How do cats get roundworms?

posted: 05/15/12
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Roundworms are pesky little parasites.
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Most cats will get worms -- nasty parasites that invade their systems -- at some point in their lives. Outdoor cats that hunt rodents can get roundworm from eating their prey; kittens usually get it via milk from their infected mothers. Even indoor cats may ingest an infected fly that finds its way into your home. That's scary, because people can get it too. Luckily, treating feline roundworm is fairly easy. Guarding against it, with the right prevention and a clean environment, will keep your cat and its owner in a roundworm-free zone.

What is Roundworm?

Roundworms are the most common form of parasites found in cats. They're large, averaging 3 to 6 inches (7 to 15 centimeters) in length, and round, as the name suggests. They infest a cat's intestines, hatch in its intestinal tract, and eventually migrate to the liver, bloodstream and lungs. Significant numbers of roundworms can be fatal for kittens.

Scientifically known as Toxacara cati, feline roundworm is contracted when cats ingest roundworm eggs containing larvae. Eggs reside in hosts, such as rodents, birds, cockroaches or earthworms eaten by outdoor cats. They can also live in the feces of infected cats, or in soil. Roundworm is usually transmitted to kittens in milk from a mother whose mammary glands are infected with larvae.

While outdoor cats are most likely to get roundworm, indoor cats aren't immune. They may eat an infected insect that introduces larvae into their systems. And an infected cat's feces can leave eggs in a litter box, potentially infecting other cats or humans.

Symptoms of Roundworm

Feline roundworm is easily recognizable. You'll see visible spaghetti-like strings in the cat's stool or vomit. Even if no intact roundworms appear, symptoms are distinctive. Kittens with roundworm look pot-bellied, and their stomachs feel hard. Yet, because roundworms deplete their food intake, infected kittens are actually malnourished and the rest of their bodies look thin.

Other signs of roundworm include vomiting, diarrhea, weight loss, a poor appetite and a dull coat. Although kittens are most at risk, untreated roundworms can multiply and create an intestinal blockage in any cat, causing severe constipation.

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Yes, people can get roundworm from cats. If you touch soil contaminated by roundworms through animal feces, or handle an infected cat's stool, you can ingest roundworms. As with cats, roundworm larvae can invade human intestines. They can enter the bloodstream, migrate to vital organs, and also enter the eyes. In extreme cases, roundworm larvae have been known to cause permanent damage to the eyes of children who have come in contact with infected cat feces, and then put their hands into their mouths.


Once you know that your kitten or cat has roundworm -- your vet can test a fecal sample to confirm it -- treatment is simple. Cats are given an oral deworming medication, called an anthelmintic. Your vet can prescribe the right dewormer, preferred when treating kittens, but over-the-counter versions are also available. The dewormer forces adult roundworms out of the cat's intestines, and into the stool.

Your cat will need more than one deworming session to be fully cured. Deworm your pet at least twice, possibly three times, leaving two to three weeks between each dose.


To keep roundworm away, be vigilant in cleaning your cat's living area, disposing of litter box contents frequently. If your cat goes outdoors, hunting small animals that can carry roundworm, or walking on contaminated soil, consider keeping him indoors.

Some monthly flea and heartworm medications also help fight roundworm. Kittens should receive deworming medication on a regular basis throughout their first year to keep their intestines clear. Your vet can prescribe the best preventative choice to keep your cat healthy and roundworm-free.

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