Tigers (Panthera tigris), who once roamed across Asia, are now endangered and confined to <7% of their historic range.1,2 Of the six surviving subspecies, the Amur tiger (P. t. altaica) suffers from severe genetic and habitat impoverishment.3-8 Managed, captive Amur populations have the potential to infuse genetic diversity into wild populations. The success of captive breeding and reintroduction programs depends upon knowledge of the causes and consequences of disease processes in managed populations. Such information, although vital for developing effective diagnostic or preventative procedures and for subsequent epidemiologic monitoring and control, is scarce. We analyzed 265 Amur tiger necropsy reports (∼1/3 of all reported deaths between 1941–2008) from 61 North American zoos. The cumulative survival curve for males (n=119) did not differ significantly from that for females (n=146) (Kaplan-Meier, log-rank test, p=0.85). We assigned one of 12 primary causes of death or euthanasia (PCDE) to each tiger. Among immature (females: <3 years; males: <4 years), we found few sex differences in the occurrence and prevalence of PCDE, with ∼1/2 of all immature deaths attributed to perinatal causes (30.5%) or trauma (17.1%). However, we found marked sex differences in the occurrence and prevalence of diseases in adults. Among males, degenerative joint diseases (DJD; 31.2%) and neoplasia (29.9%) accounted for similar proportions of 77 deaths. Conversely, among females, neoplasia was the top PCDE, accounting for 46.2% of 106 deaths (with >65% of neoplasias affecting the mammary glands), while DJD accounted for only 8.5% of deaths.
The authors would like to thank Dr. Peter Fashing for his constant support and contributions and Dr. Kathy Traylor-Holzer for making this study possible.
1. Dinerstein E, Loucks C, Wikramanayake E, Ginsberg J, Sanderson E, Seidensticker J, et al. The fate of wild tigers. BioScience. 2007;57(6):508–514.
2. Morell V. Can the wild tiger survive? Science. 2007;317(5843):1312–1314.
3. Kitchener AC, Dugmore AJ. Biogeographical change in the tiger, Panthera tigris. Animal Conservation. 2000;3(2):113–124.
4. Luo S-J, Kim J-H, Johnson WE, van der Walt J, Martenson J, Yuhki N, et al. 2004. Phylogeography and genetic ancestry of tigers (Panthera tigris). PLoS Biol. 2(12):e442.
5. Mazák V. Panthera tigris. Mammalian species. 1981;152:1–8.
6. Miquelle DG, Darman Y, Seryodkin I. Panthera tigris ssp. altaica. IUCN Red List of Threatened Species: Version 2010.4. http://www.iucnredlist.org/apps/redlist/details/15956/0. 2010. Accessed May 13, 2011. (VIN editor: Link was not accessible as of December 9, 2020.)
7. Miquelle DG, Pikunov YM, Dunishenko VV, Aramilev IG, Nikolaev VK, Abramov EN, et al. 2005 Amur tiger census. Cat News. 2007;46:11–14.
8. Tilson R, Nyhus PJ. Tigers of the World: The Science, Politics and Conservation of Panthera tigris. 2nd Edition. Burlington, MA: Academic Press; 2010.