What are tapeworms?
The most common tapeworm affecting dogs and cats is called Dipylidium caninum. Because they are classified as cestodes, these worms belong to a different family than hookworms and roundworms, which are called nematodes. Tapeworms attach to the small intestinal wall by hook-like mouth parts. Though tapeworms are actually made up of many small segments—each measuring about 1/8-inch long—adult tapeworms may reach up to eight inches in length. As the adult matures, the individual segments (proglottids) break off from the main body of the tapeworm and pass into the cat’s feces.
How do cats get tapeworms?
In order for a cat to become infected with tapeworms, he/she must ingest a flea that contains tapeworm eggs. This process begins when tapeworm eggs are swallowed by flea larvae (an immature stage of the flea). Contact between flea larvae and tapeworm eggs is thought to occur most frequently in contaminated bedding or carpet. Next, the cat chews or licks his/her skin as a flea bites and the flea is then swallowed. As the flea is digested within the cat’s intestine, the tapeworm hatches and anchors itself to the intestinal lining.
Lice are also reported as intermediate hosts for tapeworms, but they are relatively uncommon parasites of cats.
What are the clinical signs?
Tapeworms are not highly pathogenic (harmful) to your cat and few clinical signs are attributed to their presence. Though rare, tapeworms may cause debilitation and weight loss if they are present in large numbers. Occasionally, the cat may scoot or drag his/her anus across the ground or carpet because the segments are irritating to the skin in this area. However, this behavior is much more common in dogs. The adult worm is generally not seen, but the white segments that break away from the tapeworm and pass outside the body rarely fail to get an owner's attention! Occasionally, a tapeworm will release its attachment in the intestines and move into the stomach. When this happens, the cat may vomit an adult tapeworm several inches in length.
How are tapeworms diagnosed?
Most commonly, owners recognize that the cat has tapeworms and bring this to the attention of the veterinarian.
When terminal segments of the tapeworm break off and pass into the cat's stool, they can be seen crawling near the anus or on the surface of a fresh bowel movement. These segments look like grains of rice and contain tapeworm eggs, which are released into the environment when the segment dries. The dried segments are small (about 1/16-inch), hard and golden in color. Be aware that tapeworms are not readily diagnosed with routine fecal examinations. Because of this, you should notify your veterinarian when tapeworm segments are found in your cat’s stool.
How are tapeworms treated?
Treatment is simple and, fortunately, very effective. A deworming medication that kills the tapeworms is given, either orally or by injection. It causes the tapeworm to dissolve within the intestines. Since the worm is usually digested before it passes, it is not visible in your cat's stool. These drugs should not cause vomiting, diarrhea or any other adverse side effects.
Control of fleas is very important in the management and prevention of tapeworm infection. Flea control involves treatment of your cat, the indoor environment and the outdoor environment where the cat resides. If the cat lives in a flea-infested environment, reinfection with tapeworms may occur in as little as two weeks. Because the medication that treats tapeworm infection is so effective, return of the tapeworms is almost always due to reinfection from the environment.
Additional recommendations include prompt treatment when tapeworms are detected (periodic deworming may be appropriate for pets at high risk for reinfection), appropriate disposal of all pet feces (especially in yards, playgrounds or public parks) and strict hygiene practices for children after playing outdoors.
Are feline tapeworms infectious to people?
Yes, although infection is not common or likely. A flea must be ingested for humans to become infected with the most common feline tapeworms. Most reported cases have involved children. The most effective way to prevent human infection is through aggressive and thorough flea control. The risk for infection with this tapeworm in humans is quite small, but does exist.
A less common group of tapeworms, called Echinococcus, is of more concern. These tapeworms cause a very serious and potentially fatal disease when humans become infected. Infection with this parasite is harder to diagnose than Dipylidium because the segments are small and not easily seen.
Hunters and trappers in the North Central United States and South Central Canada may be at risk for infection if strict hygiene is not observed. Foxes and coyotes (and the wild rodents they prey upon) are important in the life cycle of this parasite.
Dogs and cats may also become infected if they eat rodents carrying the parasite. When eggs of Echinococcus are passed in the feces of the dog and cat, humans are at risk for infection. Free-roaming cats and dogs may need to be periodically treated with tapeworm medication. Rodent control and good hygiene are important in preventing the spread of this disease to humans. As with the more common tapeworm, infection with Echinococcus is infrequent but possible.
How can I tell tapeworms from pinworms?
Tapeworms and pinworms look very similar. However, contrary to popular belief, pinworms do not infect dogs or cats. Any worm segments seen associated with cats are due to tapeworms. Children who get pinworms do not get them from dogs or cats.
See Canine Tapeworm Infection