What are tapeworms?
Tapeworms are flat, segmented intestinal parasites of the cat and dog. They belong to a different family than other intestinal parasites, such as hookworms and roundworms, which are the 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 called 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 the 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, it 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?
Fleas are the intermediate host for tapeworm. In other words, the tapeworm is unable to complete its life cycle without the presence of fleas in the environment. Regardless of whether the owner has seen fleas on the cat, or in the home, the cat must have ingested a flea in order to have tapeworms.
"Fleas are the intermediate host for the tapeworm, Dipylidium caninum."
Consequently, tapeworms are more common in environments that are heavily infested with fleas. It is recommended to treat your cat for fleas if tapeworms are noted, and use flea control to prevent future flea infestations and tapeworm infections.
What are the clinical signs of tapeworm infection?
Tapeworms are not particularly harmful to the cat and few clinical signs are attributed to their presence.
Usually, the cat is brought to the veterinarian because the owner notices the presence of proglottids crawling on feces. Rarely, tapeworms may cause debilitation or weight loss if they are present in large numbers. 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.
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. These proglottid segments look like grains of cooked white rice or cucumber seeds. Less commonly, segments are seen moving around the cat's anus.
You should note 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.
What is the treatment for tapeworms?
A variety of products are available to treat tapeworms in cats but they are not all equally effective. For the best advice on the type of deworming preparation most suitable for your cat, you should seek the help of your veterinarian. The most effective worming products are only available by prescription from a licensed veterinarian.
"After treatment, the tapeworm dies and is usually digested within the intestine, so worm segments do not usually pass into the stool."
The 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 the newer tapeworm medications.
Is there anything else that I should do?
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 you use 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 “Flea Control in Cats”). With some of the newer products, environmental flea control may not be needed. Circumstances vary however, so be sure to talk to your veterinarian.
"Flea control is the cornerstone of preventing tapeworm infection."
If the cat lives in a flea-infested environment, tapeworm infection can become re-established within a few weeks. This is very rarely due to treatment failure; in most cases, reappearance of tapeworm segments represents a re-infection of the cat. Additional recommendations include:
1. Promptly have your cat treated when tapeworms are detected.
2. Remove and dispose of all pet feces properly, especially in public parks, yards, or playgrounds.
3. Teach and practice strict hygiene practices for children after playing outdoors.
What is the prognosis?
New tapeworm medications and flea preventives are safe and effective. The prognosis for successful treatment is excellent. In most cases, prevention is successfully accomplished by using a monthly flea preventive.
Are tapeworms from my cat dangerous to my family or me?
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. The risk for human infection with this type of tapeworm is quite remote but does exist.
What are the other tapeworms that can infect my cat?
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, or rabbits.
"...cats acquire Taenia infestations by eating infected mice, birds, or rabbits."
In a similar manner to Dipylidium transmission, cats acquire Taenia infestations by eating infected mice, birds, or rabbits. Tapeworm medications are highly effective at eliminating these parasites. However, if your cat continues to hunt and eat prey, reinfection can occur with passage of tapeworm segments in 6-8 weeks. In cats that hunt frequently, regular deworming may be needed.
Another less common group of tapeworms called Echinococcus is of increasing concern as a threat to human health. These tapeworms cause serious, potentially fatal disease 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 life cycle 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.
Humans become infected through ingestion of the eggs, and may not show clinical signs until years after ingestion.
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.