The Role of Veterinary Medicine in Endangered Species Conservation

Author(s): Michael Hutchins, Tom Foose and Ulysses S. Seal

Source: Journal of Zoo and Wildlife Medicine, Vol. 22, No. 3 (Sep., 1991), pp. 277-281
Published by: American Association of Zoo Veterinarians
Stable URL: http://www.jstor.org/stable/20095159
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 Journal of Zoo and Wildlife Medicine 22(3): 277-281, 1991
Copyright 1991 by American Association of Zoo Veterinarians

EDITORIAL

THE ROLE OF VETERINARY MEDICINE IN ENDANGERED

SPECIES CONSERVATION
Michael Hutchins, Ph.D., Tom Foose, Ph.D., and Ulysses S. Seal, Ph.D.

Current estimates suggest that between 1 combined result of disease and habitat al
and 5 million species of animals and plants teration can be catastrophic, as exemplified
may be lost in the next 2 decades, primarily by the two epidemics that decimated the last
because of habitat destruction and overex known wild population of black-footed fer
ploitation. Populations of large vertebrates, rets (Mustela nigripes). First, an outbreak
in particular, are being severely reduced, re of sylvatic plague devastated populations of
sulting in an increased vulnerability to ex their principal prey, the prairie dog (Cyno
tinction. The purpose of this editorial is to mys sp.). The final blow was delivered to
explore the current and future role of vet the ferrets themselves by canine distemper,
erinary medicine in endangered species con a disease that may have been introduced
servation and to summarize ways that zoo through contact with feral or domestic dogs.
and wildlife veterinarians can become in Of course, the fragmentation and reduction
volved in conservation efforts, giving spe of ferret populations had originally taken
cial attention to the veterinarian's evolving place because prairie dogs were considered
role in captive breeding and reintroduction pests and, consequently, were the focus of
programs. an intensive eradication program.
Some of the most significant threats fac One result of human meddling with eco
ing wildlife today are health related, includ logical systems is that many wildlife pop
ing illnesses that occur as a result of nutri ulations will have to be managed carefully
tional, behavioral, or physiological stress; if they are to survive, and veterinary med
contact with toxic substances; exposure to icine is sure to play an important role. Man
exotic disease agents; or reduced immunity agement concerns for the curator, wildlife
to endemic diseases. Biological hazards may manager, and veterinarian occur at three
result from contact with exotic or domestic different levels: the individual animal, the
species, humans (e.g., as a result of eco social group, and the population. At the in
tourism), or various human activities (e.g., dividual level, an animal must be kept
pollution from industrial waste). Even nor healthy so that it can survive, reproduce,
mal epidemiologic processes can over and rear its young. Attention to individual
whelm populations that have become very animals is especially critical in small captive
small and localized. Over time, a small, iso populations or in very small intensively
lated population can lose genetic variability, managed wild populations.
a factor that may be correlated with an in Clinical zoo veterinarians are the ulti
creased susceptibility to disease. Often, the mate generalists, using a diverse array of
information and skills to protect the health
of their charges or to restore health to com
From the American Association of Zoological Parks promised individuals. This work involves
and Aquariums, Conservation Center, 7970-D Old
paying close attention to an animal's fun
Georgetown Road, Bethesda, Maryland 20814, USA
damental nutritional and behavioral needs
(Hutchins); and the IUCN Captive Breeding Specialist
Group, 12101 Johnny Cake Ridge Road, Apple Valley, and being ready to identify and treat serious
Minnesota 55124, USA (Foose, Seal). health problems as they arise. Veterinary
277

