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The war on worms: roundworm in cat

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Roundworms are a common parasite in cats and can affect felines of any age. Learn how to spot the symptoms of roundworm – and prevent and treat this parasite –with our comprehensive FAQ.
Roundworm in cats: common questions and answers
Happy cat with kittens
Roundworm in cats: common questions and answers

What are roundworms? 

Roundworms are one of the most common types of worm found in domestic cats; they live in an infected cat’s small intestine. Because roundworms are easily spread and can be contracted in several ways, it’s likely that your cat will become infected with this intestinal parasite at some time in their life.

What do roundworms look like?

Roundworms are white, cylindrical and resemble pieces of spaghetti. The thousands of eggs that they produce are passed in the cat’s faeces, but are tiny and can only be seen under a microscope.

How do cats get roundworms? 

Cats can get roundworms in three different ways:

  1. Roundworm eggs are passed in the faeces of infected cats and can lie dormant in litter trays, sandpits and soil for years. These eggs can then infect other cats if ingested.
  2. Roundworm eggs can be picked up when cats catch and eat infected rodents and birds.
  3. Kittens can become infected with roundworm from their mother via her milk, which is why young kittens often have worms even when they’ve never been outside.



Roundworm larvae can hide in your pet´s tissues in a dormant state, escaping regular worming treatments, and reactivate themselves later. When this happens in

pregnant animals, the reactivated larvae can travel to the mammary glands and infect kittens while they feed on their mother´s milk.


Are some cats more likely to get roundworm than others?

Roundworms 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 environment (e.g. when grooming themselves after walking or lying on contaminated soil/ sand/ litter) and via hunting behaviour if they ingest infected rodents or birds.

What are the symptoms of roundworm infection? 

An adult cat with roundworms will often show no ill effects, although vomiting and diarrhoea can occur on occasion, and you may also see roundworms in your cat’s faeces. Kittens are more at risk and may show a variety of symptoms including vomiting, diarrhoea, slow growth and dull fur.

How can I treat and prevent roundworms in cats? 

If your cat has roundworms, a variety of roundworm treatments are available.

An easy to use spot on treatment is Advocate for cats. Advocate is applied monthly to protect cats against roundworms, hookworms, heartworm, lungworm, fleas and ear mites.

Can I get sick if my cat has roundworms?

Cat roundworms can cause a disease in people called toxocariasis. Although rare, people can accidentally ingest roundworm eggs – for example, if they touch contaminated soil or faeces and do not wash their hands thoroughly afterwards. If this happens, the larvae of the parasite can migrate into our tissues, potentially causing serious disease. In some cases the roundworm larvae end up in the eyes, causing a condition called ocular larva migrans, which can lead to blindness.

What other measures can I take to reduce the risk of roundworm?

Practising good hygiene can help reduce the risks to both pets and people:

  • Pick up your cat’s faeces from the backyard, and regularly clean your cat’s litter box.
  • Wash your hands after cleaning up after your cat.
  • Wash your cat’s bedding regularly, along with any blankets or cushions your cat uses for sleeping or grooming.
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