In preliminary studies with Sarcocystis from bovine (Bos taurus) and mule deer (Odocoileus hemionus hemionus), a coccidia-free laboratory dog (Canis familiaris) and captive coyote (Canis latrans) were fed flesh from a local Sarcocystis-infected bovine and later flesh from an infected mule deer from Eastern Oregon. Sporocysts were passed in the feces of both canine hosts 10-15 days after ingestion of infected meat. There was a statistical difference in the size of sporocysts derived from bovine and deer. It was concluded that the Sarcocystis from bovine and mule deer probably constitute distinct species with a life cycle dependent on the respective ruminant host and a canine host.