Protecting your cat from internal parasites

Like most animals, cats can become infected with internal parasites. These parasites come from a number of sources, such as fleas, the environment, or rodents that your cat kills and eats, so you can never be sure that your cat is parasite-free. However, your cat’s lifestyle will affect its risk of having parasites, as well as which parasites it is likely to have. That’s why it is important to get worming advice from a vet who can tailor the frequency and type of deworming treatment to your individual cat.

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How to tell if your cat has parasites

Cats that have parasites usually show no signs of the infection. However, some cats show:

  • Weight loss
  • Vomiting
  • Diarrhoea
  • Irritation round the anus
  • Infected kittens may fail to put on weight or grow normally.

Common parasites that live in cats’ intestines


  • The eggs of these long, round worms are passed in the cat’s faeces; the eggs may remain infectious for years
  • Cats may become infected by ingesting the eggs, or by eating another infected animal (e.g. a rodent)
  • Kittens can become infected through their mother’s milk.


  • These flat, tape-like worms pass segments full of eggs in the cat’s faeces; the segments look like small rice grains
  • The eggs then infect a flea or a rodent
  • If the cat eats the rodent, or is bitten by the flea, it is likely to become infected
  • If your cat hunts or has fleas, you should assume it has tapeworms.


  • These short, thin worms pass eggs in the cat’s faeces
  • The eggs develop into larvae in the environment and can then re-infect the cat if they are eaten, by migrating through the cat’s skin, or by infecting another animal (e.g. a rodent) that is then eaten by the cat.

Preventing parasite infection in cats

  • You can reduce the risk of parasitism in your cat by:
  • Preventing/treating promptly any flea infestations
  • Discouraging or preventing your cat from hunting
  • Cleaning out the litterbox daily
  • Taking veterinary advice about prevention, diagnosis and treatment of parasite infections
    • This applies to all cats; note that your vet will have specific recommendations for young kittens (those 2–3 weeks old) and pregnant cats.

Preventing parasite infection in humans

Some cat parasites can infect people but with sensible precautions the risk is low. The strategies listed above will help to decrease the risk. In addition, you should:

  • Dispose of cat faeces appropriately
  • Wash your hands after handling litterbox material
  • Prevent your cat from using sandpits and children’s play areas as a toilet
  • Ensure your children wash their hands after playing outdoors
  • Not handle cat litter if you are pregnant.