Cats – Roundworms

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What are roundworms?

As their name implies, these are worms which have round bodies. On average, they are about 3-5 inches (7-12 cm) long. They live in the cat's intestines and consume partially digested food. Unlike hookworms, they do not attach to the intestinal wall; rather, they literally swim in their food. Roundworms, sometimes called ascarids, pass moderate numbers of microscopic eggs which are found in the cat's stool. Like hookworm eggs, they must be found with a microscope.

How did my cat get roundworms?

The major source of roundworm infection for kittens is the mother's milk. Roundworm larvae (immature worms) may be present in the mother cat's mammary glands and milk throughout the period of nursing the kittens.

Both kittens and adult cats may become infected by swallowing roundworm eggs (eggs picked up on the fur or feet from contact with infected cats' bowel movements) which contain infective larvae. The larvae hatch out in the cat's stomach and small intestine and migrate through the muscle, liver, and lungs. After several weeks, the larvae make their way back to the intestine to mature. When these worms begin to reproduce, new eggs will pass in the cat's stool, and the life cycle of the parasite is completed.

Obviously, roundworm eggs passed in one cat's stool may be infectious to other cats. Interestingly, a large number of other animal species have been found to harbor roundworms and represent potential sources of infection for cats. These include cockroaches, earthworms, chickens, and rodents.

What kinds of problems do roundworms cause for my cat?

They are not highly pathogenic (harmful) to adult cats, but large numbers can cause weight loss and a pot-bellied appearance to kittens and weak adults. Decreased appetite, vomiting, or diarrhea will be observed on occasion. Kittens will sometimes die with serious roundworm infections.

How is roundworm infection diagnosed?

Roundworms are diagnosed by a microscopic examination of the cat's stool. They pass a moderate number of eggs, so examination of more than one stool sample may be necessary to find them. Occasionally, the mature worms (they look like spaghetti) can be found by the guardian in the cat's stool or vomit.

How are roundworms treated?

Treatment is quite simple. Several very safe and effective drugs are available to kill roundworms in the intestine. Some of these drugs temporarily anesthetize the worms so that they pass out of the cat with a normal bowel movement. The live or dead worms are found in the stool. Because of their large size, they are easily seen.

At least two or three treatments are needed; they are typically performed at 2–3 week intervals. None of these treatments will kill the immature forms of the worm or the migrating larvae.

The eggs are highly resistant to most commonly used disinfectants and to even harsh environmental conditions. Therefore, removal of the cat's stool is the most effective means of preventing reinfection. A 1% solution of household bleach can be used to remove the sticky outer coating of the eggs, making it easier to rinse them away. This does not, however, kill the eggs.

Remember the obvious limitations about where bleach may be safely applied. If bleach is used in the cat's litterbox, be sure to rinse it completely since bleach is potentially toxic to cats.

 

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Are feline roundworms infectious to people?

Yes. The roundworms of both cats and dogs pose a health risk for humans. As many as 10,000 cases of roundworm infection in humans have been reported in one year. Children, in particular, are at risk for health problems should they become infected. A variety of organs may be affected as the larvae migrate through the body. In suitable environments, the eggs may remain infective to humans (and to cats) for years.

What can be done to control roundworm infection in cats and to prevent human infection?

• Pregnant cats should be dewormed in late pregnancy to reduce potential contamination of the environment for newborn kittens. Please bring in a stool on all pregnant cats.

• All new kittens should be examined for worms by a stool analysis. To effectively break the roundworm life cycle, kittens should be dewormed on the schedule recommended by your veterinarian.

• Prompt deworming should be given when any parasites are detected; periodic deworming may be appropriate for cats at high risk for reinfection. Adult cats remain susceptible to reinfection with roundworms throughout their lives. If you have any other cats in your household, they should also be dewormed.

• Cats with predatory habits should have a fecal examination several times a year. Rodent control is desirable since rodents may serve as a source of roundworm infection for cats.

• All cats should be examined yearly for worms by a stool analysis.

• Prompt disposal of all cat feces is important, especially in yards, playgrounds, and public parks.

• Stool should be removed from litter-boxes daily, if possible. Litter-boxes can be cleaned with a 1% bleach solution to remove roundworm eggs; rinse well to remove all bleach.

• Strict hygiene is especially important for children. Do not allow children to play in potentially contaminated environments.