How Do Cats Get Worms? Types, Causes, and Prevention

Name: How Do Cats Get Worms? Types, Causes, and Prevention
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

Cats get worms in a few main ways: by swallowing parasite eggs from contaminated soil or litter, by eating infected prey like mice, by ingesting fleas that carry tapeworm larvae, and sometimes from their mother before or after birth. Each worm type has its own route into your cat's body, which is why prevention looks different for each one. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Roundworms are the most common intestinal worm in cats, and kittens can get them from their mother's milk [1].
Tapeworms almost always come from swallowing an infected flea, so flea control is tapeworm control.
Hookworm larvae can penetrate a cat's skin, and some hookworm species can infect people too [2].
Heartworm is spread by mosquito bites, not by contact with other cats, and it is harder to treat in cats than in dogs.
Ringworm is not a worm at all. It is a fungal skin infection that spreads by direct contact or contaminated objects.
Have your cat's stool tested at least once a year, and more often if your cat goes outside or you have kittens [3].

What "Worms" Actually Means in Cats

When owners say their cat has worms, they usually mean one of several very different organisms. Some are true intestinal worms you can sometimes see in stool or around the tail. Others live in the lungs, heart, or skin. A few things people call worms are not worms at all.

The most common intestinal parasites in cats are roundworms, hookworms, and tapeworms [3]. Heartworm is a different parasite that lives in the blood vessels and heart. Ringworm is a fungus that affects the skin and hair, and it has nothing to do with worms despite the name.

A large 2023 survey of fecal tests from client-owned cats across the United States found that 13.52% were positive for at least one parasite, and 2.10% had more than one type [4]. The most frequently detected parasite was Giardia, followed by the roundworm Toxocara cati [4]. That means worms and other parasites are common, even in cats that seem perfectly healthy.

How Do Cats Get Worms? The Routes That Matter

How do cats get roundworms?

Roundworms, also called ascarids, are the classic kitten worm. Toxocara cati is the most important species in cats, and it can infect people as well [1]. Cats pick up roundworms in three main ways.

First, a cat can swallow infective eggs from soil, litter, or anything contaminated with feces from an infected animal [1]. Second, a cat can eat prey such as mice that carry the parasite [1]. Third, kittens can get roundworms through their mother's milk [1].

Inside a kitten that has swallowed eggs, the larvae hatch, travel through the intestinal wall to the lungs, get coughed up, and are swallowed again to mature in the small intestine [1]. Adult worms can appear in a kitten's intestine as early as 3 to 4 weeks of age [1]. Adult cats usually have some resistance, but that resistance can drop around the time a queen gives birth, so she may shed large numbers of eggs in her stool [1].

How do cats get tapeworms?

Tapeworms are the worms you may spot as small, rice-like segments near your cat's rear end or in the litter box. The most common tapeworm in cats is Dipylidium, and the infection almost always starts with a flea.

Here is the chain of events. A flea larva eats tapeworm eggs. The flea matures and carries the tapeworm larva inside it. Your cat grooms, swallows the flea, and the tapeworm develops into an adult in the cat's intestine. This is why a cat with fleas is a cat at risk for tapeworms, and why treating the tapeworm without controlling fleas usually leads to repeat infections.

Cats that hunt can also get tapeworms from eating infected rodents or other prey. In one study of cats and dogs in southern Brazil, Dipylidium was the most common worm found in cats, present in 45.9% of the parasitized cats examined [5].

How do cats get hookworms?

Hookworms are small worms that attach to the lining of the small intestine and feed on blood. Cats can get hookworms by swallowing larvae from contaminated soil or by larvae penetrating the skin, usually through the paws or belly.

Hookworm infections can cause anemia, especially in kittens, and pale gums are a common sign. In the Brazil study, most parasitized animals had pale mucous membranes, including 71.6% of the affected cats [5]. Hookworms are also a public health concern. Some hookworm species, including Ancylostoma ceylanicum and Ancylostoma braziliense, can infect people and cause skin problems [2]. That is one more reason to take worm prevention seriously, even for an indoor cat.

How do cats get heartworm?

Heartworm in cats is spread by mosquitoes. A mosquito bites an infected animal, picks up heartworm larvae, and then bites your cat. The larvae travel through the cat's body and eventually reach the heart and pulmonary arteries.

Cats are not the natural host for heartworm, so the infection behaves differently than it does in dogs. A cat may have only a few worms, but even a small number can cause serious lung disease. There is no approved treatment to kill adult heartworms in cats, which makes prevention the main strategy. You can read more about this in Heartworm Prevention for Cats: Why It's Important and How It Works.

How do cats get ringworm?

