Topics in Compan An Med 28 (2013) 131–134
Topical Review
The Crucial Contribution of Veterinarians to Conservation Biology Richard P. Reading, PhDa,n, David E. Kenny, VMDa, Kevin T. Fitzgerald, DVM, PhD, DABVPb Keywords: animal capture conservation disease immobilization veterinarian wildlife health a
Department of Conservation Biology, Denver Zoological Foundation, Denver, CO, USA
b
Alameda East Veterinary Hospital, Denver, CO, USA
n
Address reprint requests to Richard P. Reading, PhD, Department of Conservation Biology, Denver Zoological Foundation, 2300 Steele St, Denver, CO 80205, USA E-mail: [email protected] (R.P. Reading)
Conservation biology is a relatively new (began in the 1980s), value-based discipline predicated on the belief that biological diversity—from genes to populations to species to communities to ecosystems—is good and extinction is bad. Conservation biology grew from the recognition that the Earth has entered its sixth great extinction event, one that differs from previous great extinctions in that a single species— Homo sapiens—has caused this biodiversity crisis. A diverse, interacting set of variables drive current extinctions. As such, to succeed, conservation efforts usually require broad-based, interdisciplinary approaches. Conservationists increasingly recognize the importance of contributions by veterinary science, among many other disciplines, to collaborative efforts aimed at stemming the loss of biodiversity. We argue that, to improve success rates, many wildlife conservation programs must incorporate veterinarians as part of an interdisciplinary team to assess and address problems. Ideally, veterinarians who participate in conservation would receive specialized training and be willing to work as partners as part of a larger team of experts who effectively integrate their work rather than work independently (i.e., work as interdisciplinary, as opposed to multidisciplinary, teams, respectively). In our opinion, the most successful and productive projects involve interdisciplinary teams involving both biological and nonbiological specialists. Some researchers hold multiple degrees in biology and veterinary medicine or the biological and social sciences. These experts can often offer unique insight. We see at least 3 major areas in which veterinarians can immediately offer great assistance to conservation efforts: (1) participation in wildlife capture and immobilization, (2) leadership or assistance in addressing wildlife health issues, and (3) leadership or assistance in addressing wildlife disease issues, including using wildlife as sentinels to identify new and emerging diseases or epidemics of old diseases. We cover each of these main topics in detail. & 2013 Elsevier Inc. All rights reserved.
Wildlife Capture and Immobilization A large number of wildlife conservation programs rely on data gathered from animals in the field. Often, collecting those data requires animal capture and, in some cases, chemical immobilization. Veterinary assistance is key in either case. At a minimum, veterinarians should assist in project design, review, and input for an Animal Welfare Committee when projects use chemical immobilization. We strongly urge using veterinarians to monitor captured animals whether drugged or not. Conservationists capture animals for a wide variety of reasons, but most commonly (1) to apply individual identifiers, such as leg bands, ear tags, wing tags, and passive integrated transponders tags, to track individuals and monitor their behaviors and fates; (2) to attach telemetry equipment to monitor movements and survivorship, such as radio, satellite, or global positioning system collars (or some combination of these); (3) to attach remote data loggers that monitor an animal's vital signs, environment, or behavior; or (4) for a variety of other reasons, such as collecting biological samples to monitor for toxins or disease. Every animal capture, whether it uses chemical or manual restraint, imposes stress on the captured animal and has the potential for injury. As early as 1968, pioneer wildlife capture expert Harthoorn1 expressed the benefits of having the “skill and training” in anesthesiology and pharmacology to restrain a wild animal with minimal morbidity and mortality. In the intervening 45 years, the number of pharmaceuticals and cocktails of 2-3 drugs available for immobilizations has increased dramatically.2 We now have specific protocols for individual species, often with 2-3 alternative protocols, depending upon drug availability. This dramatic increase in knowledge requires wildlife professionals to keep current with the veterinary literature, capture courses, and
attendance at continuing education conferences. Several relatively recent and excellent veterinary texts focus solely on the topic of wildlife capture and chemical restraint.3-6 Especially in programs focused on endangered or threatened species, an increasingly educated public demands the presence of appropriate levels of expertise at captures. The public may not accept the excuse that including a veterinarian on the team is too costly. Following physical capture or chemical restraint, veterinarians can monitor animals to provide an early warning of a deteriorating situation and prematurely conclude the capture. We use veterinarians in all of our projects throughout the world that involve captures of animals as diverse as snakes, hedgehogs, raptors, and large mammals. For example, in Mongolia, we use drive nets and physical restraint to capture and collar argali sheep (Ovis ammon) and Siberian ibex (Capra sibirica).7 Veterinarians monitor the vital signs of captured individuals and have the ultimate authority to intervene and even release animals whose survival we might compromise by continued restraint, even if we have not yet completed processing or collaring the animal. The veterinarian monitors vital rates (temperature, pulse, and respiration) and works to mitigate stress and overheating before calling for an early release. Such efforts likely help reduce capture-related morbidity and mortality. Better understanding capture myopathy, a big concern for capture by drive-netting, represents a ripe field of research for field veterinarians. Animals injured during capture undoubtedly benefit from the presence of veterinarians who can provide some relief from minor wounds, such as by antibiotics or temporary wraps. In some cases, the team can maintain more severely injured individuals in captivity to permit healing before release or for incorporation into captive breeding programs. Such approaches become more
1527-3369/$ - see front matter & 2013 Topics in Companion Animal Medicine. Published by Elsevier Inc. http://dx.doi.org/10.1053/j.tcam.2013.09.003
