of the animal. Some countries have laws and policies relating to the release of animals with disabilities, with strong recommendations not to do so (Hall 2005). Even though animals with disabilities are seen in the wild, apparently doing well, the long-term effect of the disability is difficult to assess. If an animal is released with a minor disability that appeared not to affect it during rehabilitation, it may be being committed to a life of long-term suffering and struggle for survival.
In many cases, the ultimate effect of release may be suffering and death. Many studies have demonstrated that mortality is high in animals released after rehabilitation (Brown & Tribe 2001). Despite this, it is considered by some that returning wildlife to the wild is more humane than a life in captivity. However, if not done properly animals may succumb to predation or disease or die from starvation or maladaption to an unfamiliar or inappropriate environment (IUCN 2000)—something that may not be justifiable. With our increasing knowledge and improved treatment, rehabilitation and release techniques, post-release survival has now improved and there is often minimal impact on animal welfare. In many cases this has been due to an assessment of treatment, rehabilitation and release techniques against information gained from long-term post-release monitoring studies.
Animals should always be released as close as possible to the rescue site. Many animals adapt to a particular environment, habitat or geographic area. Releasing them elsewhere may result in suffering due to maladaption. Similarly, the release of new individuals to a geographical area may pose genetic and disease risks to the resident population (Brown & Tribe 2001). The introduction of non-endemic disease or infection by the released animal may also result in considerable suffering.
2 ANIMAL HEALTH
The emergence of new infectious diseases in humans and other animals has been highlighted in recent years. Diseases such as severe acute respiratory syndrome (SARS), Australian bat lyssavirus, Hendra virus, Nipah virus, West Nile virus, monkeypox, avian influenza, rabbit haemorrhagic disease, pilchard herpesvirus, sarcoptic mange in various species, canine distemper in lions and seals, Tasmanian devil facial tumour disease and chytridiomycosis, to name a few, have had a devastating impact on animal and human populations. Wildlife populations play an important role in initiating and maintaining many of these diseases (Bunn & Woods 2005). A number of risk factors and processes have been identified, including geographic translocations of hosts and pathogens, new and or intensified contacts between hosts and pathogens, genetic change and environmental change (Daszak et al. 2005; Leighton 2005). The rescue, rehabilitation and release of wildlife, if not done properly, may contribute to these processes and lead to the disruption or disturbance of the natural balance between the host, environment and pathogens. When releasing rehabilitated wildlife, the health of the wild population and the ecosystem into which that animal is being released must take precedence over the welfare of the individual animal (IUCN 2000). Great care must be taken to maintain the balance of organisms naturally found within an animal and not introduce foreign organisms during the rehabilitation process. Each individual animal, rather than being a single organism, is a package of organisms (Woodford 2001). When releasing an animal we are releasing not only that individual but all the other organisms within it and on it.
Most wildlife rehabilitation and release and wildlife translocations are undertaken with complete lack of awareness or little regard for disease risks (Kirkwood & Sainsbury 1995; Griffith et al. 1993; Woodford 1993). Animals being rehabilitated may be exposed to new pathogens while in captivity and act as carriers when released, transmitting disease into a wild population with potentially devastating consequences for the population and the ecosystem in which it exists. Pathogens may be carried by released animals without causing disease in that species but causing severe disease in other species. Infectious disease may also be introduced to wild populations when animals with endemic disease are released into an area where those diseases do not occur. The released animal may also be exposed to diseases to which it has not developed immunity (IUCN 2000). These immunologically naive animals may become infected and die, or become carriers shedding large numbers of organisms and infecting endemic animals (Kirkwood & Sainsbury 1995; Griffith et al. 1993; Viggers et al. 1993; Woodford 1993). The release of an animal back into the wild is a stressful time for that animal and others in the area, due to competition. When animals are stressed disease can have a significant impact.
It does seem surprising that the incidence of disease introduction through the release of rehabilitated or translocated wildlife or the disease-related failure of wildlife releases or translocations is not higher, considering the large number of releases or translocations. However, it is highly likely that these scenarios go undetected or are underestimated given the general lack of post-release monitoring or surveillance of wild populations into which animals are released (Griffith et al. 1993), and the absence of veterinary involvement in some of these programs. The disease risks associated with wildlife translocation are frequently overlooked by many wildlife agencies responsible for these programs.
2.1 Disease risk assessment
Adequate disease risk assessment when dealing with wildlife presents considerable difficulty for two reasons. Firstly, there are few reliable tests for the detection of many wildlife pathogens. Secondly, many species of wild animals carry infectious agents of which we have little or no knowledge (Kirkwood & Sainsbury 1995). Although there have been surveys of the health of wild populations of some species, for the majority of species we have little knowledge of the organisms and pathogens they may naturally harbour. For these reasons appropriate measures must be taken to reduce the risk of disease during the rehabilitation and release of wildlife, including initial and ongoing clinical assessment, laboratory tests (haematology, biochemistry, serology, faecal examination, microbiology), screening tests for specific diseases (e.g. tuberculin testing), prophylactic procedures and treatments, quarantine, enclosure design and husbandry (Viggers et al. 1993; Kirkwood & Sainsbury 1995; IUCN 1998). An understanding of disease processes and the measures required in preventing disease transmission and spread is essential for all veterinarians and others involved in the rehabilitation and release of wildlife.
It is important to determine if the reason for presentation of a rescued animal is an infectious disease. Wildlife may require rescuing as a result of a natural event (disease, old age, predation, weather conditions, natural disasters such as fires or floods) or some form of human activity (hit by car, dog or cat attack, oil spills, poisoning, contamination, collision with man-made objects, trapping, shooting). The latter are far more common, but an animal that has succumbed to trauma or predation may have been weakened by a pre-existing disease process. In general terms, animals suffering from an infectious disease rather than a traumatic injury alone are poorer candidates for release and possibly pose a greater risk to other patients in the rehabilitation facility and to the population if released. It is important to screen all incoming rehabilitation patients for the presence of clinical or subclinical infectious disease (see 2.1.1).
Ideally, the initial clinical assessment of all rehabilitation patients should be carried out by a wildlife veterinarian. In each case, however, a disease risk (and cost–risk) assessment can be made by the wildlife rehabilitator. In some cases it may be clear that there is no underlying disease process (e.g. orphaned marsupial pouch young) and a clinical assessment by a veterinarian may not be necessary. If a clinical assessment is made it should include a physical examination, haematology and serum biochemistry analysis, serology, faecal examination for bacteria and parasites, evaluation of the blood smear for parasites and other sampling or testing as appropriate to the species (e.g. chlamydophila in koalas and birds, cryptococcus in koalas, circovirus in psittacine birds, tuberculosis in pinnipeds). In some cases it may be appropriate to collect serum or plasma to be stored at 270°C for retrospective disease investigation.
Wildlife may also be infected with exotic or notifiable diseases (e.g. avian influenza, Newcastle’s disease, West Nile virus, Pacheco’s disease, monkeypox). It is quite possible that an animal rescued by a wildlife carer may be the first case of one of these diseases in a country. Monitoring wildlife health may facilitate early detection of threats to biosecurity and rescued wildlife should be included as part of wildlife health surveillance systems. Monitoring the emergence of wildlife diseases is an important contribution that wildlife veterinarians and wildlife carers can make (Clark 2002