Cat Worms

"Cat worms are parasites that enter your cat. They can be contracted from a mosquito bite (heartworm), from eating eggs (roundworm) or from the ground or water (hookworm). Treatment for hookworms usually kills roundworms as well. Cats are only treated for heartworm if they show symptoms."

There are many kinds of worms that can affect your cat. Each type of parasite (another name for worms) has its' own characteristics. Worms vary in size and how they affect your cat.  Not every cat will show symptoms after contracting worms.

Younger, intact and mix breed cats have a higher prevalence rate for both roundworms and hookworms. Roundworm infection are more common in summer, fall and winter, while hookworms are more common in the summer as compared to the spring.

Note that ringworm is not due to worms and is caused by a fungal infection.  It  gets its' name based on an appearance that looks like a worm.  Infected cats can spread worms to humans through the feces.  Worm eggs are resilient and can be found outdoors such as in parks and indoors if an infected cat lives in the home.

Worms that cats can become infested with:

Roundworms in Cats  (toxascaris leonina and toxocara cati, ascarid): This is a common intestinal parasite of cats. Adult roundworms are white or brown in color and are several inches long. You may notice them in your cat’s stool or vomit. Symptoms of roundworms include weight loss and a “potbellied” appearance.

Roundworms in cats can cause disease in both cats and humans (larva migran syndrome).  This type of cat worm is usually seen in kittens, but can occur at any age.  These worms can be transmitted through a queens (kittens mother) milk during the first 2 to 3 weeks of life.  This worm will not only infect the kitten, but can also be shed into the cat's environment.

Cat Worm Picture Roundworm
Cat Worm Picture - Roundworm

Cat Hookworms (ancylostoma tubaeforme and ancylostoma braziliense): These worms get their name from the hook-like mouth parts they use to attach to the wall of the small intestine. If a kitten is infected, they will look healthy initially, and then get severe anemia, which could possibly result in death.   Infections can occur as early as 3 weeks of age. They are considered “tissue feeders,” but also suck blood from the intestinal wall. They can cause disease in cats and humans, especially children.  

These worms exist in all parts of the United States and are passed from mother (queen) to kitten through the milk, by ingesting through the mouth, or even through skin penetration.  Cats will shed this worm and infect the surrounding environment.

cat worm picture hookworm
Cat Worm Picture - Hookworm

Tapeworms (also called dipylidium caninum): Tape worms in catsinclude a head and many segments and are often caused by eating or swallowing flea larvae or small rodents. They cause vomiting and diarrhea.  The worm is comprised of small segments (hence the name), which can break off as it grows inside a cat's intestines and then pass through the body in the feces.  A tapeworm can be from 4 to 24 inches in size.  Tapeworm infections are not considered dangerous.  It is often diagnosed by seeing the worms moving around a cat's anus or in the feces itself.

Cat Worm Picture - Tapeworm
Cat Worm Picture - Tapeworm

Heartworms: These cat heartworms live in the heart or in the arteries going to the lungs. They can cause heart or respiratory failure with the worms being a big problem for cats because of their small heart. While there is medication to treat heartworms in dogs, they are very difficult tothe point that there is no feline heartworm treatment.  The treatment approach is to support the cat as best as possible while the worms complete their life cycle over a 2 to 4 year period.  There is a very high 50% rate of mortality (death).

Symptoms of heartworm feline include salivation, tachycardia (rapid heart rate), shock, dyspnea (labored breathing), hemoptysis (spitting up blood), vomiting and diarrhea, syncope (loss of consciousness), dementia, ataxia (unsteady movements), circling, head tilt, blindness and seizures.

Almost one-third of cats diagnosed with heartworm were housed solely indoors. There are now three drugs with FDA approval for use in cats. Ivermectin is provided in a chewable formulation, milbemycin as a flavored tablet and selamectin comes in a topical formulation.

picture cat heartworm
Picture Cat Worms - Heartworm

Whipworm: This type of worm is not commonly seen in cats. A cat will contract whipworms from drinking water or food that contains worm eggs. Unfortunately there aren't any approved treatment approaches for this type of infection.

Can You See Cat Worms in Their Stool?

While you can see some worms in cat stool, it is more common that you can’t.

Worms Medicine

Many of the common feline worms can be effectively managed by placing cats on a year-round preventive medicine program (medications are called anthelmintics). There are several worm medicines for the many types of cat worms.

Dewormers can be effective.  The following table lists common ingredients and the method of administration.  Check with your veterinarian for the best approach for your cat.

Cat Worm Medicines

Active Ingredient in Cat Worms Medicine

Route of Administration

Types of Worms Treated

Minimum Age and Weight




After 6 Weeks Of Age

Milbemycin Oxime, (do not use in cats with existing heartworm infections)


Ascarid (roundworm)

After 6 weeks of age and over 1.6 lbs.


Oral/See label


After 6 weeks

Pyrantel pamoate/praziquantel

Orail/See label

Ascarid (roundworm)
Flea Tapeworm
Taeniid Tapeworms
Hydatid Tapeworm

After 1 month and over 1.5 lbs in wieght



Ascarid (roundworm)

After 6 weeks of age

How Your Cat Gets Worm Types

Kittens with worms probably inherited them from their mother. Adult cats tend to catch worms either from an insect bite or because they came in contact with the feces of an infected cat. Even if the feces were removed, eggs might remain that cause infection. 

Worm Types That Can Pass From Your Cat to Adults and Children

It is possible for humans to get intestinal worms from your cat. This is common in children where they touch cat feces. Children that crawl on the ground or play in sandboxes can ingest the eggs that result in worms.  The transmission is often through the ingestion (through the mouth) of eggs shed by an infected pet or if they penetrate the skin.

Humans can get roundworms from cats, and less frequently, tapeworms and hookworms.

Other worms such as heartworms do not infect humans.

Signs and symptoms of human worm infection that can pass from cats to adults include problems with the eyes, brain, liver, and lungs.  These in turn cuase issues with the nervous system, eyesite and possible tissue damage.  Cats spread disease less often than dogs.  Another symptoms is skin lesions and inflammation of the intestinal tract (enteritis) which in turn can cause symptoms such as diarrhea.

Hookworms in humans move throughout the skin causing inflammation.(called cutaneous (skin) larva migran. One form of hookworm can penetrate into the tissues and intestines causing damage to those parts of the body.

Worms are often transmitted through outdoor play areas such as sand boxes.  

Preventing worms the pass from cat to adults and children is as simple as making sure your cat is dewormed and uses a prevetative such as a topical.

How to Keep from Getting Worms from Your Cat

Natural Remedies and Cat Worms

Natural remedies to help with cat worms are made from a collection of herbs thought to support digestive health and the immune system. The herbs are safe and might be worth trying if cat worms are a frequent problem. Remedies include:

One product made specifically for cat worms that combines all of these ingredients is Parasite Dr. Capsules which naturally expel internal parasites like Heartworm, Roundworm and Tape Worm in cats. Alert your veterinarian so that he or she can track progress.


Feline Heartworm Disease 2003
Clarke E. Atkins, DVM, DACVIM
Professor of Medicine and Cardiology
North Carolina State University

Total Parasite Control - Piecing the Puzzle Together
M.W. Dryden
College of Veterinary Medicine

Feline Preventive Care Review
K.K. Faunt
Banfield, The Pet Hospital

Center for Disease Control


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