Worming your cat: how often, with what and why even if they never go out
"My cat never goes out, so they do not need worming" is an oft-repeated line that is only half true. How often depends on how your cat lives, and a kitten, a flat cat on dry food and a country cat that hunts mice are not the same. Here is a sensible schedule for each.
Internal and external: two different things
Internal parasites live mainly in the gut: roundworms such as Toxocara cati, hookworms, tapeworms such as Dipylidium or Taenia, and protozoa such as Giardia or coccidia. There are other, less common ones that lodge in the lungs or heart. External parasites live on the skin or coat: fleas, ticks, ear and skin mites, and mosquitoes and sandflies, which bite and transmit diseases. Some products cover only internal parasites, some only external, and some both. What matters is knowing what each one covers, because a "complete" product of one type may not cover parasites your cat is actually at risk of picking up.
Kittens: more often
Kittens are often infected with Toxocara through their mother's milk, so almost all of them are born or raised with roundworms. The recommendations of ESCCAP, the European council of experts on companion animal parasites, are to worm kittens against roundworms from three weeks of age, every two weeks until two weeks after weaning, and then monthly until six months. The nursing mother should be treated too. Always use products suitable for the kitten's age and weight: not all are suitable for small kittens. If you adopt a kitten, take a stool sample to the first visit even if you are told they have been wormed.
Adult indoor cat
A cat that always lives indoors, eats dry food or cooked commercial food and does not hunt has a low risk of internal parasites, but not zero: they can be infected by eggs brought in on shoes, by flies or cockroaches they eat, or by fleas, which pass on tapeworm. For these cats, ESCCAP suggests worming at least once or twice a year against internal parasites, or doing regular faecal tests instead. For fleas, protection is adjusted to the household risk: if they live with a dog that goes out, or there is a history of fleas, continuous protection is advisable.
A cat that goes out or hunts
A cat with outdoor access that hunts mice, birds, lizards or snails, or that lives with young children or immunocompromised people, has a higher risk and also more impact if infected. For these cats, ESCCAP recommends worming against roundworms at least four times a year, and in many cases monthly, especially hunters, which can also pick up tapeworms from rodents. Cats on a raw diet also have a higher risk of parasites and other infections. For fleas and ticks, continuous protection all year round, or at least in the warm months in colder areas.
Parasites you cannot see: lungs and heart
There are lungworms, such as Aelurostrongylus abstrusus, which cats pick up by hunting snails, slugs, lizards, frogs or birds that carry them, and which cause coughing and breathing difficulty sometimes mistaken for asthma. And there is heartworm, Dirofilaria immitis, transmitted by mosquitoes, which in cats is less common than in dogs but potentially serious and hard to diagnose, in endemic areas such as the Canary Islands and some humid parts of mainland Spain. For cats that go out and live in risk areas, the vet may recommend a product that also covers these parasites. Ask about the risk where you live.
What about toxoplasmosis?
Toxoplasma gondii is a parasite that a cat may shed in its faeces for a few weeks in its life, almost always the first time it is infected, usually by hunting or eating raw meat. Routine worming does not prevent it. For people, including pregnant women, the main route of infection in Spain is undercooked meat and poorly washed vegetables, rather than the cat. Even so, it is wise to scoop the litter tray daily, because the eggs need a day or more to become infective, wear gloves or wash your hands afterwards, and not feed the cat raw meat. We explain it in detail in the article on toxoplasmosis and pregnancy.
Tablet, spot-on or paste
Wormers come as tablets, pastes and spot-ons applied to the skin at the back of the neck, some of which combine external protection. For many cats, the combined spot-on is the simplest option because it avoids the tablet battle. If you use tablets, you can hide them in a treat or use the technique we explain in the article on how to give a cat a pill. Always match the product to the cat's current weight, weighing them first, and do not use dog products: some are toxic to cats. Note the dates on a calendar or in an app so you do not forget.
Faecal tests: the smart alternative
Instead of worming blindly, low-risk cats can have regular faecal tests, for example twice a year, and be treated only if positive. It is a way to avoid unnecessary treatments and to detect parasites the usual wormer does not cover, such as Giardia or some protozoa. Collect faeces from two or three different days in a clean pot and keep them in the fridge. In cats with chronic diarrhoea, testing is essential before switching products.
What it costs per year
As a guide in Spain in 2026: a worming tablet for cats costs 5 to 15 € per dose; a combined internal and external spot-on, 12 to 25 € per month of protection; a faecal test, 25 to 50 €. A low-risk indoor cat can cost 20 to 60 € a year in parasite control; a cat that goes out or hunts, with full year-round protection, 120 to 250 €. Ask your clinic about annual health plans, which usually include vaccinations, check-ups and parasite treatments at a fixed price.
Kittens are wormed every two weeks from three weeks old and then monthly until six months. A low-risk indoor cat, at least once or twice a year or with faecal tests; one that goes out or hunts, four times a year or more. Always cat products, never dog ones.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.