While the internal parasites mentioned above do more damage to our beloved dogs, tapeworms have the highest level of owner recognition and horror factor. This may come from finding dried rice-like segments around your dog's tail or, heaven forbid, freshly passed wiggling tapeworm segments on your furniture or rug. Tapeworms are more often discovered at home, when segments are passed out of the anus, than by fecal checks. There are two common species of tapeworms found in dogs and a few unusual ones.

The Common Tapeworms

The most common tapeworms are Dipylidium caninum and Taenia pisiformis. These two tapeworms have different life cycles, and differentiating them is important for treating your dog and preventing future cases of tapeworm infestation. Dipylidium use fleas as their intermediate host. Dogs that have fleas often accidentally eat one while grooming and scratching. Taenia use rodents as their intermediate host, and dogs that hunt mice or rabbits can pick them up while hunting if they eat their prey. Clearly it is important to keep your dog flea-free and minimize hunting opportunities if you want to stay free of tapeworms.

The Less Common Tapeworms

There are other tapeworms that are seen in dogs. Echinococcus species can use northern rodents or sheep as intermediate hosts. While these tapeworms are not usually serious in dogs, they can lead to life-threatening cysts in the lungs and liver of people. Dogs that work sheep or that live in the northern part of North America should have periodic fecal checks for these parasites. (Fecal checks work better for this type.)

Diphyllobothrium is a large tapeworm seen in dogs from the northern half of the United States and Canada. This parasite uses fish as an intermediate stage and does not cause serious problems in dogs, but it can lead to serious anemia in people. This is another tapeworm species best diagnosed by fecal checks.