Affected Animals:
Dogs and cats.

Overview: A common intestinal parasite, tapeworms do not cause harm to the dogs they infect, although minor irritation to the anal area may occur. There are two primary ways that dogs can become infected with tapeworms. Dogs can swallow a flea accidentally when they are chewing or licking themselves. If the swallowed adult flea contains infective tapeworm larvae, then the dog can become infected with the most common species of tapeworm, Dipylidium caninum. Less commonly, dogs can become infected when they eat a rabbit or rodent, which can harbor different species of the Taenia tapeworm.

The adult tapeworm is made up of many small segments called proglottids, each about the size of a grain of white rice. Usually, single proglottid segments -- which contain tapeworm eggs -- break off the tail end of the tapeworm, and are passed into the stool. These segments sometimes will remain visible on the dog's rear after it has had a bowel movement. They may also crawl out of the anus when the dog is very relaxed or sleeping.

Clinical Signs:
If many tapeworms are present, mild weight loss may occur. Other signs include scooting or dragging the rear end across the floor due to perianal pruritus and proglottids noted around the anus or in the feces. These segments can be moving or pasted to the perianal fur.

Symptoms:
If many tapeworms are present, mild weight loss may occur. Other possible signs include scooting or dragging the rear end across the floor due to mild irritation, and "white rice-like pieces" seen in the stool or around the anus. These segments can be moving or pasted to the fur.

Description: There are two species of tapeworms that affect dogs. Dipylidium caninum, which an animal gets by accidentally ingesting an adult flea containing the parasite, is the most common tapeworm found among dogs. Taenia species are transmitted to dogs that eat rabbits or rodents carrying these tapeworms. Neither type of tapeworm causes significant harm to canines, although minor irritation or itching of the anus may occur.

The adult tapeworm is composed of many small segments, called proglottids, and can reach a length of eight inches. The mature end segment of the tapeworm, which contains eggs, will break off and pass into the stool. These proglottids, which have been said to resemble "grains of white rice," may also appear on the animal's fur, near the anus.

Diagnosis:
The tapeworm infestation can be diagnosed if tapeworm segments, which look like grains of white rice, are visible in the stool or around the anus. In addition, a veterinarian may perform an examination of the tapeworm eggs under a microscope to determine the species of the tapeworm. Proglottids usually do not show up on a routine fecal flotation test because they are too big and heavy.

Prognosis:
With proper medical treatment, the prognosis is excellent.

Transmission or Cause:
Transmission of Dipylidium caninum tapeworms occurs when an animal swallows an adult flea that contains the tapeworm larvae. Ingesting a rabbit or rodent harboring the parasite results in transmission of the Taenia species of tapeworms.

Treatment:
Although most over-the-counter dewormers are not effective against tapeworms, an examining veterinarian can prescribe medications that are very effective and will dissolve the tapeworms. Tapeworms may return in two to three weeks after the medication is administered if fleas are not eliminated or if the animal continues to eat rabbits and rodents.

Prevention:
Prevention of tapeworms requires strict flea control. Dogs should be monitored to make sure they do not hunt rabbits or rodents. In addition, many new products are available for the prevention of both fleas and ticks.