Lungworm in Cats

Lungworm in Cats

Lungworm in Cats

As their name suggests, these parasites live in the airways of the cat’s lungs, where they can cause breathing distress. As they don’t always present symptoms, it may not be initially clear that your cat is infected. In fact, studies suggest that up to a third of all cats can be affected by lungworm, although many owners don’t realise it. Kittens are often at greatest risk. Lungworms can lead to pneumonia and death in some cases, but treatment is possible.

A high population of stray or feral cats will increase the likelihood of lungworm infection for other cats in the area. Such cats are more likely to get lungworms through hunting animals hosting the parasite.

What symptoms arise with lungworms in cats ?

They can cause weight loss over a period of time and respiratory signs such as coughing and wheezing. Blood testing is likely to show a raised level of the white blood cells called eosinophils, which are linked with parasitic disorders.

Can lungworms in cats lead to any complications ?

There is a risk, especially with kittens, old cats or those with debilitating illnesses such as feline leukaemia, that the lungworms could cause inflammation of the lung tissue and lead on to pneumonia. Urgent veterinary attention will then be needed.

I have one cat with lungworm. Will this affect our other pet cat?

It presents no direct risk because lungworm can’t spread directly from one cat to another.


Lungworms are found widely around the world and they have a remarkable life cycle. The adult lungworm release their eggs which hatch into tiny larvae in the airways. The larvae are then coughed up from the lungs and swallowed, passing out through the intestinal tract into the environment with the cat’s faeces. At this stage, they must then be consumed by snails or slugs if they are to have any hope of reinfecting a cat. The larvae need time to develop in the invertebrate’s body. The next stage in their life cycle involves the mollusc itself being eaten by another creature, such as a frog, bird or rodent. The larval lungworm will then migrate from the intestinal tract and forms a cyst in the body of this new host.


Finally, only if an infective vertebrate is caught and eaten by a cat will the life cycle be completed. The larval worm then awakens from its dormancy, and travels through the blood system to finish its development in the cat’s lungs.

  • Adult female lungworms are roughly 10mm (2/5in) long, with males being smaller, typically just 7mm (just over 1/sin) in length, and resembling strands of black cotton at this stage.
  • Lungworms tend to be most common in wet areas such as the northwest of Scotland in Britain. These provide the conditions for the slugs and snails on which lungworm larvae depend for their survival.
  • The fact that lungworm larvae depend on two separate stages in their cycle dramatically reduces the risk of transmission.
  • You can control the spread of lungworm by waging war on the snails and slugs which spread the infection. Also, encourage your cat to use a litter tray as a toilet, rather than the garden.