Follow-up of the health conditions of an urban colony of free-roaming cats (Felis catus Linnaeus, 1758) in the city of Rio de Janeiro, Brazil

Similar to other urban areas where food and shelter are abundant, the zoological garden of Rio de Janeiro has dealt for years with a colony of feral or semi-feral domestic cats. A survey was conducted during 2002–2004 as a follow-up to a previous study in 2001 of the cat colony to identify pathogens circulating among the population and to annually follow the status of the cats to analyze morbidity coefficients and associations among infections and infestations identified in the colony. During the 3 years of the present study, 75 cats were sampled at least once, including 44 that were caught and examined only once, 14 that were examined twice, and 17 that were examined three times. For each cat that was caught, records were kept regarding sex, age, general health, and the presence of ectoparasites. Each year, a blood sample was taken for hematologic testing, platelet count, hemoparasite detection, antibodies to Toxoplasma gondii, and retrovirus detection. Blood counts were within normal range for the majority of cats tested. Feline immunodeficiency virus, fleas, and lice were detected in all years; however, incidence rates for each of these varied significantly throughout the years. Prevalence of Cytauxzoon spp., Mycoplasma spp., T. gondii infections were variable among the 3 years, although differences were not significant. Prevalence of feline leukemia virus increased significantly over the 3 years. Mycoplasma spp. and flea infestations were significantly associated, but no other associations among the pathogens were detected. Over the 3 years, the rate of new cat introductions decreased, and the pathogens showed a tendency to disseminate throughout the colony; however, there was virtually no evidence of clinically detectable disease. Therefore, it seems that stabilizing the population by a judicious control program facilitated the distribution of the pathogens throughout the colony, while the general well-being of the cats was not seriously affected.