How common are worms in cats?

They're quite common. It's more common in cats that go outside because they have a higher exposure risk, but we see indoor-only cats with worms because of some of the reasons we talked about before—the potential exposure to dirt on your shoes. Up here in Maine, we have many old houses, and little mice can find their way in. Thankfully, cats are usually pretty good at catching those mice before they cause a problem, but with that also comes potential exposure to parasites.

Worms are fairly common. Tapeworms are the most common worms we see in cats. Kittens are the most affected, but adult cats are more prone to getting tapeworms from flea ingestion.

Very common in kittens. In fact, most kittens and puppies have intestinal worms, roundworms, and/or hookworms. That's very common in household cats. At least, once we get rid of the roundworms and hookworms, if you've got an exclusively inside cat, there's virtually no chance they would get them again because, as an adult, they can only get roundworms and hookworms from going outside and grazing and getting it from the grass. The larva lives around the grass in the dirt. As for tapeworms, they can get them from ingesting a flea, so if you should have any risk of exposure or getting fleas, or you've got other pets that come in the house and expose your indoor cat to fleas, they can absolutely get tapeworms. But again, they're not going to get the tapeworms from eating a small mammal unless you've got mice running around the house. If they consume a mouse, they can pick up the tapeworms that way, but if they're not going outside to hunt or catch chipmunks and mice and bowls and such, they're not going to get it any other way. Indoor cats can get intestinal worms, but it would only be the tapeworms as an adult.

Intestinal parasites are quite common, especially in kittens. Most kittens have some type of parasite when they join your family, so it's important to have them screened for worms and dewormed properly by a veterinarian.