The war on worms: Roundworm in cats

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Roundworms are a common parasite of cats and can affect cats of any age, so it’s important to know what you’re up against.

Most cats will be affected by roundworm at some point in their lives; learn what you can do to help protect your cat and how to recognise the signs of roundworms in your cat.


Roundworms are one of the most common types of worm found in domestic cats; they live in your cat’s small intestine. These white, cylindrical worms can affect any breed of cat, at any age, though they are most common in kittens. Kittens are often infected with roundworms when they suckle their mother’s milk, and adult cats can become infected in a variety of ways, including by accidentally ingesting roundworm eggs from the soil and via hunting behaviour if they ingest infected rodents, birds or by eating raw or undercooked meat.

Cats with roundworms often don’t show any obvious signs of discomfort, though symptoms can occur in some cats. Importantly though, cat roundworms can also cause a disease in people called toxocariasis. If people accidentally eat roundworm eggs, the larvae of the parasite can migrate into our tissues, potentially causing serious disease. In some cases the larvae end up in the eyes, causing a condition called ocular larva migrans, which can lead to blindness. This condition is very rare, but obviously extremely serious when it does occur, and is one of the reasons that regularly worming our pets is so crucial.   

How do cats get roundworms?

Cats can get roundworm in three different ways. Roundworm eggs are passed out in the poo of infected cats and can lay dormant in many different places, including soil, sand pits and litter trays, and can infect other cats if they ingest them. This is why it’s so important to pick up and safely dispose of any cat poo in your garden, and to clean out your cat’s litter tray regularly. Secondly, roundworm eggs can also be picked up when cats catch and eat infected rodents and birds. Lastly, kittens can become infected with roundworm from their mother via her milk, which explains why young kittens often have worms even when they’ve never been outside.

Signs of roundworms in cats

An adult cat with roundworms will often show no ill effects at all, though vomiting and diarrhoea can occur on occasion. Kittens are more at risk, and may show a variety of symptoms including vomiting, diarrhoea, slow growth and fur that lacks its usual shine.

How do you treat roundworms in cats?

Worming treatments are available that can kill this common parasite. It’s especially important to worm young kittens as they are likely to be exposed to roundworms from their mother’s milk. A variety of roundworm treatments are available. It´s recommended that adult cats need worming at least four times a year.

Other measures to reduce the risks

Good hygiene is also important to help reduce the risk both to other pets and to ourselves. Wash your hands after cleaning out litter trays, and make sure all your pets are treated regularly for fleas and worms. Wash your cat’s bedding regularly, along with any blankets or cushions your cat uses for sleeping or grooming.

Did you know…

Roundworm larvae can hide out in your pet´s tissues in a dormant state, re-activating themselves at a later date. When this happens in pregnant animals, the re-activated larvae can travel to the mammary glands and infect puppies and kittens while they feed on their mother´s milk.

Speak to your vet to find out more on effective worming treatments.

cat roundworms

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