Endangered wild animal populations are predisposed to threats of extinction arising from biotic pressure, habitat fragmentation, and even stochastic causes of extinction like epizootics. The highly endangered Asiatic lions (Panthera leo persica) may be faced with such threats. Such threats were evident from this study on captive Asiatic lions and other sympatrically occurring carnivores from western India, which were sampled from December 1998 to March 1999. Fifty-six Asiatic lions, including 17 hybrid lions (Afro-Asian crosses) from six captive centers in western India, were tested for antibodies against canine distemper virus (CDV), feline parvovirus (FPV), feline immunodeficiency virus (FIV), and feline leukemia viral (FeLV) antigen. Additionally, 37 leopards (Panthera pardus fusca), 30 domestic cats (Felis domesticus) and 196 domestic dogs (Canis familiaris) from the vicinity of the lions were tested for some of the above pathogens. Agar gel immunodiffusion (AGID) test and dot-immunobinding assay (DIA) were employed for CDV and FPV antibody detection. Commercial enzyme-linked immunosorbent assay (ELISA) kits were used for FIV antibody and FeLV antigen detection. Forty-nine of 56 lions (87.5%) were positive for CDV. Similarly, 33 of 37 leopards (89.2%) and 131 of 196 (66.8%) domestic dogs were positive for CDV. All 56 (100%) lions, 37 leopards (100%), and 30 domestic cats (100%) were positive for FPV antibodies. There were no detectable levels of FIV antibodies and FeLV antigens. It was observed that CDV and FPV, two viruses known to cause major mortality in captive carnivores, to be widely prevalent in these captive Asiatic lions and leopards. Domestic cats and domestic dogs also showed high and moderate levels of prevalence to FPV and CDV, respectively. It is suggested that these seropositive non-domestic carnivores may have the potential to pose a risk of infection to other seronegative animals. Hence any movement, translocation, or re-introduction of these animals must be planned after careful consideration and after subjecting them to standard quarantine and disease screening protocols. Lack of exposure to emerging and novel pathogens like FIV and FeLV would also be a risk and hence, identification of reservoirs and screening of in-contact animals is recommended. Vaccinations must be considered, using killed or other suitable viral vaccines, which have been proved to be safe, and effective in endangered felids. A combination of birth control, culling, and vaccination programs may be practiced for controlling the domestic cat and domestic dog populations in order to prevent any threats of infection.