Lungworm in Dogs

Written by Shula Berg BVSc CertAVP(GSAS) GPAdvCert(SASTS) MRCVS
Clinically reviewed by Elizabeth McLennan-Green BVM&S CertAVP(SAM) MRCVS

- Overview
- Causes
- Symptoms
- Prevention

What is lungworm?

Lungworm is a type of roundworm that affects dogs, but not cats. Its proper name is Angiostrongylus vasorum. Unlike other roundworms, lungworm does not live in the intestines. Lungworms live in the heart and surrounding blood vessels, and can cause serious illness and even death.

Lungworm is considered to be an emerging disease in the UK, meaning it is becoming increasingly common. There are more cases in certain areas of the country, such as the South coast and Greater London area, but it is widely accepted that lungworm infection can now occur anywhere.

How do dogs catch lungworm?

All dogs can become infected with lungworm, but it is seen more often in young dogs and puppies. Lungworm infections are not passed directly between animals. Instead the eggs must pass through an intermediate host (another animal that can pass the tapeworm without being ill). For lungworm, the intermediate hosts are slugs and snails.

Although most dogs won’t choose to eat slugs and snails, they can swallow them accidentally when they forage through undergrowth, eat grass or drink from puddles. Dogs can also be infected by slime trails on outdoor food, water bowls or even toys.

What are the symptoms?

Lungworm infection can cause very vague symptoms that often look like other conditions. For this reason it can be tricky to diagnose. Some animals will be unwell for months or even years as symptoms become chronic. Symptoms can include:

Coughing
Breathing difficulties
Weight loss
Poor blood clotting (sometimes seen as bleeding)
Lethargy
Vomiting and diarrhoea
Poor appetite
Seizures
Stomach or back pain

Diagnosis can be challenging and often requires several different tests, including testing for worm eggs in stool samples and taking blood tests. In some cases, we never manage to prove the presence of lungworm. The good news is that lungworm infection can usually be treated, especially if caught early.

How do we prevent lungworm?

Lungworm can be prevented by regular worming of dogs, using an appropriate product. Your vet or nurse can advise on the best product and frequency for your pet, based on their personal risk profile.

Full worming treatment is included in membership of The Healthy Pet Club.

Disclaimer

Please note that the content made available on this webpage is for general information purposes only. Whilst we try to ensure that at the time of writing all material is up to date and reflects industry standards, we make no representation, warranties or guarantees that the information made available is up to date, accurate or complete. Any reliance placed by yourselves is done so at your own risk.

Page last reviewed: 2^nd September 2025
Next review due: 2^nd September 2027