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Roundworm Infection in Cats: How to Keep Your Cat and Family Safe

Adorable kittens and cats can sometimes carry something much less adorable — roundworms!

Roundworms, also known as ascarids, are parasites that live in the intestines and are very common in kittens. Some show symptoms and some don’t.

The good news is treating roundworms is normally easy. But, it isn’t something you want to delay. Read below to learn why.

What Are Roundworms — And Why Should Pet Parents Care?

The scientific names for the types of roundworm that infect cats is toxocara cati or toxascaris leonina. Roundworms are one of the most common intestinal parasites in cats (others include tapeworm and hookworm). In fact, most cats are infected at some point during their life, usually as young kittens.

These worms, which can grow to 3-6 inches in length, don’t tend to harm healthy adult cats. Young kittens, older seniors, or immune-compromised cats are more at risk, though.

Left untreated, severe roundworm infestations can have serious, life-threatening health consequences for kittens. Plus, the worms can affect humans.


Roundworm Infestations in Humans

Human infections mostly come from soil or sandboxes contaminated with feces from infected animals, but you could also acquire them from an infected cat in your home.

Not surprisingly, children are especially at risk because they’re more likely to put dirty fingers in their mouths. And, unfortunately, roundworms tend to affect children more severely than adults.

Since humans aren’t a natural host for this species of worm, the misguided worms can migrate to various organs in the body, including the eyes (ocular larval migrans) and liver (visceral larval migrans), which can lead to liver problems or blindness.

How Do Cats Get Roundworms?

Ingesting worm eggs

When eggs or larval (young) worms are ingested, they don’t stay in the digestive tract. Instead, the young worms migrate through a cat’s muscles, liver, and lungs. If there are a lot of worms present, this migration can cause serious inflammation or pneumonia.

When worms exist in a cat's lungs, they cough them up and then swallow them, which allows the worms to set up permanent camp in a cat’s intestines. 

Adult worms reproduce and their eggs are released into a cat’s stool. These eggs can infect other cats (and humans) if swallowed.


This is the most common cause of kitten roundworms. During migration, a few worms never make it back to the intestines. Instead, they stay behind and form cysts in the organs they migrated through, especially the liver. These worm-cysts remain dormant for a while, but may reactivate and migrate to the mammary glands during pregnancy. After the kittens are born and start nursing, these worms can infect the kittens via their mother’s milk.


Roundworm eggs can also be found in the tissues of accidental hosts (animals that aren’t ideal hosts for these worms) like mice, birds, or insects. When a cat eats these prey species, they can get a roundworm infestation.

Symptoms of Roundworm Infection in Cats

Cats may or may not show symptoms of a roundworm infestation. If your cat is showing symptoms, you may notice: 

  • Vomiting or diarrhea
  • Worms in stool or vomit (the worms look like pieces of spaghetti)
  • Decreased appetite
  • Pot-bellied appearance
  • Abdominal pain
  • Poor growth
  • Weight loss
  • Dull hair coat
  • Coughing

Symptoms vary from cat to cat or kitten to kitten. That’s why it’s so important to follow your vet’s parasite preventative recommendations.

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How Do I Know If My Cat Has Roundworms?

The most common test for roundworms is a fecal flotation performed by your vet.

A small amount of your cat's stool is mixed with a solution that causes eggs to float to the top, where they can then be picked up and examined on a microscope slide. The eggs are microscopic, so you won’t notice them at home.

In addition to identifying the presence of roundworms, fecal exams spot eggs of many other worm species and other microscopic parasites. So, it’s an important part of your kitten’s health checks.

It’s important to note, though, that false negatives are possible.

Sometimes, cats are infected with young worms, which aren’t yet releasing eggs that can be detected on a test.

But because roundworms are very common in kittens and false negatives can occur, your vet may still recommend treatment.

Cat Roundworm Treatment

Fortunately, treatment for roundworms is simple, effective, safe, and inexpensive — so, there’s no reason to put off getting your cat checked!

Roundworms do have a complex life cycle, though, so, to ensure roundworm larvae and adult roundworms are eliminated, your vet will treat your pet each time they’re due for a checkup. And, if needed, your vet will provide you with additional at-home treatments. 

If your cat gets infected and you have multiple pets in your household, your vet may recommend dewormer treatments for them, too. Cats that share litter boxes with an infected kitten are especially at risk. Dogs are less at risk, since only one roundworm species can affect them (though this species is less common in kittens).


Preventing Roundworms

  • Deworm your kitten or cat as recommended by your veterinarian — usually, they’ll suggest deworming medication at each kitten visit when they receive vaccines.
    • Your vet will also guide you on routine parasite prevention, like a heartworm preventative, which also prevents roundworm infections, for adults once your kitten grows up.
    • If you have a pregnant cat or a recently-born litter of kittens, call your vet right away to ask about deworming.
  • Keep your cat indoors. Going outside increases the risk of parasite exposure.
  • Teach children good hygiene habits, and instruct them to wash their hands after playing with pets or playing in potentially contaminated environments like soil or sand.
  • Clean your cat's litter box at least once per day, and wash your hands after handling the box. If your cat ever does get roundworms, frequent litter box cleaning can remove roundworm eggs before they develop and become infective.

Following these tips will go a long way toward keeping your cat healthy and parasite-free. So, you can spend less time worrying about squirmy parasites and more time cuddling with your fluffy friend! 


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