Can an indoor cat get worms?

Yes, is the answer to the question. Please read on. This is a complete page.

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The question asks whether a full-time indoor cat can become infested with parasitic worms which are called endoparasites. And the answer must be that they can but the chances of them becoming infested must be significantly lower than if they were indoor/outdoor cats. However, it is very difficult to totally eliminate the possibility of a cat ingesting the eggs of parasitic worms.

I’ll take three examples which are roundworms (ascarids), hookworms and tapeworms.

Parastic worms in cats
Picture in public domain or fair use.

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The last in the list, tapeworms, are the most likely to be found in indoor cat where they live in the small intestines. Both species of common tapeworm found in cats are transmitted by an intermediate host which is the cat flea or lice the case of the tapeworm with the scientific name: Dipylidium caninum. The flea harbours immature tapeworms in their intestines.

The other species of tapeworm, Taenia taeniaformis, is transmitted with the assistance of rodents, discarded animal parts, raw freshwater fish and uncooked meat.

Cat tapeworm segments and whole worms
Cat tapeworm segments and whole worms. Collage: PoC. Pics: in public domain. Drawing: Lifelearn Inc.

Fleas – external parasites (ectoparasites) – acquire the internal parasite i.e. the tapeworm by eating tapeworm eggs. The cat must bite or swallow the insect to become infested. This is likely to happen when they groom themselves if the cat has a flea infestation.

The lesson here is to make sure that the home is entirely free of fleas. And you can gauge whether this is the case for you flea comb your cat twice daily. If your cat is entirely free of fleas then I think it is fair to presume that your home is also flea-free. If not, you will have to conduct a holistic cleanup of your entire home as if engaging in a long-term war! You can start off by getting rid of all the carpets and making sure that your home has bare floors. Dramatic? Yes! Effective? Yes!

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Depending upon the arrangements, it is possible for an indoor cat to catch and eat a rodent because mice for example get into homes quite often. So that’s another way a full-time indoor cat could acquire the second species of tapeworm mentioned above.

Cat has a bug that looks like rice coming out of butt
Tapeworm segment looking like rice. Image: PoC.

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A full-time indoor cat might acquire the disease by ingesting infected faeces or they might acquire, rarely, the parasite but eating mice that host the larvae. The former method, would depend upon there being other pets in the home which are allowed outside, such as a dog.

CDC hookworm lifecycle illustration
CDC hookworm lifecycle illustration.

My research indicates that dogs and cats can get the same worms and therefore a dog could bring a hookworm into the home in their intestines, poop outside on a walk, walk in that poop which leaves the faeces on their feet and then the cat might inadvertently ingest a piece of those faeces and thereby ingest the larvae of the hookworm. That looks like a rather tortuous route but it seems to be possible to me.

Cat hookworm (Ancylostoma braziliense)
Cat hookworm (Ancylostoma braziliense). Photo: Science Photo Library.

Another possibility is that a cat has been adopted from a rescue center who is a carrier of the disease having recovered from it. Hookworm cysts might be in their tissue and during periods of stress the larvae can be released which would allow, it seems to me, the possibility of infecting other cats in a multi-cat home even when those cats are full-time indoors.


These are the most common worm parasites in cats occurring in a large percentage of kittens and in 25-75% of adults. The eggs of this parasite are very tough and they can live for months or years in the soil. Cats acquire the disease by ingesting the eggs. They can do this by eating a host animal such as a beetle or rodent which has acquired encysted larvae in its tissue. The larvae are then released into the cat’s gastrointestinal tract.

Roundworm. Image: PoC.


An indoor cat can get parasitic worms i.e. endoparasites in various ways but are less likely to do so than for an outdoor cat who can come into contact with the larvae of these worms more easily.

Some more on tapeworms

You might be able to tell if your cat has tapeworms my noticing tapeworm segments crawling in the fur around their bottom. This might not be always the case but it’s a good initial test. They live in the small intestines. They vary in length from less than 1 inch to several feet. The head fastens itself to the wall of the gut with suckers and hooks. The body is composed of segments. Each segment contains egg packets. The head must be destroyed to eliminate a tapeworm infection. Otherwise, the worm will regenerate.

The body segments containing the eggs are passed in the cat’s faeces. They are called proglotids. They are about .25 of an inch long.

Some more on roundworms

There are two common species of roundworms that infest the domestic cat. They live in the stomach and intestines. They can grow to 5 inches in length. If the eggs enter the cat orally, they hatch in the intestines. Larvae are carried to the lungs through the cat’s bloodstream. They become mobile in the lungs and crawl up the trachea where they are then swallowed. The cat might cough and gag at this time. This may be a symptom. They move to the intestines and develop into adults. This migration method is most common in kittens.

Other larvae encyst in tissues and remain dormant. In a breeding cat, during lactation, the dormant larvae are released. They re-enter the circulation and are transmitted to kittens in the mother’s milk. Both mother and kittens should be dewormed starting at about three weeks of age even when a faecal examination is negative because during lactation, she does not pass eggs in her stool.

Some more on hookworms

These are small thin worms about .25-.5 inches in length. They fasten themselves to the wall of the small intestines where they draw blood from the cat. There are four species of hookworm affecting the cat. They are more common in dogs than in cats. They are more common in areas that have high temperatures and humidity. This would be in the southern states of America for instance.

A cat acquires an infestation by ingesting infected larvae and as mentioned by eating mice that host the larvae. Symptoms are diarrhoea, anaemia, weight loss and progressive weakness. In a heavy infestation stools may be bloody and the prognosis for kittens is poor because it can be fatal. Many cats who recover from the disease can become carriers with cysts in their tissue. During periods of stress or illness an outbreak can occur.

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