Everything You Need to Know About Worms in Cats

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Discovering your cat has worms can be shocking and upsetting. Whether they’re external or internal, these parasites can wreak havoc on your cat’s health. But with proper diagnosis and treatment, worms in cats can be effectively treated and eliminated.

The Most Common Types of Worms in Cats

Here’s a list of the most common worms found in felines:

  • Roundworm: These are the most common intestinal parasites found in cats; they’re also visible to the naked eye. Roundworms measure anywhere between three to five inches long and look like spaghetti noodles. They steal nutrients from the food your cat ingests. The worms then produce eggs, which are eliminated through the feces. On occasion, you may be able to see the roundworms moving around in your cat’s poop or vomit.
  • Tapeworm: Tapeworms, another internal parasite, are flat and resemble small grains of rice or sesame seeds. Your cat may contract tapeworms by ingesting a flea infested with tapeworm eggs, either while grooming herself or by eating an infested bird or rodent. The worm will only come to maturity inside the intestine. Pieces of the worm then break off and are expelled through the feces. You may be able to spot them in your cat’s feces or on the fur near the anus, but in some cases they are passed sporadically, making it possible to miss.
  • Hookworm: These small internal parasites get their name from the hook-like teeth they use to attach themselves to the lining of the intestine, where they feed off your cat’s blood. Cats contract hookworms either by ingesting them directly, or from larvae that penetrate their skin. The larvae first make their way to the lungs before settling in the intestines, where they grow into adult worms. Hookworms are the most harmful of the internal parasites, because of the possibility of intestinal bleeding. Fortunately, this type of parasite is less common in cats than other types of worms. Hookworms are not often visible to the naked eye, but because anemia is a primary symptom, you may notice signs such as pale gums/nose, and lack of energy.
  • Heartworm: Heartworms are potentially deadly parasites that infest the heart, blood vessels and lungs. They’re transmitted through the bite of infected mosquitos. Unfortunately there is no cure for heartworm in cats, so monthly preventatives are the only form of protection.
  • Lungworm: Lungworms are contracted when a cat drinks contaminated water or hunts and consumes birds or rodents infested with lungworm larvae. Once the larvae make their way through your cat’s intestines, they travel to the lungs where they develop into adult worms and lay their eggs. Lungworms are expelled either by being coughed up or passed through your cat’s feces. Lungworms often go undiagnosed because the symptoms—in the form of respiratory problems—are similar to those caused by other conditions like bronchitis or pneumonia. Fortunately, lungworm is relatively uncommon.

You may also have heard of ringworm. Despite its name, ringworm is not actually a worm. It’s a fungal disease that affects the skin and hair of a cat.

In this remainder of this article, we’ll mostly focus on intestinal worms: roundworms, tapeworms and hookworms.

What are the Signs and Symptoms of Worms in Cats?

Both indoor and outdoor cats, old and young, can contract worms. Adults can contract worms from contaminated feces, fleas, or rodents, while younger kittens can be exposed to worms through nursing.

The following symptoms are signs that your cat may be infested:

  • Visible presence: For many cat owners, the first sign will be a visible presence of worms. You may see whole worms, parts of worms or worm eggs in your pet’s stool or vomit. Worms or eggs can also sometimes migrate to a cat’s anus, getting stuck in the fur.
  • Change in coat: If your cat is infested with a parasite, their fur may appear dull, rumpled or clumped due to lack of nutrients or dehydration.
  • Change in color of gums: The gums of a healthy cat should be nice and pink, but if they appear pale or white, your cat may be experiencing anemia, due to the worms.
  • Vomiting: Vomiting is a common occurrence in cats, but if it’s happening more frequently than usual, worms could be the culprit.
  • Change in stool / bowel movements: Dark, tarry stool indicates the presence of blood, potentially from hookworms. Worms in the gut can also cause diarrhea.
  • Increased appetite despite weight loss: As the worms deprive your cat of vital nutrients, they need to take in more food in order to try to maintain their body condition.

If you notice any of the above signs, it’s important to have your cat examined by your vet immediately.

Diagnosing and Treating Worms in Cats

While some worms can be seen by the naked eye, others must be diagnosed with fecal testing. Your veterinarian will ask you to bring in a stool sample, which will be placed in a solution that allows the parasite eggs to separate from the feces and float to the top.

Next, a drop of the sample is placed on a slide and examined under a microscope to determine the exact type of worm infesting your cat. A physical exam, along with blood work, may also be carried out to get a complete picture of your cat’s health.

Because the lifecycle of each parasite is different, it’s important to know exactly the type of worm infesting your cat. This will determine medication, treatment, and follow-up care. After treatment, your cat will likely need another fecal exam to ensure the worms have been wiped out.

Thankfully, most intestinal worms in cats are easily resolved with either a single dose of dewormer or a short course of deworming medication that your vet can prescribe and administer. Certain worms (including hookworms and lungworms) can be more stubborn to resolve, resulting in slightly longer treatment courses of intestinal dewormers.

Preventing an Infestation (or Re-infestation) of Worms in Cats

Once your cat has been treated for worms, it’s important to continue to be proactive about keeping her safe. Adhering to a strict year-round flea prevention regimen can help reduce the risk of tapeworm infection, since fleas carry worms.

Equally, if your cats are avid hunters and especially if they spend time both indoors and outdoors, preventative deworming every 3 months can help eliminate any intestinal worms before they can become a large burden for your pet. Finally, pay attention to your cat’s litter box, keeping it fresh and clean on a daily basis.

There are some worms that can be harmful to humans. In order to protect yourself, along with your cat and any other pets, clean up cat feces immediately, wash your hands, and if possible, wear gloves whenever cleaning the litter box.


There are many different types of worms that can infest cats, so be aware of the signs and symptoms. Immediate treatment will not only help prevent the infestation in your cat from becoming worse, but it will also help protect the other pets (and humans) in your household. Discovering that your cat has worms may be disturbing, but with effective treatment from your vet, your cat will be worm-free before you know it!

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