27th Annual Meeting and Symposium of the
Desert Tortoise Council, March 22-24, 2002
Abstracts

Potential Impacts of Captive Pet Tortoises on Wild Populations

Elliott R. Jacobson
College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610

The collection and importation of exotic chelonians for the pet trade, along with the maintenance of local native species has been accompanied by numerous reports in the literature of a variety of infectious and noninfectious disease problems in these animals. Imported exotics often arrive in poor health and thus allow certain latent infections to become active. Even locally collected chelonians when brought into captivity may break with certain infectious diseases because of stresses imposed upon these animals in a captive situation. Poor nutrition or an abrupt change from natural to commercially available foods may predispose these animals to emergence of infectious agents. Added upon this situation is the cross-contamination when different species are brought together in a common holding pen, whether at an exporter, importer, or ultimate owner of these animals. Pathogens in animals from different parts of the globe can intermix between their hosts and the potential for a disastrous infectious disease outbreak increases.

Chelonian recovery stations or conservation centers have developed in recent times as responses to dramatic decline of native turtle stocks, the huge number of displaced animals, unwanted pets, and confiscations. Centers have developed for tortoises and/or freshwater turtles in southern Europe, Africa, Northwestern Madagascar, India, and western North America. Often these centers, with meager funds, have impressive educational programs. Unfortunately, shortcuts are often the rule for captive management and repatriation elements of such conservation programs. Many centers lack special veterinary and herpetological expertise, and they can ill afford the expense of securing such support. In such situations, health screens and genetic assessments are often lacking, and rigid quarantine facilities are inadequate or absent. Repatriation protocols are generally developed without wildlife and veterinary science expert review. When a recovery center includes relocation, repatriation, or translocation exercises among its programs the motives for advocating these strategies must be carefully examined through peer review before the release and recommended pre- and post-release biological and management criteria are followed. It is imperative that projects be carefully monitored so that accurate results, either positive or negative, can be published.

It is clear from the literature that several pathogens have surfaced as the most significant infectious agents in chelonians, including tortoises. Mycoplasmosis, herpesvirus infection, iridovirus infection, and intranuclear coccidiosis are the most significant infectious diseases identified in these animals. With time, as more dead animals are examined in detail the list will probably grow.

Large numbers of desert tortoises are kept as pets throughout their range in the southwestern US. Many are kept in outdoor enclosures in areas where native populations exist. Desert tortoises owners also may be the owners of exotic tortoises which potentially harbor foreign pathogens. Mycoplasmosis and herpesvirus infections have been documented in captive tortoises and while information on the importance and presence of mycoplasmosis in wild populations has been building since its first description in 1991, we are just realizing the potential significance of herpesvirus in wild populations. While it is easy to focus on these two disease problems/pathogens of tortoises we must never lose sight that other pathogens may surface as more and more tortoises are kept as pets and become intensely managed. The public has been drawn to the importance of non-native emerging infectious diseases such as West Nile Virus infections in birds and humans in the eastern United States and the potential for something similar happening when a pathogen from captive tortoises, particularly non-native species, spreading into wild populations exist. Chiefly by education, this must be brought to the attention of those owners of these animals. The release of captive tortoises needs to be tightly controlled to keep this risk at a minimum.