Worms in cats: signs, types and how to keep your cat worm-free

Worms in cats are one of the most common health problems vets see. Cornell Feline Health Center says gut parasites affect as many as 45% of cats in some groups. Most worms are easy to treat and prevent, but they can make kittens seriously ill, and a few can spread to people. If you’re not sure how fast to act, our should I go to the vet check can help.

What kinds of worms do cats get?

The four worms that matter most for cat owners in the US are roundworms, tapeworms, hookworms and heartworm.

What are the signs of worms in cats?

Many cats with worms show no signs at all, which is why routine stool tests matter. Merck Veterinary Manual and Cornell list these as the most common signs when they do appear:

• A dull, scruffy coat
• A pot-bellied look, especially in kittens
• Diarrhea, sometimes with mucus or blood
• Vomiting, sometimes with worms in it
• Weight loss or poor growth in kittens
• Pale gums from blood loss (anemia)
• Irritation around the bottom
• Coughing, from roundworm larvae moving through the lungs, or from heartworm

Worms can also make a cat weaker and more likely to catch other infections, Cornell notes.

What are roundworms?

Roundworms are the most common gut worm in cats. Cornell says they affect 25% to 75% of cats, with higher rates in kittens. The adults are 3 to 5 inches long and cream-colored. They live free in the gut and feed on the food your cat eats.

Cats pick up roundworms by swallowing eggs from soil or feces, or by eating mice and other prey that carry the larvae. Kittens can get them through their mother’s milk soon after birth. International Cat Care says this route is so common that every kitten should be assumed to have roundworms.

Most adult cats cope with a light infection. Kittens are hit harder. Cornell says roundworms can cause vomiting, diarrhea, constipation and loss of appetite, and in severe cases life-threatening anemia.

What do tapeworm segments look like?

This is the sign most owners notice. Cornell describes tapeworm segments as flat, about a quarter of an inch long, and like grains of rice that stretch and shrink when fresh. Dried segments look like sesame seeds. You may see them stuck to the fur near your cat’s tail, on the poop or on bedding. They can also irritate the area around the bottom.

There are two common tapeworms in cats, and they come from different places:

• The flea tapeworm (Dipylidium caninum). Flea larvae eat the tapeworm eggs. Your cat then swallows an infected flea while grooming. International Cat Care says if your cat has fleas, assume it also has this tapeworm, and vice versa.
• The rodent tapeworm (Taenia taeniaeformis). Cats get it from eating infected mice and rats. It’s very common in cats that hunt.

Tapeworms rarely make cats seriously ill. But CAPC says treating them without also controlling fleas means your cat will probably get them again. See our guide to fleas on cats.

Stool tests often miss tapeworms, because the eggs are passed inside the segments. Tell your vet if you’ve seen segments, even if a test was negative.

What are hookworms?

Hookworms are thin, less than half an inch long, and too small to see in the poop. Cornell says they attach to the gut wall and feed on blood. They’re less common than roundworms, and how common they are varies a lot by region.

Cats usually pick them up when larvae in soil get through the skin or are swallowed. Mild cases may cause diarrhea and weight loss. Heavy infections can cause anemia and black, tarry poop from digested blood, and Cornell warns that severe blood loss can be fatal without treatment. Daily litter box cleaning helps control them.

Can cats get heartworm?

Yes, though it’s different from heartworm in dogs. Cornell explains that it spreads only through mosquito bites. In cats it mainly harms the lungs, and vets call this heartworm-associated respiratory disease (HARD). As few as 1 to 3 worms can cause signs.

Signs can look like asthma: coughing, gagging and fast or difficult breathing. Vomiting, weight loss and lethargy are common too. Some cats die suddenly.

Heartworm can’t be safely cured in cats, because the drugs used in dogs can be fatal to cats. That makes prevention the only real protection. Cornell advises that, with your vet’s approval, all cats get heartworm prevention. If your cat is coughing, see our guide to cat coughing.

Can indoor cats get worms?

Yes. Staying indoors lowers the risk but doesn’t remove it.

• Fleas get indoors on other pets and people, and bring flea tapeworms with them. Merck says flea control is critical for tapeworm control, even for indoor cats.
• Mice get indoors too, and cats that catch and eat them can pick up roundworms and tapeworms.
• Mosquitoes get indoors. CAPC reports that 25% to 30% of cats with heartworm were described by their owners as strictly indoor cats.

How often should a cat be dewormed?

It depends on your cat’s age, lifestyle and where you live, so your vet sets the plan, the product and the dose. The Companion Animal Parasite Council (CAPC), a US veterinary group, gives these general guidelines:

• Kittens: start deworming at 2 weeks of age and repeat it regularly until they move on to year-round parasite control.
• Pregnant and nursing mothers: keep them on broad-spectrum parasite control, to protect the kittens.
• Adult cats: year-round, broad-spectrum parasite control that covers heartworm, gut worms and fleas.
• Stool tests: at least four times in a kitten’s first year, and at least twice a year for adult cats.
• Heartworm: test cats before starting heartworm prevention, and after that as your vet advises.

International Cat Care adds that cats that hunt or go outdoors need more frequent worming than indoor cats. A product that covers tapeworms is needed if your cat has fleas. Deworming usually comes as a tablet, liquid or spot-on. Your vet can also check a stool sample, and our cat poop checker can help you describe changes before you call.

Can people catch worms from cats?

Some cat worms can infect people, and children are most at risk.

• Roundworms. CAPC and Cornell say Toxocara larvae can travel through the body and damage organs or the eyes. This is rare but can be serious, especially in young children. People get it by swallowing eggs from soil or dirty hands.
• Hookworms. Larvae in soil can get into human skin and cause an itchy, track-like rash.
• Flea tapeworm. Children occasionally get it by swallowing an infected flea. CAPC says it’s usually mild and easy to treat.

Roundworm eggs take 2 to 4 weeks in the environment to become infective, CAPC says, and then survive for years. So cleaning up promptly makes a real difference:

• Scoop the litter box every day, and wash your hands afterwards
• Don’t handle cat poop with bare hands
• Cover children’s sandboxes when not in use
• Wash hands after gardening, and teach children to wash after playing outside
• Feed commercial or cooked food rather than raw meat, as CAPC advises
• Keep your cat on the parasite control plan your vet recommends

Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.