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important for critically endangered species represented by only dozens of individuals. For example, after some people entered the nest of a Eurasian Black Vulture (Aegypius monachus) (Figure 1) and caused the chick to break its wing, we used a veterinarian to assess and treat the break. Unfortunately, the bird would never fly, so we brought the animal into captivity at Denver Zoo to join a population that desperately needed additional founder animals. The importance of veterinarians has increased significantly for capture operations that use chemical restraint. The pharmacology for animal restraint has developed rapidly over the past several decades with the introduction of new drugs and new cocktails of drugs for use with specific species or groups of species. We strongly recommend relying on trained veterinarians for any animal capture that requires the use of anesthesia. Although many field biologists routinely use drugs to immobilize animals in the field, veterinarians receive better training in addressing complications and emergencies that may arise during immobilization or anesthesia. They also arguably receive better training in working with and handling dangerous drugs, like narcotics. Local or federal legislation may require participation by a licensed veterinarian when dealing with controlled substances. Most protocols now involve the use of controlled substances (narcotics and dissociatives). Some species require surgery to implant telemetry devices within animal bodies. We strongly urge using trained veterinary surgeons to perform these procedures given the risk of infection and other complications. One of us (D.K.) implanted transmitters in the body cavities of American badgers (Taxidea taxus) as part of a project in Colorado, US. In some cases, this might require a specialist. For example, one of us (K.F.) implanted tiny telemetry transmitters in the bodies of snakes in the United States and Mongolia.8 Although most veterinarians involved in conservation projects likely deliver drugs to target animals themselves, we recognize that in many cases biologists may also possess expertise in drug delivery through dart guns, blow guns, pole darts, etc. Using a team approach, the veterinarian can develop the drug protocol and the marksman can deliver the drug. We recommend using the individual with the best skill, such as marksmanship, while noting the very different skill set involved with shooting darts as opposed to bullets. Nevertheless, we believe a veterinarian should always prepare or help prepare darts and be present during immobilization. As with physical restraint, veterinarians generally are better trained to monitor drugged animals and to address any problems that may develop. By definition, conservation projects usually
Fig. 1. Dr. Rich Reading with a young Eurasian Black Vulture (Aegypius monachus) in Mongolia.
work with small populations of threatened and endangered species for which the death of any individual could pose a significant loss to the population.
Wildlife Health Conservation biologists increasingly recognize the importance of addressing issues of wildlife health in conservation programs. The major factors implicated in the current biodiversity crisis include (1) habitat alteration, elimination, and degradation; (2) overharvest and use of species; (3) competition, predation, and disease from species introduced outside their native ranges by people; and (4) secondary extinctions resulting from the loss of dependent species.9-11 In addition to the direct affects of disease, the stress induced by of these 4 so-called “deadly horsemen of the biodiversity apocalypse” can cause additional health problems in wildlife populations.4 In this section, we consider wildlife diseases and epizootics, internal and external parasites, and the influence of stress on body condition in wild animal populations.
Wildlife Diseases and Epizootics Diseases pose some of the greatest threats to remaining wildlife populations. These include locally endemic diseases that have increased in virulence or frequency in recent decades; introduced diseases for which local organisms often demonstrate little or no resistance; and emerging diseases that often arise suddenly by quickly transferring, mutating, or “jumping” from one host to another. Diseases often persist in environments and periodically irrupt into epizootics when conditions favor them, such as when a large proportion of individuals in a population become stressed owing to external factors like human encroachment or environmental degradation (described later). In addition, as livestock populations increase and intrude further into areas once dominated by wildlife, the potential for disease transfer from domestic to wild animals increases, often with severe repercussions for wildlife. More devastating than native diseases, people have moved disease organisms all over the Earth with intentional (e.g., livestock) and unintentional (e.g., rats on ships) introductions of exotic species. For example, black-footed ferrets (Mustela nigripes) have faced double jeopardy by plague (that came with unintentionally introduced rats) that kills them and their prairie dog (Cynomys spp.) prey and distemper (that came with intentionally introduced domestic dogs).12,13 Ferrets demonstrate such hypersensitivity to distemper that animals die from shock when injected with a pasteurized (e.g., killed) virus as a vaccine.14 Similarly, mortality rates from plague for prairie dogs infected with the Yersinia pestis bacterium often exceed 99%.15,16 Other examples of devastating diseases include Chytridiomycosis in amphibians,17,18 the Varroa destructor mite that spreads the deadly deformed wing virus in honeybees (Apis spp.),19 and white-nose syndrome caused by the fungus Geomyces destructans in bats.20,21 Species and even populations faced with novel diseases can eventually develop resistance to disease-causing microorganisms that often evolved to infect closely related species living in other parts of the world if the population is not too severely reduced, but in some cases the presence of alternative, more resistant hosts can force a species to extinction before it can develop sufficient resistance to persist. Practices such as baiting deer for hunting can result in unintended consequences by concentrating and holding animals in higher than normal numbers. These abnormally high densities can result in transmission of tuberculosis or chronic wasting disease
R.P. Reading et al. / Topics in Companion An Med 28 (2013) 131–134