Ringworm is a fungal infection of the skin, hair, and nails. It is not a worm, but it is grouped with parasite questions because it spreads easily and can pass to people.

Cats get ringworm through direct contact with an infected animal or person, or by touching contaminated bedding, brushes, furniture, or soil. Kittens, senior cats, and cats with weakened immune systems are most likely to develop it. Ringworm often looks like a round, bald, scaly patch, but it can also cause widespread hair loss or look like almost nothing at all. For a full breakdown, see Ringworm In Cats.

What do kittens get worms from?

Kittens have the highest risk of all. They can get roundworms from their mother's milk, and they can pick up hookworms and other parasites from a contaminated environment [1]. In one study, kittens under 6 months old had the highest infection rate at 36.17% [6]. That is why deworming schedules start early. Kittens should be dewormed on multiple occasions in the first 3 months of life, and some monthly heartworm preventives also prevent roundworm infection [1].

Signs Owners Notice

Worm infections can be silent, especially in adult cats. When signs do appear, they often include:

A potbellied or bloated look, most obvious in kittens
Weight loss or poor growth despite a good appetite
Vomiting, diarrhea, or both
Worms or rice-like segments in the stool or around the tail
Scooting or licking at the rear end
A dull coat
Pale gums, which can point to hookworm-related blood loss [5]
Coughing or breathing changes, which can happen with heartworm or with roundworm larvae moving through the lungs

Some cats show no signs at all and still shed parasite eggs that can infect other animals or people [3].

Causes and Risk Factors

The biggest risk factors for worms in cats are:

Going outdoors. Hunting, digging, and contact with contaminated soil all raise exposure.
Fleas. Fleas carry tapeworm larvae, so any flea infestation is a tapeworm risk.
Being a kitten. Kittens under 6 months had the highest infection rate in one study [6].
Living with an infected mother. Roundworms pass through milk [1].
Mosquito exposure. Any cat, indoor or outdoor, can be bitten by a mosquito carrying heartworm.
No deworming history. In one study of cats with no deworming history, 23.0% had intestinal worms [6].
Weakened immunity. Stress, illness, or a suppressed immune system makes it easier for parasites to take hold.

How Worms Are Diagnosed

Your veterinarian will start with your cat's history and a physical exam. The main test is a fecal exam. A fresh stool sample is mixed with a solution so parasite eggs float to the top, where they can be seen under a microscope.

Modern labs often combine several methods. A large U.S. study used centrifugal fecal flotation, coproantigen testing, direct fluorescent antibody testing, and Baermann examination to detect parasites [4]. That combination catches more infections than a single test.

Heartworm is diagnosed with a blood test, not a fecal test. Ringworm is often diagnosed with a Wood's lamp exam, a fungal culture, or a skin scraping.

Because parasite eggs are not shed every day, a single negative fecal test does not always mean your cat is worm-free. Your veterinarian may recommend repeat testing. Regular stool checks once a year or more are recommended, especially for kittens and outdoor cats [3].

Worm or Parasite	How Cats Get It	Main Sign	Prevention Focus
Roundworm	Eggs in soil, prey, mother's milk [1]	Potbelly, poor growth	Deworming, stool checks
Tapeworm	Swallowing infected fleas	Rice-like segments	Flea control
Hookworm	Larvae in soil, skin penetration	Pale gums, anemia [5]	Deworming, hygiene
Heartworm	Mosquito bites	Cough, breathing changes	Monthly preventive
Ringworm	Direct contact, contaminated items	Round bald patches	Cleaning, isolation

Treatment Options

Treatment depends on which parasite your cat has.

Intestinal worms. Your veterinarian will prescribe a dewormer matched to the specific worm. The dose is calculated from your cat's weight and health status, so never use a product meant for dogs or a human medication without veterinary guidance. Some monthly heartworm preventives also protect against roundworms [1].

Tapeworms. The tapeworm itself is treatable, but you also need to eliminate fleas. If fleas stay in the environment, your cat will swallow another infected flea and the cycle starts over.

Hookworms. Treatment usually includes a dewormer plus support for anemia if blood loss has been significant. Severe cases in kittens may need more intensive care.

Heartworm. There is no approved drug to kill adult heartworms in cats. Care focuses on managing symptoms and preventing new infections. This is why monthly prevention matters so much.

Ringworm. Treatment may include topical antifungal medication, oral medication, or both, along with environmental cleaning. Ringworm can take weeks to clear, and you should follow your veterinarian's plan closely because the infection can spread to people in the home.

If your cat has diarrhea along with a worm infection, see Cat Diarrhea with Worms: Causes and Treatment Options.

Recovery, Outlook, and Long-Term Management

Most cats with intestinal worms recover well once they are treated. Kittens may need several rounds of deworming because of their higher risk and ongoing exposure [1].