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 278 JOURNAL OF ZOO AND WILDLIFE MEDICINE

training follows traditional trends in human lated stress can also compromise an ani
medicine, whereby considerable resources mal's immune system and thus increase its
are expended in sustaining individual lives. vulnerability to parasites or disease. Such
This perspective characterizes much of zoo problems tend to be most acute in captivity
veterinary medicine and is increasingly be because the animals are maintained in a re
ing applied to wild animals. Individual stricted space. Further research is needed
mountain gorillas {Gorilla g. beringei), for on the role of stress in animal health and
example, have recently been vaccinated reproduction and on the types of experi
against measles and treated for injuries in ences or situations that appear to trigger
nature. stress responses. Presently, no reliable mea
There is some concern that medical in sures are available for quantifying the effects
tervention of this kind may interfere with of stress on survival or reproductive ability.
natural evolutionary processes. Indeed, wild However, heart rate telemetry studies have
populations build up immunity because in been useful in assessing the effects of human
dividuals that survive epidemics live to pass activity on unhabituated wild animals. Heart
on their genes (and hence their ability to rate telemetry or other objective measures
resist disease) to the next generation. The may also be used to identify what causes
National Park Service supported this phi stress in captive animals. The results could
losophy when it failed to treat free-ranging have important implications for enclosure
bighorn sheep (Ovis canadensis) that con design; procedures used in animal capture,
tracted keratoconjunctivitis. The disease was handling, and shipping; feeding protocols;
thought to be naturally occurring, and many and the size and composition of social
animals subsequently became blind and groups.
died. In the case of the mountain gorillas, Finally, management decisions must be
however, with only about 350 animals re made at the level of the population or spe
maining, extraordinary measures including cies because the goals for conservation must
individual treatment may be justified. Con be developed at this level, both in the wild
sequently, a niche may be evolving for field and in captivity. In contrast with clinical
clinical veterinarians, and the clinical tech zoo veterinarians, wildlife veterinarians and
niques developed for the care of captive an epidemiologists tend to focus on the health
imals will be directly relevant to the treat and health-related problems of populations
ment of free-ranging animals. Continued rather than of individuals. In seeking to al
research will be necessary to develop diag leviate disease epidemics, these clinicians
nosis and treatment protocols for a wide may recommend manipulating habitats, al
range of species and to identify and catalog tering human activities, removing entire
the types of diseases to which various spe subpopulations, or developing mass inoc
cies are susceptible. The work of veterinary ulation or treatment procedures. Unfortu
pathologists will be especially important to nately, there has only been minimal overlap
this effort. between zoo and wildlife veterinarians in
With the survival of the individual ac recent years, and increased collaboration is
complished, it is then necessary to consider not only desirable but necessary.
each animal as the member of a social group When populations become fragmented
or breeding unit. At this level, behavioral and small, as occurs in captivity or in iso
considerations become essential, and more lated reserves, they must be managed to
collaboration between clinical veterinarians avoid genetic and demographic problems.
and behavioral scientists is necessary. For Because such problems are a function of
example, injuries, nutritional inadequacies, population size, a primary objective of any
and reproductive failure can result from ag management program must be to establish
gressive or competitive interactions. The re populations large enough to be viable. Vi

