Prevalence of dirofilarial infection in raccoon dogs in Japan.

The raccoon dog (Nyctereutes procyonoides viverrinus) is known to acquire canine heartworm (Dirofilaria immitis) infection. We surveyed the prevalence of heartworm infection in free-ranging raccoon dogs in the Nishi-Tama (Tokyo) and Kanagawa areas of Japan. A total of 75 raccoon dog carcasses, including 29 animals from the Nishi-Tama area and 46 from the Kanagawa area, were necropsied between 1992 and 1993. Eight out of 75 raccoon dogs were found to be infected (overall 10.7%). The prevalence of infection was 6 and 16% in Nishi-Tama and Kanagawa, respectively. Microfilarial production was observed in the uterus of one female adult dog.