Spotlight on Zoo Science
March
10, 2004
Fatal Interaction: Pets Imperiling Wild Populations
National Zoo scientists are studying how domestic cats and dogs might expose endangered wild carnivores to devastating deadly diseases.
In the past few years global attention has been focused on the risks of diseases jumping from wild animals to people, with sometimes fatal consequencesSARS is a prime example. But people, through the agency of their domestic animals, also bring diseases to wild animals as they move ever more deeply into once-remote wildlands. Increasingly, scientists are recognizing this as a serious threat, especially to endangered species that can little afford the ravages of an epidemic disease.
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| Disease spillover from domestic animals threatens lion populations in Africa. |
In Africa, for instance, lions, Ethiopian wolves, and African hunting dogs have suffered well documented population declines as a result of diseases caught from domestic dogs. Recently, disease organisms in domestic cat feces, which contaminates near-shore ocean waters via discarded kitty litter, have been implicated in the decline of sea otters off the coast of California. Up to now, however, the extent of the potential problem in South America has been little explored.
In a 2004 paper in the journal Animal Conservation**, National Zoo veterinarian Sharon L. Deem and her colleagues reported on their investigation of the potential for the diseases of domestic cats and dogs to spillover into populations of wild carnivores, including bush dogs, jaguars, pumas, ocelots, and other small cats, in Bolivia's Madidi National Park. The World Conservation Union lists all of these species except the puma as threatened.
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| Sharon L. Deem (left) and her colleagues draw a blood sample from a domestic dog. |
The scientists collected blood samples from 40 dogs and 14 cats (cats aren't popular as pets here) living in three different villages in the buffer zone around the rainforest park. They then tested the samples for the presence of antibodies to nine different pathogens of dogs and nine pathogens of cats.
Antibodies would indicate that the animals were infected with the pathogen, or had been infected with it in the past, giving the scientists a measure of how common the pathogen is in the domestics, and thus of the chance that wild animals could be exposed to it through direct contact with an infected animal or its urine and feces. Both dogs and cats roam freely in these villages and dogs regularly accompany hunters into the forest.
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| Bush dogs are at risk of catching domestic dog diseases. |
The results, especially those for dogs, are worrisome. More than 90 percent of the domestic dogs had antibodies for canine distemper virus and canine parvovirus. Canine distemper has already been implicated in serious epidemics among carnivores.
For example, this virus was responsible for an epidemic among Serengeti lions that reduced this population's numbers from about 3,000 to 1,000 to in the mid-1990s. Canine parvovirus is also know from wild canids, although this often fatal disease's effects on wild populations are not well understood.
At least some dogs also had antibodies to the other seven pathogens, although scientists believe these may be less likely to cause epidemics among wild carnivores. However, onethe parasite that causes mangehas resulted in population declines in raccoons and coyotes, and antibodies to this pathogen were present in more than half the dogs examined.
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Ocelots are among the threatened cats of Bolivia's Madidi National Park. |
Among the domestic cats, none had antibodies to three of the nine cat pathogens, including two pathogens potentially most dangerous to wild cats. However, all had antibodies to feline panleukopaenia and all but one to feline calicivirus. Both of these pathogens are known to cause disease in wild cats.
Extensive vaccination programs among domestic dogs and cats in Europe and North America have made disease spillover from domestic carnivores to wild ones rare. Where the spillover has been obvious to scientific observers, as it has been in the cases of the African savanna carnivores, intensive vaccination efforts in nearby local communitiescreating a buffer zone between wildlife and unvaccinated domestic animalsseem to have been successful.
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| Epidemics among wildlife may be overlooked in the rainforest. |
In the dense rainforests of the Amazon Basin, disease outbreaks among wild animals are likely to be overlooked. However, the results of this study indicate that disease spillover from domestic cats and dogs to wild carnivores is a real possibility.
To reduce the risk to endangered species, conservationists must device strategies to increase vaccination rates among domestic animals living near protected areas and to educate local people about how their free-ranging pets threaten wildlife.
—Susan Lumpkin
Reference
Fiorello, C.V., S.L. Deem, M.E. Gompper, and E.J. Dubovi. 2004. Seroprevalence of pathogens in domestic carnivores on the border of Madidi National Park, Bolivia. Animal Conservation 7:45-54.
Sharon Deem completed this project while she was with the Wildlife Conservation Society. She is continuing her studies of domestic animal disease and their impact on wildlife diseases, focusing on foxes, maned wolves, and domestic dogs, at another South American site.
Note to Media: If you would like more information about her current project, or any of the Zoo's conservation and science programs, please contact the Zoo's Office of Public Affairs.