and possibly interfere with normal migratory movements.20 Veterinarians receive much of the prerequisite training and education to assist in researching and monitoring the role of diseases in the health of ecosystems and wildlife populations. For an excellent current review of the many known and emerging diseases refer to the Wildlife Professional Spring 2012; 6(1). The agricultural community often indicts wildlife as reservoirs for disease transferred to domestic animals, so we need good science before implementing potentially devastating management decisions that could affect the persistence of wildlife. Local human populations also express serious concerns over diseases that have zoonotic (transmission from animals to humans) implications. Parasites Wildlife species harbor a diverse community of internal and external parasites. Most of these parasites, such as skin mites, exert negligible negative effects on their hosts, so long as they remain healthy with an intact and functioning immune system. Indeed, veterinarians often use heavy parasite loads as a symptom, rather than a cause, of poor health and possibly a degraded habitat. However, parasites can carry diseases, such as Rocky Mountain spotted fever (caused by the bacterium Rickettsia rickettsii) carried by ticks, or cause severe medical problems themselves. Heavy parasitism can contribute to mortality or reduced fecundity in already compromised individuals. Those with agricultural interests often blame wildlife for functioning as reservoirs for parasites that afflict domestic livestock. For example, llama (Lama glama) herders in the Andes blame vicuna (Vicugna vicugna) for acting as reservoirs for enteric parasites. In truth, overuse of antihelmintic drugs has created resistance to these drugs, similar to the resistance we now recognize that has followed the overuse of antibiotics. Killing vicunas will not solve the problem. Veterinarians must become a part of a solution that helps herders develop more sustainable parasite control programs, such as the creation of parasite refuges.21 Veterinarians routinely treat domesticated animals for a wide variety of internal parasites, but especially those that infect the digestive tracts of animals. Under most field conditions, conservation veterinarians would not treat free-ranging animals for parasites. Evaluating free-ranging species for internal parasites can provide early notice of a deteriorating ecosystem. Increased parasite loads often indicate stressed and poorly nourished animals, and heavy parasite loads can compromise immune systems. Because livestock growers often blame wildlife for infecting their herds with parasites, research should establish the parasite species that wildlife harbors and the ones that likely emanate from the livestock herds themselves. External parasites infect the skin, hair, scales, and feathers of animals. Many, such as ticks and leeches, strive to ingest the blood of the host animal. Others feed on the skin or flesh or animal, such as scabies, mange, and fly larvae. In Mongolia, we noted a possible linkage between unusually wet weather and the appearance of feather lice on Eurasian Black Vulture (Aegypius monachus) chicks. We have not examined whether these lice affect chick survivorship, but we plan to closely monitor this situation in the future. Many ectoparasites also act as vectors for zoonotic diseases, such as ticks that carry Lyme disease (caused by Borrelia spp. bacteria). Knowing which free-ranging species can act as a host for an arthropod vector can have important consequences for both domesticated animals and human health. In recent times, veterinarians have begun debating the efficacy and desirability of prophylactically treating seemingly healthy wild (and even domestic) animals for parasites.22 Wide use of such medicines may result in the evolution of parasites that are resistant to medicines, thus compromising our ability to treat
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animals that require help in battling dangerously high parasite loads. Medicines used to kill parasites can also produce deleterious secondary effects in the environment. For example, antihelmintic drugs provided to horses kill dung beetles that play a crucial role in recycling manure.22
Stress, Body Condition, and General Health Field veterinarians can help monitor the stress, health, and body condition of individuals in wild populations and collect valuable biological samples for further study. Monitoring the health status of individuals helps conservation programs assess a wide variety of factors, such as the effects of new research methodologies or conservation initiatives. For example, does a type of telemetry unit negatively affect individuals that wear it? As a specific example, we used veterinarians to assess the possible effects of a new telemetry backpack design we developed for vultures using captive birds. Do attempts to field vaccinate susceptible individuals cause more harm than good? Dr Rosie Woodroffe has studied the efficacy and possible side effects of a remotely delivered rabies vaccine for African wild dogs (Lycaon pictus).23-25 Rabies outbreaks have caused local extirpations of wild dog populations in the past, so field vaccinations promise to dramatically help African wild dog conservation, but we must ensure that such approaches do not inadvertently harm wild dogs in other ways. Equally important, animals brought into captivity to assist in establishing or maintaining “safety” populations of endangered species must undergo careful screening and quarantine to reduce the chances of introducing diseases and parasites into the captive population. Similarly, animal destined for reintroduction programs should undergo similar procedures to avoid transferring diseases or parasites from the source population (captive or wild) to the destination population.26 Increased stress can decrease survivorship and reproduction in animals. Stress also increases susceptibility to disease and parasitism. Research now focuses on assessing the levels of stress that individuals face and the methods of mitigating that stress. Increasingly, we have discovered that wildlife suffer from diverse problems owing to pollutants that humans release into the environment. Poisoning from DDT used to control insect populations thins raptor eggshells, reducing viability27 and lead from spent ammunition contaminates scavengers that eat shot carcasses and waterfowl that pick up spent lead pellets at the bottom of water bodies.28,31,32 Banning DDT has largely resolved that problem,27 but lead poisoning continues to frustrate efforts for conservation of California condor (Gymnogyps californianus) and other vulture species.29 Veterinary products used to treat domestic animals can sometimes produce harmful or deadly affects on wildlife, such as the massive vulture die-offs due to the use of diclofenac to treat livestock30,33 and dung beetle mortality from anthelmintic drugs used on livestock.22 Thus, we argue for the importance of conducting health screening on wild animals, including evaluating blood chemistries and titer for known problematic diseases when possible. Often, wild species can serve as sentinels to warn us of new disease and toxins in the environment.
