Tapeworms in Dogs

Tapeworm, artwork
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While tapeworms are rarely a serious health risk, they can pose problems like irritation and itchiness when they emerge from your pup's hind end (to say nothing about how gross they are!). It’s important to understand how your puppy contracts tapeworms to know how to get rid of the parasite and prevent its return.

What Are Tapeworms?

Tapeworms are ribbon-like flatworm parasites that live in the intestines of dogs, cats, and other animals. There are several varieties, but Dipylidium caninum and Taenia species are most common.

The head of the tapeworm is called the scolex or holdfast. It is equipped with hooks and suckers that are used to anchor it to the wall of the small intestine. Tapeworms do not have a mouth. Tapeworms don't even have a digestive system. Instead, they absorb nutrients through their body segments.

Called proglottids, these segments are linked together like a chain. The parasite continuously grows new segments that are added at the neck. Adult worms continue to add segments as long as they live, sometimes attaining terrifying lengths (anywhere from 15 centimeters to 20 meters!). They can be composed of hundreds of segments. Each proglottid contains both male and female reproductive organs. When mature, the segment produces hundreds or even thousands of eggs. Segments farthest from the scolex are the most mature and once "ripe" they are shed from the worm's body and pass in the puppy or dog's feces where they can be eaten by an intermediate host.

Immature worms must spend developmental time inside an intermediate host before being able to infest your dog. The flea serves this purpose for Dipylidium caninum while Taenia species require time in another vertebrate—often rodents, rabbits, and the like.

If your puppy is infested with fleas, it is also likely to have Dipylidium tapeworms. Tapeworm eggs are eaten by the flea larvae, which then develop as the flea itself matures. When a pet nibbles to relieve that itch, it often swallows the flea and infects itself with tapeworm.

Animals that are allowed to hunt are at the highest risk for Taenia tapeworms.

Symptoms of Tapeworms in Dogs

Once outside the body, segments can move independently like tiny inchworms for a period, but when dry they look like grains of rice. Infested pups typically have segments stuck to the hair surrounding the anal area or in their bedding. Eventually, the segments dry and rupture, releasing the eggs they contain into the environment. Tapeworm eggs are passed and shed sporadically. A veterinary examination of the pup's stool for eggs may often be inconclusive. It's considered diagnostic to find the segments on the pet.

Tapeworms are rarely a medical problem and are usually considered an unpleasant annoyance. The moving proglottids may irritate the anal region, which may prompt dogs and puppies to excessively lick themselves or "scoot" their rear against the floor or ground. In rare cases, puppies may develop a gastrointestinal impaction due to the presence of large numbers of worms.

Treatment and Prevention of Tapeworms

There are several safe and highly effective treatments for tapeworms, which may be administered as a pill, injection, or spot-on. Some must be prescribed by a veterinarian while others are available over the counter. A one-dose treatment will eliminate the tapeworms, but dogs can be reinfected immediately. Controlling fleas and preventing hunting are the best ways to prevent tapeworm infestation.

Human Health Risk

There is a human health risk associated with some tapeworms that can affect dogs. People (usually children) can contract Dipylidium tapeworms from eating an infected flea. While not common in dogs, Echinococcus granulosis tapeworms occasionally infect people in Alaska and the southwestern United States causing cysts to form in the liver, lungs, and sometimes other organs.

Echinococcus multilocularis can be found in the north-central United States and Alaska. Although human infections are rare, they can be deadly due to the formation of destructive tumors in the liver. Check with your veterinarian to see if these types of tapeworms pose a risk in your area.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
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  1. Tapeworm Infections in Dogs. VCA Hospitals.

  2. Tapeworm Infection in Dogs. VCA Animal Hospitals.

  3. Dipylidium FAQs. Centers for Disease Control and Prevention.

  4. Tapeworms and Hydatid Diseases. Department of Health, State Government of Victoria.