Think your cat has worms? Find out how to tell for sure and how to treat them is she does.

The bad news: Intestinal worms in cats are very common. The good news: They're relatively easy to treat, and most cats make a full recovery. Plus, there are simple steps you can take to prevent worms in cats and help protect your pet from these parasites.

Which Intestinal Worms Infect Cats?

There are several types of intestinal worms that can infect cats, each with its own set of unique features, says Jessica Nichols, DVM, chief veterinary officer of Spay and Neuter Kansas City in Kansas City, Mo. Here are some of the most common parasites seen in cats:

Roundworms. Roundworms (also called ascarids) are long, brown round worms that look like cooked spaghetti, Nichols says. She adds that they're the most common intestinal parasite in kittens, and kittens are infected more often than adults. 

Tapeworms. Tapeworms are long, white, flat, segmented parasites with hook-like mouth parts that they use to attach themselves to the intestinal walls of cats. Segments of adult tapeworms (called proglottids) will break off and end up in the infected cat's poop. "These proglottids look like grains of rice that move, and they are commonly seen in the poop or around the rear end of infected cats," Nichols says. "They eventually break open and release tapeworm eggs into the environment." 

Hookworms. Nichols says that hookworms are less common in cats than roundworms and tapeworms, which is good because they're particularly nasty parasites. "Unlike other worms that eat food and drink materials floating around the cat's intestines, hookworms hook their teeth into the small intestines and suck blood," she says. 

Whipworms. These can infect the intestines of cats, but according to the Companion Animal Parasite Council, this rarely happens in North America. Feline whipworms are more common in tropical regions. 

Illustration of Roundworm, Tapeworm, Hookworm, and Whipworm
Credit: Eric Jeon

You may be wondering about another type of worm that can infect cats, called heartworms. But unlike the aforementioned type of worms—which live in a cat's intestines—heartworms infect the heart and lungs, causing a condition called heartworm disease. Prevention of heartworms is key, as heartworm disease can be fatal in cats. 

How Do Cats Get Worms?

Worms in cats come from a variety of sources, including mice, fleas, and even their mother's milk. 

Roundworms. Kittens often get roundworms via the milk of an infected mother. Both adult cats and kittens can become infected by eating roundworm eggs from the poop of an infected dog or cat and by consuming roundworm babies from the meat of an infected mouse or other small animal. 

Tapeworms. According to Nichols, cats don't get infected by eating the eggs carried by proglottids. Instead, they get tapeworms by eating either infected fleas or infected small animals like mice, squirrels, and rabbits. 

Hookworms. Hookworms, Nichols says, release their eggs into the feces of an infected animal, which will later hatch into baby hookworms that live in the soil. "Cats then become infected by eating baby hookworms from the soil or by eating an infected rodent, bird, or cockroach," she says. "Baby hookworms are also able to infect cats by burrowing through their skin and traveling to the intestines."

How Can You Tell If Your Cat Has Worms?

The signs and symptoms of worms in cats vary by parasite and can also depend on how many worms the cat has. Often, however, cats with intestinal worms don't show any signs.

Roundworms. Some of the common signs of a roundworm infection include diarrhea, weight loss, low energy, poor haircoat, failure to thrive (meaning the kittens don't grow as they should), and sometimes vomiting. "Kittens will often have a potbelly appearance, and cats that are heavily infected will sometimes have dead worms in their poop or vomit," Nichols says. "Cats with a high number of worms can also suffer from anemia (meaning they don't have enough red blood cells to carry the oxygen their body needs) and blocked intestines." However, she adds that many cats—especially adults—don't show any signs.

Tapeworms. "More often than not, cats with tapeworms don't have any signs," Nichols says. "The most common clinical signs seen by pet owners are the presence of tapeworm segments in their cat's poop or on their cat's rear end." Vomiting, diarrhea, and blocked intestines can occur in cats with a high number of worms. 

Hookworms. According to Nichols, beyond the typical signs of infection such as diarrhea, the blood-sucking parasites can cause severe anemia and even sudden death. Kittens are most at risk. "Another unique feature of hookworms is that they can cause wounds and infections where they burrow into the skin—most commonly on the paws and belly," Nichols says.

How Are Worms in Cats Diagnosed and Treated?

Though intestinal worms can cause serious problems in cats, it's usually a very treatable condition.

Roundworms. "Diagnosis is often done with a fecal float test, which involves using a microscope to look for roundworm eggs in a sample of the cat's poop," Nichols says. And because cats can have roundworms without showing any signs, she recommends using a fecal float test to screen all cats for the parasite once a year. 

Cats infected with roundworms are typically given a deworming medication by mouth, which will immediately start killing the worms, Nichols says. Cats with a high number of roundworms may need multiple doses. Because roundworms are so common in kittens, they're usually given deworming drugs as a precaution. 

Tapeworms. Nichols says that tapeworms are most often diagnosed by either the owner or the veterinarian seeing the tapeworm segments in the cat's poop or around its rear end. Unfortunately, fecal floats aren't as successful at diagnosing tapeworms.

Treatment of tapeworms involves a single dose of a dewormer by mouth, Nichols says. Because fleas are a common route of infection, it's important to treat for fleas as well as the tapeworms. Nichols says she always recommends flea preventatives for her patients that have tapeworm, and she always considers a tapeworm treatment or screening for her patients who have fleas.

Hookworms. Similar to roundworms, a fecal float test can be used to find hookworm eggs in the cat's poop. "Your veterinarian may be prompted to perform the test if they diagnose your cat with anemia or see the skin wounds that are characteristic of hookworms," Nichols says. 

As with the other two types of intestinal worms, treatment involves a deworming medication by mouth. "However," Nichols says, "since hookworms can cause serious problems and reinfection is common, multiple treatments or follow up with prevention is strongly recommended. Drugs used to prevent heartworms and intestinal parasites can be used to both treat and prevent infection." She also recommends performing a second fecal float test after treatment is complete to make sure the hookworms are gone.  

Prevention of Worms in Cats Is Easier Than Treatment

According to Nichols, the best way to prevent intestinal worms is to keep your cat on year-round preventative medications. Many heartworm preventatives can also protect your cat from getting roundworms and hookworms, and flea preventatives play an important role in protecting cats from tapeworms. Your cat's veterinarian can help you find the best options for your pet. Nichols adds that keeping your cat indoors (so he's unable to hunt animals who may be infected) and cleaning his litter box regularly can help guard your cat against intestinal worms. 

Because cats can have intestinal worms without showing any signs, Nichols emphasizes the importance of having your cat screened once a year. This involves bringing in a poop sample from your cat so your veterinarian can perform a fecal float test to look for parasite eggs. "The test is often part of your cat's yearly wellness visit," she says, "and it can identify the presence of roundworms, hookworms, whipworms, and sometimes tapeworms."