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Intestinal Parasites – “Worms”


Hookworms are parasites, which get their name from the hook-like mouthparts they use to attach your cat’s intestinal wall. They are only about 1/8” long. Despite their small size, they suck large amounts of blood from the tiny vessels in the intestinal wall. Hookworms can cause severe anemia and even death in young kittens.


As their name implies, these are worms which have round bodies. On average, they are about 3-5 inches long. They live in your cat’s stomach and intestines and consume partially digested food. Roundworms are not as harmful as hookworms, but can cause weakness in adult cats and stunted growth in kittens.


Tapeworms are long, flat, segmented worms that look similar to rice. Tapeworms are relatively harmless, but can cause anal irritation and scooting. Their presence does indicate current or prior flea infestation.

How did my cat get worms?

Most commonly cats acquire intestinal parasites orally – by eating or licking objects contaminated with worms or worm larvae. Since cats are such excellent groomers, they can become infected by licking their paws after walking on contaminated feces (from the litter box or outdoors). Other sources are from the mother’s placenta or milk, or from ingesting infected wildlife (rodents, earthworms, cockroaches, fleas).

How are intestinal parasites diagnosed?

Intestinal parasites are diagnosed by finding worm eggs during a microscopic examination of your cat’s stool. Sometimes only a few eggs are passed into the feces, so examination of more than one stool sample may be necessary to find them. Occasionally, the adult worms can be found in the cat’s stool or vomit. Tapeworm eggs are very rarely seen on microscopic exam; they are usually diagnosed upon visual inspection of the anus or stool.

How are worms treated?

There are several very effective drugs that will kill intestinal worms:

  • Oral medication
  • Topical medication (new treatment for kittens only – one dose treats all 3 worms!)
  • Injection

Hookworms and roundworms need two treatments (unless the topical medication is used). This is because the medicine kills only the adult worms and so it is necessary to treat again in 3 weeks to kill any newly formed adult worms that were in the larval stage at the time of the first treatment

Tapeworms are usually cured with one dose of medication.

As the worms die, they are passed out in the feces, so you may see them in the stool.

Are feline intestinal parasites infectious to people?

Yes! Hookworm larvae can burrow into human skin. This causes itching, commonly called ground itch. Direct contact of human skin to moist, hookworm-infested soil is required.

The roundworm larvae of cats also pose a health risk for humans. 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 pets) for years.

People can get tapeworms if they accidentally ingest a flea.

How can I control worm infection in my cat and prevent human infection?

  • All kittens should be treated at least twice and then have a fecal exam to be certain no worms are present.
  • Prompt deworming should be given when parasites are detected.
  • Keep flea preventative on your cat monthly to prevent tapeworms transmitted by fleas.
    Some of the monthly heartworm preventatives for cats control hookworms and roundworms. Please ask a veterinary staff member which ones would be recommended for your cat.
  • Prompt disposal of cat feces should occur, especially in yards and playground. Cover sand boxes when not in use.
  • Strict hygiene is important especially for children. Do not allow children to play in potentially contaminated environments.
  • Pregnant queens should be dewormed in late pregnancy to reduce potential contamination of the environment for newborn kittens. They should also be treated concurrently with their offspring.
  • Cats with predatory habits should have a fecal examination twice yearly. Rodent control is desirable since rodents may serve as a source of roundworm and hookworms infection for cats.