Diseases and Parasites of the Muskrat (Ondatra zibethica) in British Columbia

This investigation is based upon the examination of 205 muskrat carcasses taken at various times between October 1944 and May 1947 and derived from 17 different localities in British Columbia. Seventy-four per cent of these carcasses were parasitized by 13 species of internal parasites. These included: trematodes, Echinostomum coalitum, Echinoparyphium contiguum, Quinque-serialis quinqueserialis, Notocotylus urbanensis, and Plagiorchis proximus; cestodes, Hymenolepis evaginata and Hymenolepis octocoronata; nematodes, Capillaria ransomia, Trichuris opaca, and Hepaticola hepatica and a species of Acanthocephala, related to the genus Polymorphus (Family Corynosomidae). Two larval cestodes were found infecting the liver; the strobilocercus, Cysticercus fasciolaris (Taenia taeniaformis) and a proliferating cysticercus, Cladotaenia sp. Pathological lesions in the muskrats resulted from two different pulmonary infections, infections of wounds, and a type of tumor. It was found that: the muskrats in this province were not extensively parasitized; hence mortality due to excess parasitism is probably negligible. This paper includes a review of the parasites of the muskrat that have been recorded by other workers.