Conclusions Increasing recognition of the importance of addressing animal disease and health issues in conservation programs has led to greater involvement by veterinarians. Indeed, we argue that interdisciplinary teams that include veterinary professions
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promise to greatly improve conservation success rates. Veterinarians can assist conservation projects in a variety of ways, but primarily to assist with animal capture and immobilization, assess wildlife health, and help mitigate the effects of wildlife diseases. Already field veterinarians play an important role in each of these areas, but as the number of endangered species continues to grow and as humans more commonly spread diseases and pathogens around the world, the contribution of veterinarians becomes ever more important.
Acknowledgments The Denver Zoological Foundation and Alameda East Veterinary Hospital supported our work. We thank the many people who assisted with various aspect of our thinking and work that contributed to this article including Sukh Amgalanbaatar, Cindy Bickel, Dr Diana Boon, Dr Tony DeNicola, Dr Glyn Maude, V. Veer, Ganchimeg Wingard, Earthwatch volunteers, and our many graduate students. References 1. Harthoorn AM. Problems and hazards of chemical restraint in wild animals. Inter Zoo Yearbook 8:215–220, 1968 2. Kock MD, Lance WR, Jessup DA. The art of chemical capture. Wild Prof 6:34–39, 2012 3. Kreeger TJ, Arnemo JM: Handbook of Wildlife Chemical Immobilization. 4th ed. Greyton, South Africa: International Wildlife Veterinary Services; 2007 4. Kock MD, Meltzer D, Burroughs R. Chemical and Physical Restraint of Wild Animals. Greyton, South Africa: International Wildlife Veterinary Services; 2006 5. Fowler Jr. FJ. Survey research methods (applied social research methods series no.1). 4th ed. Thousand Oaks, CA: Sage Publications, Inc; 2008 6. Nielsen L. Chemical Immobilization of Wild and Exotic Animals. Ames, Iowa: Iowa State University Press; 1999 7. Kenny D, DeNicola A, Amgalanbaatar S, et al. Successful field capture techniques for free-ranging argali sheep (Ovis ammon) in Mongolia. Zoo Bio 27:137–144, 2008 8. Fitzgerald KT, Vera R. Biotelemetry in reptiles. In: Mader D, editor. Reptile Medicine and Surgery. 2nd ed. St. Louis: Elsevier; 2006. p. 613–617 9. Diamond J. “Normal” extinctions of isolated populations. In: Nitecki M, editor. Nature. Chicago: University of Chicago Press; 1984. p. 191–246 10. Diamond J. Overview of recent extinctions. In: Western D, Pearl M, editors. Conservation for the Twenty-first Century. New York: Oxford University Press; 1989. p. 37–41 11. Wilson EO. The Diversity of Life. Cambridge, MA: Belknap Press; 1992 12. Matchett MR, Biggins DE, Carlson V, Powell B, Rocke T. Enzootic plague reduces black-footed ferret (Mustela nigripes) survival in Montana. Vector Borne Zoonotic Dis 10:27–35, 2010
13. Miller B, Reading RP, Forrest S. Prairie Night: Black-Footed Ferrets and the Recovery of Endangered Species. Washington, DC: Smithsonian Press; 1996 14. Williams ES, Anderson SL, Cavender J, et al. Vaccination of black-footed ferret (Mustela nigripes) X Siberian polecat (M. eversmanni) hybrids and domestic ferrets (M. putorius furo) against canine distemper. J Wildlife Dis 32:417–423, 1996 15. Johnson TL, Cully Jr JF, Collinge SK, Ray C, Frey CM, Sandercock BK. Spread of plague among black-tailed prairie dogs is associated with colony spatial characteristics. J Wildlife Manage 75:357–368, 2011 16. Rocke TE, Williamson J, Cobble KR. Resistence to plague among black-tailed prairie dog populations. Vector Borne Zoonotic Dis 12:111–116, 2012 17. Voyles J, Young S, Berger L, et al. Pathogenesis of chytridiomycosis, a cause of catastrophic amphibian declines. Science 326:582–585, 2009 18. Fisher MC, Garner TWJ, Walker SF. Global emergence of Batrachochytrium dendrobatidis and amphibian chytridiomycosis in space, time, and host. Ann Rev Microbiol 63:291–310, 2009 19. Martin SJ, Highfield AC, Brettell L, et al. Global honey bee viral landscape altered by a parasitic mite. Science 336:1304–1306, 2012 20. Blehert DS, Hicks AC, Behr M, et al. Bat white-nose syndrome: an emerging fungal pathogen? Science 323:227, 2009 21. Lorch JM, Meteyer CU, Behr MJ, et al. Experimental infection of bats with Geomyces destructans causes white-nose syndrome. Nature 480:376–378, 2011 22. Anonymous. Deer Baiting Issues in Michigan. Michigan Department of Natural Resources. Wildlife Division Issue Review Paper 5, Michigan Project W-127-R; 1999. 