Lungworms in Cats: What Are They, and How Do You Treat Them?

Published May 28, 2024
A cat lays in the grass.

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What Are Lungworms in Cats?

Lungworms in cats are small (less than 1 cm) parasites that infect cats around the world. It’s estimated that up to 50% of cats allowed outside may be infected with lungworms, but this number is much lower in indoor pet cats.

A cat gets infected with lungworms by eating an animal that’s infected with tiny lungworm babies, called larvae.

The larvae then work their way from the cat’s digestive tract to the lungs, where the larvae grow into adult worms (about eight to nine days after infection) and lay eggs (about four weeks after infection).

In the lungs, the lungworm eggs hatch into larvae. The cat coughs up the larvae and swallows them, and then the larvae are passed into the cat’s stool where the life cycle restarts. Adult lungworms live in the lungs for nine months or longer.

The worms cause irritation and disease in the lung tissues, which can lead to no symptoms, mild symptoms, or serious lung issues including pneumonia or trouble breathing, which is a medical emergency.

Lungworms in cats can be tricky to diagnose because the symptoms can look like other diseases such as asthma, heartworm disease, bronchitis, and pneumonia.

Symptoms of Lungworms in Cats

Cats infected with lungworms may seem healthy with no clinical signs. Lungworms in cats can cause a wide range of symptoms, including:

Causes of Lungworms in Cats

Cats get lungworms when lungworm babies (larvae) are eaten.

This can happen when a cat eats a rodent, small bird, frog, toad, snake, lizard, snail, or slug that is infected with the lungworm larvae.

How Veterinarians Diagnose Lungworms in Cats

If your cat has spent time outdoors and is having symptoms including coughing, wheezing, or breathing issues, your veterinarian may suspect that your cat has lungworms.

To diagnose lungworms in cats, your veterinarian may offer tests, including:

  • Physical examination, which will include listening to your cat’s lungs and heart.

  • Microscopic identification of worms from the stool (fecal examination) using a specific method called the Baermann technique (sent to a lab or done by your vet). This is the most accurate way to diagnose lungworms.

  • Chest X-rays (done by your vet). Your vet will screen your cat for abnormal changes in their lungs.

  • If you can see worms in what your cat has coughed up, your veterinarian may want to do a microscopic test to identify the worms (sent to a lab or done by your vet).

Treatment of Lungworms in Cats

Lungworms are treatable with either oral and/or topical medications prescribed by your veterinarian.

Your vet may prescribe one of these treatments for lungworms:

Lungworms may be killed with a single course of treatment, but most cats are treated for two months.

Depending on the severity of your cat’s infection (number of worms) and your cat’s health status (amount of lung damage), your vet may prescribe multiple dosages of an anti-parasitic medication for you to give on a schedule.

For very sick cats with severe breathing problems, veterinarians may need to prescribe additional medications, such as ones that decrease airway swelling (corticosteroids) and ones that help your cat breathe easier (bronchodilators).

It’s important to carefully follow your vet's directions for treatment and to schedule follow-up visits and tests to make sure this treatment is working for your cat's lungworm infection.

Recovery and Management of Lungworms in Cats

Cats that are mildly infected with lungworms can completely recover within a few weeks with anti-parasitic treatment.

If your cat has symptoms, your vet may recommend an immune system supplement such as Imuquin® powder on your cat’s food, and an omega fatty acid supplement to help decrease airway swelling and provide immune system support.

Wrapping medications in Pill Pockets™ can help!

Prevention of Lungworms in Cats

The best prevention for lungworms in kittens and cats is to keep them indoors to stop them from hunting and eating animals infected with worms, to give them monthly parasite prevention year-round for life such as Revolution®, and to have wellness visits with your veterinarian.

Lungworms in Cats FAQs

Can a cat with lungworm be cured?

Yes, most cats infected with lungworm can be cured with prescription anti-parasitic treatment.

Some lungworm infections may even clear up on their own without treatment. Rarely, young kittens, weakened cats, or cats with lowered immune systems (immunocompromised) can’t be cured.

Can an indoor cat get lungworm?

Yes, an indoor cat can get lungworm if they eat an infected rodent, snail, or slug that comes inside the house, but this is unlikely with good pest control.

Outdoor, free-roaming cats who hunt and eat infected rodents, birds, frogs, toads, snakes, lizards, snails, and slugs are at the highest risk of getting lungworms.

Is lungworm in cats contagious to humans?


Aelurostrongylus Abstrusus. Companion Animal Parasite Council.

Ballweber L. Lungworm Infection in Animals. Merck Veterinary Manual. Revised October 2021.

Elsheikha HM, Schnyder M, Traversa D, Di Cesare A, Wright I, Lacher DW. Updates on feline aelurostrongylosis and research priorities for the next decadeParasites & Vectors. 2016;9(1):389.

Lacorcia L, Gasser R, Anderson G, Beveridge I. Comparison of bronchoalveolar lavage fluid examination and other diagnostic techniques with the Baermann technique for detection of naturally occurring Aelurostrongylus abstrusus infection in catsJournal of the American Veterinary Medical Association. 2009;235(1):43­­–49.


Molly Price, DVM


Molly Price, DVM


Dr. Molly Price has practiced small animal medicine for over 20 years and is a graduate of Texas A&M College of Veterinary Medicine. She...

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