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 HUTCHINS ET AL.-ENDANGERED SPECIES CONSERVATION 279

able population size depends on both the breeding. Therefore, genetic management of
genetic and demographic objectives of the captive populations entails close regulation
program and the biological characteristics of who breeds with whom, how often, and
of the species in question. For most taxa, when. In terms of demographic manage
population sizes required for viability will ment, the objective is to increase the pop
be at least several hundred individuals, and ulation as rapidly as possible to its captive
this has had important implications for cap target population and then stabilize at that
tive breeding programs. Because space is level. Stabilization of populations is only
limited, population size must be strictly reg possible by regulating the number of ani
ulated if zoos are to provide a haven for a mals that are born or the number of animals
significant number of endangered taxa. For that depart from the managed population.
example, there are perhaps 500-600 man Veterinarians have expertise in the chemi
ageable spaces for tigers (Panthern tigris) in cal immobilization, sedation, and transpor
North American zoos. If the minimum vi tation of wild animals and are a critical
able population for a tiger subspecies is 175, component of cooperative breeding pro
then only three of the eight recognized sub grams. As reserves have become smaller and
species can be managed effectively in this more isolated, translocation of wild animals
region. Similar problems are experienced in has become necessary to maintain genetic
isolated reserves when population pressure diversity or to regulate population sizes.
causes animals to cross park boundaries or Thus, wildlife and zoo veterinarians must
when overpopulation results in damage to continue to develop effective means for
the ecosystem (e.g., as a result of overgraz safely capturing and transporting animals
ing by large herbivores). Thus, wildlife pop between different and sometimes distant lo
ulations often must be controlled, and cations.
methods of contraception are becoming in Genetic and demographic management
creasingly critical to this objective. Veteri of selected North American captive popu
narians are likely to be closely involved in lations is the responsibility of species sur
the testing and implementation of new and vival plans (SSP's) organized under the aus
innovative contraceptive techniques. pices of the American Association of
Among other things, these techniques will Zoological Parks and Aquariums (AAZPA).
have to be reversible (i.e., capable of being The SSP's are attempts by North American
activated or deactivated on demand), be ad zoos and aquariums to cooperatively man
ministered in a single application, and have age populations of endangered species to
an acceptable level of mortality. In addition, avoid the deleterious effects of small pop
they should not interfere with pregnancy or ulation size and to provide a hedge against
lactation nor adversely affect social behav extinction. The SSP's operate through mas
ior. In the case of wild animals, a predator ter plans that provide institution-by-insti
eating a treated animal should show no last tution and animal-by-animal breeding rec
ing contraceptive effects. Although it takes ommendations. In managed programs,
more time to realize the effects, fertility con every animal has a prescribed genetic con
trol can be more effective than culling, which tribution to the next generation, and after
can disrupt social structure and usually gen this contribution is made, each will even
erates a compensatory response in the pop tually be declared surplus to the program.
ulation, with a rapid return to original num One implication of the emerging conser
bers. vation mission of zoos is that their primary
One of the consequences of small popu perspective toward animals' needs is fo
lation size is that genetic diversity tends to cused on populations rather than on indi
be lost over time as a result of random sto viduals. However, there are circumstances
chastic processes (i.e., genetic drift) or in where these two perspectives may be in con

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 280 JOURNAL OF ZOO AND WILDLIFE MEDICINE

flict. For example, how should euthanasia cause of the high incidence of false positives
of healthy animals as a population man in the s?rologie test for this disease, animals
agement tool be viewed? Finding answers being prepared for release must be exam
to such questions will not be easy. Indeed,ined through a virus isolation test. Again,
the future of wildlife conservation may de there appear to be some uninfected herds
pend as much on our resolution of various in the United States, but should animals
ethical issues as it does on our knowledge from "unclean" herds (i.e., those that test
of biology and ecology. In terms of genetic positive) be moved into "clean" herds?
and demographic considerations, some in There will always be risks associated with
dividuals will be more important to the the movement of animals, but the devel
population than others. Thus, although he opment of improved technology could help
roic measures to save some individuals may to alleviate this problem. More reliable test
be justified, these measures may not be war ing procedures are needed to identify car
ranted in every case. Similarly, it may be riers. Translocation and reintroduction pro
extremely important to move an animal grams will also need to develop prophylactic
from one location to another to meet SSP treatment protocols for animals about to be
breeding recommendations, whereas there released. Work of this kind will assume add
may be veterinary reasons that argue against ed importance as the number of reintroduc
the move. The Cheetah SSP is confronting tions increases. The globalization of SSP's
just such a problem with feline infectious will also entail frequent movement of ani
peritonitis. The captive population contains mals from one geographic region to another,
some animals that test positive for this dis further increasing the need for such proto
ease and others that show no evidence of cols.
infection. Furthermore, some collections are Solutions to conservation problems are
composed only of "clean" animals, whereas going to require substantial research efforts.
in others, all animals may test positive for Although their clinical and administrative
the disease or there may be a mix. Where responsibilities often preclude their direct
can and should the tradeoffs and compro involvement in research, zoo veterinarians
mises be made between moving animals for have much to contribute in collaboration
genetic reasons and not moving them for with other specialists (e.g., in nutrition, be
disease control? havior, reproduction, and genetics). One of
Similar problems arise with translocation the most significant contributions has in
and reintroduction programs. Disease is an volved the collection of biological materials
important regulator of wildlife populations, that are used in a variety of scientific stud
and as individual animals are moved be ies. When and where valuable specimens
tween different populations or between cap cannot be kept alive, as much material as
tivity and the wild, there will be an in possible should be preserved, including se
creased risk of disease transmission. men, blood and tissue samples for genetic
Consequently, studies are needed to assess analyses, etc. Zoo and wildlife veterinarians
the health risks to both the target species must develop protocols for the collection of
and to wild coinhabitants in the release en such materials and must be aware of the
vironment. An excellent example is provid various samples that are required.
ed by the Arabian oryx (Oryx leucoryx). This Concerns about the welfare of animals
species, which became extinct in the wild have led to the development of various
in the 1960's is being returned from captiv guidelines for the use of animals in scientific
research. In most cases, these guidelines re
ity to its natural habitat in Oman. However,
Oman has strict regulations against the im quire veterinary involvement, especially
portation of blue-tongue disease, which is when invasive procedures are to be per
endemic in much of the United States. Be formed. In the United States, institutions