23. Fowler M. Restraint and Handling of Wild and Domestic Animals. 3rd ed. Ames, IA: Blackwell Publishing; 2008 24. Pech CL, Doole GJ, Pluske JM. The value of refugia in managing anthelmintic resistance: a modeling approach. Proc Aust Agriculture Resour Econ Soc:1–35, 2009 25. Harmon J. The worm turns. Integrative Vet Care V212:30–33, 2012 26. Prager KC, Woodroffe R, Cameron A, Haydon DT. Vaccination strategies to conserve the endangered African wild dogs (Lycaon pictus). Biol Conserv 144:1940–1948, 2011 27. Woodroff R, Donnelly CA. Risk of contact between endangered African wild dogs Lycaon pictus and domestic dogs: opportunities for pathogen transmission. J Appl Ecol 48:1345–1354, 2011 28. Woodroff R, Prager KC, Mumson L, Conrad PA, Dubovi EJ, Mazet JAK. Contact with domestic dogs increases pathogen exposure in endangered African wild dogs (Lycaon pictus). PLoS ONE 7:e30099, http://dx.doi.org/10.1371/journal. pone.0030099 29. IUCN RSG. IUCN guidelines for reintroductions and other conservation translocations. Gland, Switzerland: IUCN Species Survival Commission Reintroduction Specialist Group; 2012 30. Clark KE, Zhao Y, Kane CM. Organochlorine pesticides, PCBs, dioxins, and metals in postterm peregrine falcon (Falco peregrinus) eggs from the MidAtlantic States, 1993-1999. Arch Environ Contam Tox 57:174–184, 2009 31. Kelly TR, Johnson CK. Lead exposure in free-flying turkey vultures is associated with big game hunting in California. PLOS One 6:e15350, http://dx.doi.org/ 10.1371/journal.pone.0015350 32. Finkelstein ME, Doak DF, Goerge D, et al. Lead poisoning and the deceptive recovery of the critically endangered California condor. Proc Natl Acad Sci U S A 109:11449–11454, 2012 33. Chaudhary A, Subedi TR, Giri JB, et al. Population trends of critically endangered Gyps vultures in the lowlands of Nepal. Bird Conserv Internat 22:270–278, 2012
Topical Review
The Crucial Contribution of Veterinarians to Conservation Biology Richard P. Reading, PhDa,n, David E. Kenny, VMDa, Kevin T. Fitzgerald, DVM, PhD, DABVPb Keywords: animal capture conservation disease immobilization veterinarian wildlife health a
Department of Conservation Biology, Denver Zoological Foundation, Denver, CO, USA
b
Alameda East Veterinary Hospital, Denver, CO, USA
n
Address reprint requests to Richard P. Reading, PhD, Department of Conservation Biology, Denver Zoological Foundation, 2300 Steele St, Denver, CO 80205, USA E-mail: [email protected] (R.P. Reading)
Conservation biology is a relatively new (began in the 1980s), value-based discipline predicated on the belief that biological diversity—from genes to populations to species to communities to ecosystems—is good and extinction is bad. Conservation biology grew from the recognition that the Earth has entered its sixth great extinction event, one that differs from previous great extinctions in that a single species— Homo sapiens—has caused this biodiversity crisis. A diverse, interacting set of variables drive current extinctions. As such, to succeed, conservation efforts usually require broad-based, interdisciplinary approaches. Conservationists increasingly recognize the importance of contributions by veterinary science, among many other disciplines, to collaborative efforts aimed at stemming the loss of biodiversity. We argue that, to improve success rates, many wildlife conservation programs must incorporate veterinarians as part of an interdisciplinary team to assess and address problems. Ideally, veterinarians who participate in conservation would receive specialized training and be willing to work as partners as part of a larger team of experts who effectively integrate their work rather than work independently (i.e., work as interdisciplinary, as opposed to multidisciplinary, teams, respectively). In our opinion, the most successful and productive projects involve interdisciplinary teams involving both biological and nonbiological specialists. Some researchers hold multiple degrees in biology and veterinary medicine or the biological and social sciences. These experts can often offer unique insight. We see at least 3 major areas in which veterinarians can immediately offer great assistance to conservation efforts: (1) participation in wildlife capture and immobilization, (2) leadership or assistance in addressing wildlife health issues, and (3) leadership or assistance in addressing wildlife disease issues, including using wildlife as sentinels to identify new and emerging diseases or epidemics of old diseases. We cover each of these main topics in detail. & 2013 Elsevier Inc. All rights reserved.
