Attempted Transmission of Oslerus (Oslerus) osleri (=Filaroides osleri) from Coyotes to Domestic Dogs and Coyotes

Oslerus (Oslerus) osleri (=Filaroides osleri) is a widely occurring, tracheal parasite of wild canines (Holmes and Podesta, 1968, Can. J. Zool. 46: 1193-1204; Thornton et al., 1974, J. Wildl. Dis. 10: 232-236; Morrison and Gier, 1978, Ibid. 14: 314-316; Samuel et al., 1978, Can. J. Zool. 56: 2614-2617; Pence and Meinzer, 1979, Int. J. Parasitol. 9: 339-344). In domestic dogs, 0. osleri has been reported from several continents, but is uncommon (Mills, 1967, J. Sm. Anim. Pract. 8: 37-43). Little is known of the natural life cycle of 0. osleri (Mills, loc. cit.), but 0. osleri has been experimentally transmitted directly from dog to dog using first stage larvae (Dorrington, 1968, Onderstepoort J. Vet. Res. 35: 225-285; Polley and Creighton, 1977, Vet. Rec. 100: 136-137). Price (1928, J. Parasitol. 14: 197) suggested that dogs were accidental hosts for 0. osleri, the normal hosts being wild canines; however, attempted transmission of 0. osleri from coyotes (Canis latrans) to domestic dogs has not been reported. The purpose of this study was to compare the success of direct transmission of 0. osleri (coyote origin) in coyotes and domestic dogs. Rats also were inoculated with larvae (coyote origin) to determine a possible role of rodents as transport or paratenic hosts. Large nodules containing live adult 0. osleri were separated from the tracheal mucosa of a wild-caught, adult coyote from Whitman Co., Washington. Adult female worms were teased apart and macerated in a small quantity of 0.95% phosphate-buffered saline (PBS). Embryonated eggs were washed through a 100-mesh sieve into a 250-ml beaker with 150 ml PBS. Eggs were stored at room temperature (25 ? 2 C) in a covered beaker and were examined on days 6, 7, and 8, by which time many eggs had hatched to motile 1st stage lar