What are tapeworms?
Tapeworms are flat, segmented, intestinal parasites of the cat and dog. They belong to a different class (Cestoda) than other intestinal parasites, such as hookworms and roundworms. Several types of tapeworms infect pets, but the most common species in dogs is Dipylidium caninum.
The tapeworm uses its hook-like mouthparts to anchor itself to the wall of the small intestine. Eventually, adult tapeworms reach lengths of up to 11 inches (30 cm).
As the adult tapeworm matures, individual segments (proglottids) break off from the main body of the tapeworm and pass in the dog’s feces. The segments look like grains of rice or cucumber seeds and are about ½-inch (12 mm) long and about 1/8-inch (3 mm) wide.
Occasionally, proglottids 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 dogs get tapeworms?
First, the dog inadvertently ingests a flea carrying tapeworm larvae. As the dog digests the flea, the tapeworm egg is released into the intestines, hatches, and then anchors itself to the intestinal lining. The tapeworm matures and produces eggs (in segments) that are excreted with the dog’s feces. Fleas ingest the eggs and then jump onto the dog, where the dog ingests them, and the life cycle begins again.
Dogs cannot become infected by eating tapeworm eggs. Tapeworms must first pass through the flea (the intermediate host) before they can infect the dog.
What are the clinical signs of tapeworm infection?
In puppies, heavy tapeworm infestation can cause stunted growth, anemia, and intestinal blockages. In dogs, tapeworms do not normally cause serious health problems. Occasionally, dogs will drag their bottoms on the ground, a behavior known as scooting, to calm irritation associated with the proglottids. Scooting can also occur for other reasons, such as impacted anal sacs. It is important to have your dog examined by your veterinarian if you notice your dog scooting. Rarely, 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 dog has tapeworms when they observe proglottids on feces or in vomit and brings this to the attention of their veterinarian. When segments of the tapeworm break off and pass into the dog’s stool, they can be seen crawling on the surface of the feces. Less commonly, segments are seen moving around the dog’s anus. Tapeworms are not readily diagnosed with routine fecal examinations.
How are tapeworms treated?
A deworming medication (parasiticide) may be given as a tablet or by injection. It causes the parasite to be digested in the intestines, so you normally will not see tapeworms passed in the stool. These drugs are very safe and should not cause any side effects. A variety of products are available to treat tapeworms in dogs, but they are not all equally effective. The most effective deworming products are only available by prescription from a licensed veterinarian.
"Flea control is critical for managing and preventing tapeworm infection."
Flea control is critical for managing and preventing tapeworm infection. Flea control involves treating the dog and the environment. If your dog lives in a flea-infested environment, reinfection with tapeworms may occur in as little as two weeks. Tapeworm medication is very effective, so recurrent tapeworm infections are almost always due to reinfection from fleas. Your veterinarian can recommend safe and effective flea control for your pet.
What is the prognosis?
The prognosis for successful treatment is excellent.
Can I get tapeworms from my dog?
Humans can become infected with Dipylidium caninum tapeworms, but infection is rare, because it requires ingestion of a flea. A few cases of tapeworm infection have been reported in children. Vigorous flea control will help eliminate any risk of children becoming infected.
Taenia is another common type of tapeworm that can infect dogs. These tapeworms use mice, birds, and rabbits as intermediate hosts. Dogs acquire Taenia infections by eating an infected host. Tapeworm medications are highly effective at eliminating these parasites. However, if your dog continues to hunt and eat prey, they can be reinfected and pass tapeworm segments in six to eight weeks. In dogs 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 disease when humans become infected.
Infection with this parasite is harder to diagnose than Dipylidium because the segments are small and not easy to see. Trappers and hunters in the north-central United States and south-central Canada may be at increased risk of infection with this worm when strict hygiene is not practiced. Foxes, coyotes, and wild rodents are important in this parasite’s life cycle.
Dogs may also become infected with Echinococcus if they eat rodents carrying the parasite. When Echinococcus are passed in the dog’s feces, humans are at risk of infection by inadvertent ingestion of the eggs. In humans, the disease is called hydatidosis, hydatid disease, or hydatid cyst disease, and it causes cysts to form in the liver.
Free-roaming 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 dog?
Tapeworms and pinworms look very similar. However, contrary to popular belief, pinworms do not infect cats or dogs. Any worm segments associated with dogs are due to tapeworms. Children who contract pinworms do not get them from cats or dogs.
