Worms in cats

Worms are parasites that live inside a cat’s body. 25-75% of UK cats have worms. Most cats will pick up worms at some point in their lives, but untreated cats, kittens and cats who hunt are most at risk.

Different types of worms live in different parts of the body. They cause health problems which range from mild to life-threatening and the illnesses they cause depend on their location. You can protect your cat against the risk of worms with regular preventive treatment using an effective wormer. Different wormers may be required for different types of worms.



How do I know if my cat has worms?

Two types of worms are most common in cats – roundworms and tapeworms. Lungworms, hookworms and whipworms also occur in the UK, but are uncommon in cats.


Roundworms and tapeworms

They live in your cat’s intestines. They might not cause any symptoms at all, so you don’t always know if your cat has worms.

Roundworms can grow up to 15 cm long in cats. And even small types of tapeworms reach 50cm.

Tapeworms are like long ribbons made up of lots of tiny individual segments. Each segment contains between 30.000 and 1.000.000 eggs. They break off from the adult worm and pass out through your cat’s bottom in poo.



Symptoms of worms in cats

Evidence your cat has intestinal worms includes:

  • Excessive grooming under their tail, possibly causing hair loss.
  • Spaghetti-like roundworms in poo or vomit
  • Small white things in poo that look like grains of rice are tapeworm segments
  • Tapeworm segments may also be stuck in the hair around your cat’s bottom and tail


Intestinal worms

Intestinal worms steal your cat’s food and stop them gaining or maintaining weight. But they rarely cause severe illness, except in young kittens. Symptoms of worms relate to tummy upsets or poor nutrition.

  • Poor body condition and weight loss
  • A dull staring coat
  • Developing a ‘pot belly’
  • Diarrhoea and vomiting, which can be severe in kittens and untreated cats and may contain blood.
  • A cough caused by migrating immature worms. (see later)


Worm Larvae

  • After cats and kittens swallow roundworm larvae, the larvae leave the intestine and migrate through the body to the lungs
  • Maturing larvae are coughed up and swallowed before becoming adult worms inside the cat’s intestines
  • Kittens with a lot of worms may develop breathing problems and pneumonia caused by damage from the migrating larvae
  • Adult worms can completely block or even burst a cat’s intestine, causing life-threatening illness. Small kittens are at greatest risk



They live inside your cat’s lungs or windpipe. You won’t see evidence of these worms in your cat’s poo.

Symptoms include:

  • Chronic coughs lasting weeks to months
  • Runny nose
  • Weakness and low energy
  • Breathing difficulty and pneumonia
  • Poor appetite and weight loss

Aelurostrongylus abstrusus is the most common lungworm in cats in the UK.

Other lungworms are very rare in the UK, but include Capillaria aerophila.



How do cats get worms?

The risk to your cat depends on their age and lifestyle, but even indoor cats get worms.


Intestinal worms

  • Eating soil contaminated with worm eggs from faeces (poo).
  • Grooming – licking up unseen worm eggs on their coat
  • Eating dead wildlife, like rodents or rabbits
  • From an infected mum’s milk


  • Eating fleas that have eaten tapeworm eggs.
  • Eating dead wildlife, like rodents or rabbits

Worm eggs passed in faeces can remain in soil for years and still be present long after the faeces itself has gone. Cats walking on contaminated soil get the eggs on their feet and fur and accidentally eat them when they groom themselves.



  • Eating slugs or snails infected with lungworm larvae
  • Eating rodents, frogs or birds that have eaten infected slugs or snails


Is my family at risk?

Intestinal worms

Humans can get infected with roundworms from cats and dogs. Around 5% of adults in the UK have antibodies to the dog roundworm, Toxocara canis. This means that they have been exposed to the infection at some time in their lives. It’s not so clear how many people are exposed to the cat roundworm, but children playing in sand boxes are at significantly greater risk.

Symptoms of illness are very rare, but are caused by migrating larvae:

  • Vague symptoms include tummy pains, high temperature, itchy rash and coughs or wheezes
  • Specific eye symptoms can develop, including redness, pain and even blindness in one eye.
  • There are around 50-100 eye cases each year due to Toxocara roundworms in the UK

The most common lungworm in cats, Aelurostrongylus, does not affect dogs or humans.



Diagnosis of worms in cats

To find out if your dog has worms, your vet will:

  • ask you lots of questions about their lifestyle and symptoms
  • suggest blood and faecal (poo) tests


Vet treatment

What to do if you think your cat has worms?

Vet treatment for worms in cats

Talk to a vet or vet nurse for expert advice if you think your cat has worms.

  • Only a few wormers treat every stage of the worm lifecycle, so it’s important to choose the right one
  • Worming treatments are available as tablets, liquids, granules, paste or spot-ons
  • Many wormers can be purchased from larger pet supply stores or online retailers
  • Prescription wormers from vets will be stronger and more effective
  • Treat your cat for fleas and treat the house to remove flea eggs and larvae
  • Home remedies don’t work

Flea & Tick Spot-On for Cats

 £6.50   £3.90

Multiwormer for cats



Home treatment

Home treatment for worms in cats

There are no home remedies to reliably treat or prevent cats in dogs.

However, home hygiene is essential to reduce risks of transmission and reinfection if your cat has worms.

  • Clean litter trays regularly and dispose of poo carefully
  • Wash all washable bedding and soft furnishings your cat has laid on or walked over in soapy water at the highest possible temperature



How to prevent worms in cats

Roundworms and Tapeworms

Adult cats

  • Worm adult cats at least 4 times per year
  • Choice of wormer depends on your cat’s age, lifestyle and other health concerns
  • Worm cats who hunt every 6 weeks or as advised by your vet


  • Worm kittens every 2 weeks from  2 to 8 weeks old
  • From 8 weeks, worm growing kittens monthly until 6 months

Pregnant cats

  • Worm pregnant cats regularly and at the same time as their kittens
  • Check with your vet which wormers are safe for pregnant cats

Most wormers can’t kill migrating roundworm larvae in cats’ tissues. Treatment will remove worms from the intestine, but a new worm population replaces these when the maturing larvae complete their journey. This is why worming needs to be repeated regularly.




  • Outdoor cats are most at risk, especially if they hunt, so worm them regularly. A monthly spot-on treatment will give your cat the protection they need
  • Avoid using chemicals to kill slugs and snails. These are poisonous to cats if they eat the chemical or the slug.


When to worry

When to worry about worms in cats

Contact your nearest vet if your cat:

  • Is collapsed or unresponsive
  • Is weak and struggling to breathe


Joii can help with:

  • Choosing the right wormer for your cats
  • Understanding risks of worms
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