Induced Toxoplasma gondii, Toxocara canis, and Isospora canis infections in coyotes

Six littermate laboratory-raised coyotes (No. 1-6) were used to study the transmission of Toxoplasma gondii from cats and mice, and Toxocara canis and Isospora canis from dogs and mice. Coyotes 1 and 2 were inoculated orally with 1,000 infective oocysts of the TC-1 strain of T gondii; coyotes 3 and 4 were fed mice infected with tissue cysts of the TC-1 strain of T gondii. Eight days after inoculation with T gondii, the same 4 coyotes were exposed to Toxocara canis: coyotes 1 and 2 were inoculated orally with 500 embryonated eggs, and coyotes 3 and 4 were fed mice infected with Toxocara canis. Fifteen days after exposure to Toxocara canis, the same 4 coyotes were fed mice infected with I canis. Two coyotes (No. 5 and 6) did not receive any organism and they served as controls. All 4 inoculated coyotes remained clinically normal but became infected with all 3 organisms. Toxoplasma gondii was recovered from the brain, heart, diaphragm, and muscles of limbs of coyotes killed 49 and 66 days after inoculation with oocysts, but only from muscles of limbs of coyote 4, killed at 84 days, and from the brain and muscles of limbs of coyote 3, killed at 72 days after feeding infected mice. Control coyotes did not acquire any of the 3 infections.