Tapeworm Infection in Dogs
What are tapeworms?
Tapeworms are flat intestinal worms that are made up of many small segments, each about ¼ - ½" (3-5 mm) long. Unlike roundworms that live freely in the intestinal tract, tapeworms attach to the wall of the small intestine using hook-like mouthparts.
Tapeworms belong to the cestode family of intestinal worms. The most common tapeworm of dogs and cats is Dipylidium caninum. The adult worms may reach up to 8 inches (20 cm) in length. The individual segments begin to develop starting behind the head and move down the tapeworm as they gradually mature, finally being shed at the opposite end, either singly or in short chains. These segments, called proglottids, are passed in the feces when an infected dog defecates. They are about 1/8" (3 mm) long and look like grains of rice or cucumber seeds. Occasionally they can be seen moving on the hairs around the anus or on the surface of freshly passed feces. As the tapeworm segment dries, it becomes a golden color and eventually breaks open, releasing the fertilized eggs into the environment.
Unlike roundworms, dogs cannot become infected by eating fertilized tapeworm eggs. Tapeworms must first pass through an intermediate host (a flea) before they can infect a dog.
How do dogs get tapeworms?
When the infected eggs are released into the environment, they have to be swallowed by immature flea larvae in the environment. Once inside the larval flea, the tapeworm egg continues to develop as the flea matures into an adult flea. During grooming or in response to a flea bite, a dog can ingest the tapeworm infected flea and complete the life cycle.
Are tapeworms dangerous for my dog?
Tapeworms do not normally cause serious health problems in dogs. Occasionally dogs will drag their bottoms on the ground, a behavior known as scooting, in order to allay this irritation. Note that scooting can also occur for other reasons such as impacted anal sacs.
In puppies, heavy tapeworm infestation can be more serious. Lack of growth, anemia and intestinal blockages can occur. Occasionally, the head of the tapeworm or scolex detaches from the intestinal wall; the entire adult tapeworm will then be passed in the feces or vomited up.
How is a diagnosis made?
Clinical diagnosis is usually made by observing the white mobile tapeworm segments in the feces or crawling around the anus. They often look like grains of rice.
Tapeworm segments are only passed intermittently and therefore are often not diagnosed on routine fecal examination. If you find any segments, white or golden color, bring them to your veterinarian for a definitive diagnosis.
What is the treatment?
With today's drugs, treatment is simple and effective. The parasiticide may be given either in the form of tablets or by injection. It causes the parasite to dissolve 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.
Is there anything else I should do?
"Flea control is critical in the management and prevention of tapeworm infection."
Flea control is critical in the management and prevention of tapeworm infection. Flea control involves treating the dog and the environment (for more information, see the Client Handouts: Flea Control in Dogs and Flea Control in Cats).Your veterinarian can recommend a safe and effective flea control for your pet. If your dog lives in a flea-infested environment, re-infection with tapeworms may occur in as little as two weeks. Since tapeworm medication is so effective, recurrent tapeworm infections are almost always due to re-infection from fleas and not failure of the product.
Can I get tapeworms from my dog?
You cannot get tapeworms directly from your dog. Dipylidium caninum, the most common canine tapeworm, depends on the flea as the intermediate host. A person must swallow an infected flea to become infected. A few cases of tapeworm infection have been reported in children. Vigorous flea control will also eliminate any risk of children becoming infected.
Although Dipylidium species are the most common tapeworms in dogs, other cestodes are also important in certain areas.
Taenia species - These are tapeworms that are acquired by eating prey or waste containing the infective larval stage. These are much larger tapeworms, often up to one yard (one meter) in length. Intermediate hosts include rodents, rabbits, hares and sheep. The intermediate stages develop hydatid cysts in various organs in the intermediate host. There are effective medications that will eliminate Taenia infections in dogs. If your dog eats prey such as rodents or rabbits, re-infection can occur with passage of tapeworm segments in 6-8 weeks.
Echinococcus species - These are very small tapeworms, consisting of only three or four segments, and are usually less than 3/8" (1 cm) in length. Intermediate hosts can be sheep, horses and occasionally man. In humans the disease is called hydatidosis, hydatid disease, or hydatid cyst disease, and results in cysts being formed in the liver. The disease is very rare in the United States, but has been reported in California, Arizona, New Mexico and Utah. Humans are infected by eating contaminated meat or by accidentally ingesting eggs that have originated from the feces of dogs, coyotes or foxes harboring the adult tapeworm. Fortunately, de-worming preparations, particularly those containing praziquantel, are effective for eliminating this cestode from infected dogs.
Prevention of cestode tapeworm infection involves avoidance of uncooked or partially cooked meat or meat by-products.
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