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 HUTCHINS ET AL.-ENDANGERED SPECIES CONSERVATION 28 1

that have formal research programs may be focus their attention on the following crit
required to form an Institutional Animal ical areas.
Care and Use Committee (IACUC). Such
1) Collection and analysis of necropsy data
committees are responsible for reviewing
for all SSP species.
research proposals and for ensuring that
2) Development of protocols for necrop
these proposals conform to the provisions
sies, disease surveys, and collection of
of the Animal Welfare Act of 1970. Vet
erinarians serve on these committees and biological samples for use in research and
routine health assessment.
are central to their deliberations.
Veterinarians have much to contribute to 3) Collection and dissemination of infor
mation on wildlife diseases and on the
wildlife conservation and can become more
diseases of domestic and feral animals
directly involved in many ways. The Spe
cies Survival Commission of the World that may impact wildlife populations.
4) Collection and analysis of data on the
Conservation Union (IUCN) has a Veteri
diseases of captive animals. This should
nary Specialist Group, which focuses on
include data on physiological norms,
many of the issues discussed above, es
mortality, causes of mortality, and in
pecially those related to wildlife diseases.
cidence of various diseases in captive
The IUCN's Captive Breeding Specialist
populations (e.g., as determined by s?
Group (CBSG) also has a Veterinary Work
rologie surveys, fecal examinations, etc.).
ing Group, which focuses on problems af
5) Development of effective methods of
fecting captive animals. Many SSP pro
prevention, diagnosis, and treatment of
grams have veterinary advisors, and as the
diseases that may prevent reintroduc
program continues to expand, the need for
tion efforts, including prophylactic
veterinary expertise will increase. More re
treatments for captive-bred animals that
cently, the AAZPA Conservation Program are scheduled for release.
has developed taxon advisory groups
(TAGs). These specialized committees are The distinction between captivity and the
responsible for regional strategic planning wild is disappearing. If current trends in hu
for specific taxa (e.g., felids, parrots, liz man population growth continue, habitats
ards). One of their most important func will be lost at a rapid rate, and remaining
tions is to assess the need for new studbooks wildlife populations will soon be restricted
and SSP's. Veterinary involvement is to national parks and equivalent reserves.
deemed critical at this level too, and several Some East African parks are now complete
TAG's now have veterinary advisors. ly surrounded by fences and have essentially
There are currently 56 SSP programs, and become megazoos. To preserve their wild
the AAZPA's goal is to have at least 200 by life, such parks will require intensive man
the year 2000. Nearly 40 TAG's have been agement similar to that practiced by zoo
formed or are in the early stages of devel logical gardens. The veterinary implications
opment. If each of these committees were of these developments will be enormous.
to appoint only one veterinary advisor, at Those who are interested should get in
least 240 individuals would be involved. volved now. Time is rapidly running out for
Thus, there is an immediate need for an wildlife, and if we fail to act collectively,
expanded veterinary involvement in SSP many culturally, economically, and ecolog
and related AAZPA and IUCN CBSG con ically important species will be lost forever.
servation programs, especially as it relates
to information gathering and analysis. More Received for publication 5 June 1991.
specifically, clinical zoo veterinarians should

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