Wildlife Capture and Immobilization A large number of wildlife conservation programs rely on data gathered from animals in the field. Often, collecting those data requires animal capture and, in some cases, chemical immobilization. Veterinary assistance is key in either case. At a minimum, veterinarians should assist in project design, review, and input for an Animal Welfare Committee when projects use chemical immobilization. We strongly urge using veterinarians to monitor captured animals whether drugged or not. Conservationists capture animals for a wide variety of reasons, but most commonly (1) to apply individual identifiers, such as leg bands, ear tags, wing tags, and passive integrated transponders tags, to track individuals and monitor their behaviors and fates; (2) to attach telemetry equipment to monitor movements and survivorship, such as radio, satellite, or global positioning system collars (or some combination of these); (3) to attach remote data loggers that monitor an animal's vital signs, environment, or behavior; or (4) for a variety of other reasons, such as collecting biological samples to monitor for toxins or disease. Every animal capture, whether it uses chemical or manual restraint, imposes stress on the captured animal and has the potential for injury. As early as 1968, pioneer wildlife capture expert Harthoorn1 expressed the benefits of having the “skill and training” in anesthesiology and pharmacology to restrain a wild animal with minimal morbidity and mortality. In the intervening 45 years, the number of pharmaceuticals and cocktails of 2-3 drugs available for immobilizations has increased dramatically.2 We now have specific protocols for individual species, often with 2-3 alternative protocols, depending upon drug availability. This dramatic increase in knowledge requires wildlife professionals to keep current with the veterinary literature, capture courses, and
attendance at continuing education conferences. Several relatively recent and excellent veterinary texts focus solely on the topic of wildlife capture and chemical restraint.3-6 Especially in programs focused on endangered or threatened species, an increasingly educated public demands the presence of appropriate levels of expertise at captures. The public may not accept the excuse that including a veterinarian on the team is too costly. Following physical capture or chemical restraint, veterinarians can monitor animals to provide an early warning of a deteriorating situation and prematurely conclude the capture. We use veterinarians in all of our projects throughout the world that involve captures of animals as diverse as snakes, hedgehogs, raptors, and large mammals. For example, in Mongolia, we use drive nets and physical restraint to capture and collar argali sheep (Ovis ammon) and Siberian ibex (Capra sibirica).7 Veterinarians monitor the vital signs of captured individuals and have the ultimate authority to intervene and even release animals whose survival we might compromise by continued restraint, even if we have not yet completed processing or collaring the animal. The veterinarian monitors vital rates (temperature, pulse, and respiration) and works to mitigate stress and overheating before calling for an early release. Such efforts likely help reduce capture-related morbidity and mortality. Better understanding capture myopathy, a big concern for capture by drive-netting, represents a ripe field of research for field veterinarians. Animals injured during capture undoubtedly benefit from the presence of veterinarians who can provide some relief from minor wounds, such as by antibiotics or temporary wraps. In some cases, the team can maintain more severely injured individuals in captivity to permit healing before release or for incorporation into captive breeding programs. Such approaches become more
1527-3369/$ - see front matter & 2013 Topics in Companion Animal Medicine. Published by Elsevier Inc. http://dx.doi.org/10.1053/j.tcam.2013.09.003
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important for critically endangered species represented by only dozens of individuals. For example, after some people entered the nest of a Eurasian Black Vulture (Aegypius monachus) (Figure 1) and caused the chick to break its wing, we used a veterinarian to assess and treat the break. Unfortunately, the bird would never fly, so we brought the animal into captivity at Denver Zoo to join a population that desperately needed additional founder animals. The importance of veterinarians has increased significantly for capture operations that use chemical restraint. The pharmacology for animal restraint has developed rapidly over the past several decades with the introduction of new drugs and new cocktails of drugs for use with specific species or groups of species. We strongly recommend relying on trained veterinarians for any animal capture that requires the use of anesthesia. Although many field biologists routinely use drugs to immobilize animals in the field, veterinarians receive better training in addressing complications and emergencies that may arise during immobilization or anesthesia. They also arguably receive better training in working with and handling dangerous drugs, like narcotics. Local or federal legislation may require participation by a licensed veterinarian when dealing with controlled substances. Most protocols now involve the use of controlled substances (narcotics and dissociatives). Some species require surgery to implant telemetry devices within animal bodies. We strongly urge using trained veterinary surgeons to perform these procedures given the risk of infection and other complications. One of us (D.K.) implanted transmitters in the body cavities of American badgers (Taxidea taxus) as part of a project in Colorado, US. In some cases, this might require a specialist. For example, one of us (K.F.) implanted tiny telemetry transmitters in the bodies of snakes in the United States and Mongolia.8 Although most veterinarians involved in conservation projects likely deliver drugs to target animals themselves, we recognize that in many cases biologists may also possess expertise in drug delivery through dart guns, blow guns, pole darts, etc. Using a team approach, the veterinarian can develop the drug protocol and the marksman can deliver the drug. We recommend using the individual with the best skill, such as marksmanship, while noting the very different skill set involved with shooting darts as opposed to bullets. Nevertheless, we believe a veterinarian should always prepare or help prepare darts and be present during immobilization. As with physical restraint, veterinarians generally are better trained to monitor drugged animals and to address any problems that may develop. By definition, conservation projects usually
Fig. 1. Dr. Rich Reading with a young Eurasian Black Vulture (Aegypius monachus) in Mongolia.
work with small populations of threatened and endangered species for which the death of any individual could pose a significant loss to the population.
Wildlife Health Conservation biologists increasingly recognize the importance of addressing issues of wildlife health in conservation programs. The major factors implicated in the current biodiversity crisis include (1) habitat alteration, elimination, and degradation; (2) overharvest and use of species; (3) competition, predation, and disease from species introduced outside their native ranges by people; and (4) secondary extinctions resulting from the loss of dependent species.9-11 In addition to the direct affects of disease, the stress induced by of these 4 so-called “deadly horsemen of the biodiversity apocalypse” can cause additional health problems in wildlife populations.4 In this section, we consider wildlife diseases and epizootics, internal and external parasites, and the influence of stress on body condition in wild animal populations.
