What are tapeworms?
Tapeworms are flattened intestinal worms that are made up of many small segments, each about ¼ – ½ inch (3-5 mm) long. Unlike roundworms that live freely in the intestinal tract, tapeworms attach to the wall of the small intestine by hook-like mouthparts. Tapeworms are intestinal parasites of the cat and dog. Because they are classified as cestodes, they belong to a different family than the hookworms and roundworms which are called nematodes. Several types of tapeworms are known to infect dogs and cats, Dipylidium caninum, Taenia species, and Echinococcus. Dipylidium caninum is by far the most common one.
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 are developed from the head end and gradually mature, finally being shed at the opposite end, either singly or in short chains. These segments are passed in the feces when the 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 freshly passed feces. As the tapeworm segment dries, it becomes a golden color and the fertilized eggs are released into the environment.
Unlike roundworms, dogs and cats cannot become infected by eating fertilized tapeworm eggs. Tapeworms must first pass through an intermediate host, a flea (in the case of Dipylidium caninum), before they can infect a dog or cat. Taenia species infest the muscle of mice or herbivores (cows). The dog or cat becomes infected by ingesting the cyst that is in the muscle.
The tapeworm uses its hook-like mouthparts for anchoring to the wall of the small intestine. Eventually, adult tapeworms may reach several inches in length. As the adult matures, individual segments called proglottids break off from the main body of the tapeworm and pass into the animal’s feces. These proglottids are filled with up to twenty eggs.
Are certain cats or dogs more likely to get tapeworms?
Fleas are the intermediate host for the Dipylidium caninum. 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 may have seen fleas, the cat or dog must have ingested a flea in order to have tapeworms. Consequently, tapeworms are more common in environments that are heavily infested with fleas. Lice are also reported as intermediate hosts for tapeworms but they are relatively uncommon parasites of cats.
How do cats and dogs get tapeworms?
First, tapeworm eggs must be ingested by flea larvae, an immature stage of the flea. Contact between flea larvae and tapeworm eggs is facilitated by contaminated bedding or carpet. Adult fleas do not participate in this part of the tapeworm lifecycle. The infected flea larvae will mature into adult fleas.
Next, the cat or dog chews or licks its skin as an adult flea bites and swallows the flea. As the flea is digested within the cat’s intestine, the tapeworm hatches and anchors itself to the intestinal lining.
With Taenia species of tapeworm, the tapeworm eggs are ingested by a rodent or herbivore. The tapeworm forms a cyst in the muscle of the rodent or herbivore (cow) and when the dog or cat eats the muscle with the cyst inside, they become infected with the tapeworm.
What are the clinical signs of tapeworm infection?
Tapeworms may cause debilitation or weight loss if they are present in large numbers. A cat or dog 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. This behavior can be for other reasons such as impacted anal sacs as well.
In puppies and kittens, heavy tapeworm infestation can be more serious. Lack of growth, anemia and intestinal blockage can occur. Occasionally, the head of the tapeworm or scolex detaches from the intestinal wall. The worm can then be passed either in the feces or vomited. The full adult worm can be many inches in length.
How are tapeworms diagnosed?
Most commonly, 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 or cucumber seeds. When terminal segments of the tapeworm break off and pass into the animal’s stool, they can be seen crawling on the surface of the feces. Less commonly, they are seen crawling around the surface of the animal’s anus. Each of these proglottid capsules contains up to twenty tapeworm eggs.
When these proglottids are released into the environment, they dehydrate and harden, becoming smaller and taking on a golden hue. Eventually, they break open and release their contents. Be aware that tapeworms are often not readily diagnosed with routine fecal examinations. This is due to the weight of the egg sacs that prevents them from floating in the fecal float. In addition, tapeworm segments are only passed intermittently. Because of this, you should notify your veterinarian when tapeworm segments are found in your cat’s stool.
What is the treatment for tapeworms?
Tapeworm treatments are safe and usually very effective. The deworming medication called an anthelmintic may be given as a tablet, liquid, powder or an injection. After treatment, the tapeworm dies and is usually digested within the intestine, so worm segments don’t usually pass into the stool. Side-effects, such as vomiting and diarrhea, are rarely reported with the newer tapeworm medications.
Is there anything else I should do?
Flea control is the cornerstone of preventing tapeworm infection. At the Arbor Ridge Pet Clinic we can recommend safe and effective flea control for your pet. If your pet 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.
Additional recommendations include:
1. Prompt treatment when tapeworms are detected.
2. Appropriate disposal of all pet feces, especially in public parks, yard, or playgrounds.
3. Strict hygiene practices for children after playing outdoors.
What is the prognosis?
New medications are safe and effective. The prognosis for successful treatment is excellent. Prevention is a successfully accomplished by using a monthly flea preventive
Can I get tapeworms from my pet?
Contracting tapeworms from your pet is not common or likely. Dipylidium caninum, the most common tapeworm of the dogs and cats, 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 in the environment becoming infected.
Although Dipylidium species are the most common tapeworms in dogs, other Cestodes are also important in certain areas.
1.) Taenia species – These are tapeworms 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, birds, rabbits, hares, cows and sheep. The intermediate stages develop hyadatid cysts in various organs. We have excellent treatment for Taenia infections in pets.
2.) Echinococcus species – By contrast, these are very small tapeworms. They consist 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. Infection is by ingesting eggs that have originated from the feces of dogs, cats, coyotes or foxes harboring the adult tapeworm. Fortunately de-worming preparations, particularly those containing praziquantel are effective for eliminating the Cestode from the dog. These tapeworms cause serious, potentially fatal, disease when humans become infected. Rodent control and good hygiene are important in preventing the spread of this disease to humans.
Control measures to prevent tapeworm infection from Cestodes involve avoidance of uncooked or partially cooked meat or waste. This is why raw diets for pets are so risky.