What are tapeworms?
Tapeworms are flat, segmented intestinal parasites of the cat and dog. They belong to a different family (cestode) than other intestinal parasites, such as hookworms and roundworms, which are other common intestinal parasites of cats and dogs. Several types of tapeworms are known to infect pets, but the most common species observed in cats is Dipylidium caninum.
The tapeworm uses its hook-like mouthparts for anchoring to the wall of the small intestine. Eventually, adult tapeworms reach lengths of up to 11” (30 cm). As the adult tapeworm matures, individual segments (proglottids) break off from the main body of the tapeworm and pass in the cat's feces. The segments resemble grains of rice or cucumber seeds and are about 1/2” (12 mm) long and about 1/8” (3 mm) wide.
Occasionally, they can be seen moving on the hairs around the anus, or more commonly, on the surface of freshly passed feces. As a proglottid dries, it becomes a golden color and eventually breaks open, releasing the fertilized eggs into the environment. A proglottid may contain as many as 20 tapeworm eggs.
How do cats get tapeworms?
First, a tapeworm egg must be ingested by a flea larva (an immature stage of the flea). Once inside the larval flea, the tapeworm egg continues to develop as the larval flea matures into an adult flea. During grooming, or in response to a flea bite, the cat inadvertently swallows the flea. As the flea is digested within the cat's intestine, the tapeworm egg is released, hatches, and then anchors itself to the intestinal lining, therefore completing the lifecycle. Unlike other intestinal parasites, cats cannot become infected by eating tapeworm eggs. Tapeworms must first pass through the flea (the intermediate host) before they can infect the cat.
Are certain cats more likely to get tapeworms?
Tapeworms are more common in environments that are heavily infested with fleas. Cats that hunt intermediate hosts such as rodents, birds, and rabbits are at risk for other types of tapeworms covered later in this handout.
What are the clinical signs of tapeworm infection?
Usually, an infected cat’s owner will notice the presence of proglottids crawling on its feces. A cat will occasionally scoot or drag its anus across the ground or carpet due to the anal irritation caused by the proglottids; however, this behavior is much more common in dogs than cats. Occasionally, a tapeworm will release its attachment in the intestines and migrate to the stomach. When this happens, the cat may vomit an adult tapeworm several inches in length. Rarely, tapeworms may cause debilitation or weight loss if they are present in large numbers.
"...tapeworms may cause debilitation or weight loss if they are present in large numbers."
How are tapeworms diagnosed?
Most commonly, an owner recognizes that their cat has tapeworms through the observation of proglottids on feces or in vomit and brings this to the attention of the veterinarian. When segments of the tapeworm break off and pass into the cat's stool, they can be seen crawling on the surface of the feces. Less commonly, segments are seen moving around the cat's anus.
Tapeworms are not readily diagnosed with routine fecal examinations.
What is the treatment for tapeworms?
A deworming medication called an anthelmintic may be given as a tablet or an injection. After treatment, the tapeworm dies and is usually digested within the intestine, so worm segments do not usually pass into the stool. Side effects, such as vomiting and diarrhea, are rarely reported with newer tapeworm medications. A variety of products are available to treat tapeworms in cats, but they are not all equally effective. The most effective worming products are only available by prescription from a licensed veterinarian.
"...flea control is the cornerstone of the management and prevention of tapeworm infection."
If the cat lives in a flea-infested environment, tapeworm infection can reoccur within a few weeks, so flea control is the cornerstone of the management and prevention of tapeworm infection. Flea control products are convenient to use. Depending on the type of product and the presence of other pets in your home, you may also need to treat your house and yard for fleas (for further information see the handout “Flea Control in Cats”). With some newer products, environmental flea control may not be needed.
What is the prognosis?
The prognosis for successful treatment is excellent.
Are tapeworms from my cat dangerous to my family?
Humans can become infected with Dipylidium caninum tapeworms, although infection is rare because it requires ingestion of a flea. Most reported cases have involved children living in less-than-ideal conditions.
What other types of tapeworms can infect my cat and are they dangerous to my family?
The other common tapeworms that can infect a cat are members of a group called Taenia. The intermediate hosts of these tapeworms are mice, birds, and rabbits. Cats acquire Taenia infestations by eating an infected host. Tapeworm medications are highly effective at eliminating these parasites. However, if your cat continues to hunt and eat prey, reinfection can occur with the passage of tapeworm segments in six to eight weeks. In cats that hunt frequently, regular deworming is recommended.
"In cats that hunt frequently, regular deworming is recommended."
Another, less common, group of tapeworms called Echinococcus is of increasing concern as a threat to human health. These tapeworms cause serious, potentially fatal diseases when humans become infected. Infection with this parasite is harder to diagnose than Dipylidium because the segments are small and not readily seen. Trappers and hunters in the north-central United States and south-central Canada may be at increased risk for infection with this worm when strict hygiene is not practiced. Foxes, coyotes, and the wild rodents upon which they prey are important in the lifecycle of this parasite.
Dogs and cats may also become infected with Echinococcus 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. In humans, the disease is called hydatidosis, hydatid disease, or hydatid cyst disease, and results in cysts being formed in the liver. Free-roaming cats and dogs may need to be periodically treated with deworming medication. Rodent control and good hygiene are important in preventing the spread of this disease to humans. As with the more common tapeworm, Dipylidium, human infection with Echinococcus is rare, yet possible.
My child has pinworms. Did they come from my cat?
Tapeworms and pinworms look very similar. However, contrary to popular belief, pinworms do not infect cats or dogs. Any worm segments seen associated with cats are due to tapeworms. Children who contract pinworms do not get them from cats or dogs.