Wildlife Diseases and Epizootics Diseases pose some of the greatest threats to remaining wildlife populations. These include locally endemic diseases that have increased in virulence or frequency in recent decades; introduced diseases for which local organisms often demonstrate little or no resistance; and emerging diseases that often arise suddenly by quickly transferring, mutating, or “jumping” from one host to another. Diseases often persist in environments and periodically irrupt into epizootics when conditions favor them, such as when a large proportion of individuals in a population become stressed owing to external factors like human encroachment or environmental degradation (described later). In addition, as livestock populations increase and intrude further into areas once dominated by wildlife, the potential for disease transfer from domestic to wild animals increases, often with severe repercussions for wildlife. More devastating than native diseases, people have moved disease organisms all over the Earth with intentional (e.g., livestock) and unintentional (e.g., rats on ships) introductions of exotic species. For example, black-footed ferrets (Mustela nigripes) have faced double jeopardy by plague (that came with unintentionally introduced rats) that kills them and their prairie dog (Cynomys spp.) prey and distemper (that came with intentionally introduced domestic dogs).12,13 Ferrets demonstrate such hypersensitivity to distemper that animals die from shock when injected with a pasteurized (e.g., killed) virus as a vaccine.14 Similarly, mortality rates from plague for prairie dogs infected with the Yersinia pestis bacterium often exceed 99%.15,16 Other examples of devastating diseases include Chytridiomycosis in amphibians,17,18 the Varroa destructor mite that spreads the deadly deformed wing virus in honeybees (Apis spp.),19 and white-nose syndrome caused by the fungus Geomyces destructans in bats.20,21 Species and even populations faced with novel diseases can eventually develop resistance to disease-causing microorganisms that often evolved to infect closely related species living in other parts of the world if the population is not too severely reduced, but in some cases the presence of alternative, more resistant hosts can force a species to extinction before it can develop sufficient resistance to persist. Practices such as baiting deer for hunting can result in unintended consequences by concentrating and holding animals in higher than normal numbers. These abnormally high densities can result in transmission of tuberculosis or chronic wasting disease
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and possibly interfere with normal migratory movements.20 Veterinarians receive much of the prerequisite training and education to assist in researching and monitoring the role of diseases in the health of ecosystems and wildlife populations. For an excellent current review of the many known and emerging diseases refer to the Wildlife Professional Spring 2012; 6(1). The agricultural community often indicts wildlife as reservoirs for disease transferred to domestic animals, so we need good science before implementing potentially devastating management decisions that could affect the persistence of wildlife. Local human populations also express serious concerns over diseases that have zoonotic (transmission from animals to humans) implications. Parasites Wildlife species harbor a diverse community of internal and external parasites. Most of these parasites, such as skin mites, exert negligible negative effects on their hosts, so long as they remain healthy with an intact and functioning immune system. Indeed, veterinarians often use heavy parasite loads as a symptom, rather than a cause, of poor health and possibly a degraded habitat. However, parasites can carry diseases, such as Rocky Mountain spotted fever (caused by the bacterium Rickettsia rickettsii) carried by ticks, or cause severe medical problems themselves. Heavy parasitism can contribute to mortality or reduced fecundity in already compromised individuals. Those with agricultural interests often blame wildlife for functioning as reservoirs for parasites that afflict domestic livestock. For example, llama (Lama glama) herders in the Andes blame vicuna (Vicugna vicugna) for acting as reservoirs for enteric parasites. In truth, overuse of antihelmintic drugs has created resistance to these drugs, similar to the resistance we now recognize that has followed the overuse of antibiotics. Killing vicunas will not solve the problem. Veterinarians must become a part of a solution that helps herders develop more sustainable parasite control programs, such as the creation of parasite refuges.21 Veterinarians routinely treat domesticated animals for a wide variety of internal parasites, but especially those that infect the digestive tracts of animals. Under most field conditions, conservation veterinarians would not treat free-ranging animals for parasites. Evaluating free-ranging species for internal parasites can provide early notice of a deteriorating ecosystem. Increased parasite loads often indicate stressed and poorly nourished animals, and heavy parasite loads can compromise immune systems. Because livestock growers often blame wildlife for infecting their herds with parasites, research should establish the parasite species that wildlife harbors and the ones that likely emanate from the livestock herds themselves. External parasites infect the skin, hair, scales, and feathers of animals. Many, such as ticks and leeches, strive to ingest the blood of the host animal. Others feed on the skin or flesh or animal, such as scabies, mange, and fly larvae. In Mongolia, we noted a possible linkage between unusually wet weather and the appearance of feather lice on Eurasian Black Vulture (Aegypius monachus) chicks. We have not examined whether these lice affect chick survivorship, but we plan to closely monitor this situation in the future. Many ectoparasites also act as vectors for zoonotic diseases, such as ticks that carry Lyme disease (caused by Borrelia spp. bacteria). Knowing which free-ranging species can act as a host for an arthropod vector can have important consequences for both domesticated animals and human health. In recent times, veterinarians have begun debating the efficacy and desirability of prophylactically treating seemingly healthy wild (and even domestic) animals for parasites.22 Wide use of such medicines may result in the evolution of parasites that are resistant to medicines, thus compromising our ability to treat