Long-term management means thinking about prevention, not just treatment. A few habits make a big difference:

Keep your cat on a year-round parasite preventive recommended by your veterinarian.
Test stool at least once a year, and more often for outdoor cats or kittens [3].
Control fleas on your cat and in your home.
Clean the litter box daily and wash your hands afterward.
Keep cats indoors when possible to reduce hunting and soil exposure.

Some parasites can cause disease in people. Toxoplasmosis can pass into cat droppings, and people can be exposed when they clean an infected cat's litter box [3]. Pregnant women, young children, and anyone with a weakened immune system are at higher risk [3]. If that describes someone in your home, talk with your veterinarian about the safest routine. You can also read Can Humans Catch Cat Worms.

Prevention

Prevention is simpler than treatment, and it works best when you combine a few steps.

Use parasite prevention all year. Monthly products can cover heartworm, roundworm, hookworm, and fleas. Your veterinarian will pick the right product for your cat's age, weight, and lifestyle.

Control fleas relentlessly. Tapeworms depend on fleas. Treat your cat and the environment, and keep up with it even in winter.

Scoop the litter box daily. This reduces the number of parasite eggs in your home and lowers the risk to people [3].

Wash your hands. After litter box duty, gardening, or handling a cat that goes outside.

Keep kittens on schedule. Kittens should be dewormed multiple times in the first 3 months of life [1]. Do not skip these visits.

Limit hunting. Indoor cats have far less exposure to prey and contaminated soil.

Test before you assume. A cat can carry worms without any signs. Yearly fecal testing catches infections early [3].

For heartworm specifically, prevention is not optional. There is no safe way to treat adult heartworm infection in cats, so the monthly preventive is the whole plan. Learn more in Heartworm Prevention for Dogs and Cats: What Owners Need To Know.

Limitations and When to Contact a Veterinarian

This article covers general information. Every cat is different, and individual cases need a veterinarian who can examine your cat, run tests, and prescribe treatment.

Contact your veterinarian the same day if your cat has:

Repeated vomiting or diarrhea that lasts more than a day
Visible worms in the stool or around the tail
Pale gums, weakness, or collapse
A kitten with a swollen belly and poor weight gain
Any signs of illness in a cat that is pregnant, nursing, or caring for kittens

Seek emergency care now if your cat is struggling to breathe, has blue-tinged gums, or cannot stand.

Schedule a routine visit if your cat has not had a fecal test in the past year, if you have seen fleas, or if your cat goes outdoors and is not on a parasite preventive.

Frequently Asked Questions

Can an indoor cat get worms?

Yes. Indoor cats can get heartworm from a mosquito that comes inside, tapeworms from a flea that hitchhikes in on your clothes or another pet, and roundworm eggs tracked in on shoes. Indoor life lowers the risk, but it does not remove it.

Can I get worms from my cat?

Yes, some cat parasites can infect people. Roundworm larvae can cause serious disease in humans, and some hookworm species can penetrate human skin [2]. Toxoplasmosis can spread through cat droppings, and pregnant women, young children, and people with weakened immune systems are at higher risk [3].

How often should my cat be tested for worms?

At least once a year for most adult cats, and more often for kittens, outdoor cats, or cats with a history of parasites [3]. Your veterinarian may recommend testing more frequently based on your cat's lifestyle.

Do I need to treat my whole house if my cat has worms?

It depends on the worm. For tapeworms, you must treat the fleas in your home or your cat will get reinfected. For ringworm, cleaning bedding, toys, and surfaces is part of treatment. For roundworms and hookworms, daily litter box cleaning and good hand hygiene go a long way.

Can worms in cats go away on their own?

No. Intestinal worms do not clear on their own, and untreated infections can cause weight loss, anemia, and serious illness, especially in kittens [6]. Heartworm in cats cannot be cured with treatment, which is why prevention matters so much. See your veterinarian for the right deworming plan.

References

Gastrointestinal Parasites of Cats - Cat Owners. Merck Veterinary Manual.
Imported zoonotic Ancylostoma ceylanicum and Ancylostoma braziliense infections in a cat in Romania. Parasites & vectors, 2026.
Parasites in Cats - Cat Owners. Merck Veterinary Manual.
Prevalence and epidemiologic patterns of feline parasitism detected by fecal examination in the United States, 2023. Veterinary parasitology, 2026.
Gastrointestinal helminthiases associated with cause of death in dogs and cats from southern Brazil. Veterinary parasitology, regional studies and reports, 2026.
Prevalence, risk factors, and zoonotic potential of gastrointestinal helminths in cats: A participatory epidemiological study. Journal of helminthology, 2026.