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animals that require help in battling dangerously high parasite loads. Medicines used to kill parasites can also produce deleterious secondary effects in the environment. For example, antihelmintic drugs provided to horses kill dung beetles that play a crucial role in recycling manure.22
Stress, Body Condition, and General Health Field veterinarians can help monitor the stress, health, and body condition of individuals in wild populations and collect valuable biological samples for further study. Monitoring the health status of individuals helps conservation programs assess a wide variety of factors, such as the effects of new research methodologies or conservation initiatives. For example, does a type of telemetry unit negatively affect individuals that wear it? As a specific example, we used veterinarians to assess the possible effects of a new telemetry backpack design we developed for vultures using captive birds. Do attempts to field vaccinate susceptible individuals cause more harm than good? Dr Rosie Woodroffe has studied the efficacy and possible side effects of a remotely delivered rabies vaccine for African wild dogs (Lycaon pictus).23-25 Rabies outbreaks have caused local extirpations of wild dog populations in the past, so field vaccinations promise to dramatically help African wild dog conservation, but we must ensure that such approaches do not inadvertently harm wild dogs in other ways. Equally important, animals brought into captivity to assist in establishing or maintaining “safety” populations of endangered species must undergo careful screening and quarantine to reduce the chances of introducing diseases and parasites into the captive population. Similarly, animal destined for reintroduction programs should undergo similar procedures to avoid transferring diseases or parasites from the source population (captive or wild) to the destination population.26 Increased stress can decrease survivorship and reproduction in animals. Stress also increases susceptibility to disease and parasitism. Research now focuses on assessing the levels of stress that individuals face and the methods of mitigating that stress. Increasingly, we have discovered that wildlife suffer from diverse problems owing to pollutants that humans release into the environment. Poisoning from DDT used to control insect populations thins raptor eggshells, reducing viability27 and lead from spent ammunition contaminates scavengers that eat shot carcasses and waterfowl that pick up spent lead pellets at the bottom of water bodies.28,31,32 Banning DDT has largely resolved that problem,27 but lead poisoning continues to frustrate efforts for conservation of California condor (Gymnogyps californianus) and other vulture species.29 Veterinary products used to treat domestic animals can sometimes produce harmful or deadly affects on wildlife, such as the massive vulture die-offs due to the use of diclofenac to treat livestock30,33 and dung beetle mortality from anthelmintic drugs used on livestock.22 Thus, we argue for the importance of conducting health screening on wild animals, including evaluating blood chemistries and titer for known problematic diseases when possible. Often, wild species can serve as sentinels to warn us of new disease and toxins in the environment.
Conclusions Increasing recognition of the importance of addressing animal disease and health issues in conservation programs has led to greater involvement by veterinarians. Indeed, we argue that interdisciplinary teams that include veterinary professions
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promise to greatly improve conservation success rates. Veterinarians can assist conservation projects in a variety of ways, but primarily to assist with animal capture and immobilization, assess wildlife health, and help mitigate the effects of wildlife diseases. Already field veterinarians play an important role in each of these areas, but as the number of endangered species continues to grow and as humans more commonly spread diseases and pathogens around the world, the contribution of veterinarians becomes ever more important.
Acknowledgments The Denver Zoological Foundation and Alameda East Veterinary Hospital supported our work. We thank the many people who assisted with various aspect of our thinking and work that contributed to this article including Sukh Amgalanbaatar, Cindy Bickel, Dr Diana Boon, Dr Tony DeNicola, Dr Glyn Maude, V. Veer, Ganchimeg Wingard, Earthwatch volunteers, and our many graduate students. References 1. Harthoorn AM. Problems and hazards of chemical restraint in wild animals. Inter Zoo Yearbook 8:215–220, 1968 2. Kock MD, Lance WR, Jessup DA. The art of chemical capture. Wild Prof 6:34–39, 2012 3. Kreeger TJ, Arnemo JM: Handbook of Wildlife Chemical Immobilization. 4th ed. Greyton, South Africa: International Wildlife Veterinary Services; 2007 4. Kock MD, Meltzer D, Burroughs R. Chemical and Physical Restraint of Wild Animals. Greyton, South Africa: International Wildlife Veterinary Services; 2006 5. Fowler Jr. FJ. Survey research methods (applied social research methods series no.1). 4th ed. Thousand Oaks, CA: Sage Publications, Inc; 2008 6. Nielsen L. Chemical Immobilization of Wild and Exotic Animals. Ames, Iowa: Iowa State University Press; 1999 7. Kenny D, DeNicola A, Amgalanbaatar S, et al. Successful field capture techniques for free-ranging argali sheep (Ovis ammon) in Mongolia. Zoo Bio 27:137–144, 2008 8. Fitzgerald KT, Vera R. Biotelemetry in reptiles. In: Mader D, editor. Reptile Medicine and Surgery. 2nd ed. St. Louis: Elsevier; 2006. p. 613–617 9. Diamond J. “Normal” extinctions of isolated populations. In: Nitecki M, editor. Nature. Chicago: University of Chicago Press; 1984. p. 191–246 10. Diamond J. Overview of recent extinctions. In: Western D, Pearl M, editors. Conservation for the Twenty-first Century. New York: Oxford University Press; 1989. p. 37–41 11. Wilson EO. The Diversity of Life. Cambridge, MA: Belknap Press; 1992 12. Matchett MR, Biggins DE, Carlson V, Powell B, Rocke T. Enzootic plague reduces black-footed ferret (Mustela nigripes) survival in Montana. Vector Borne Zoonotic Dis 10:27–35, 2010
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