Lungworm in Dogs

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

Table of Contents

- Overview
- Causes
- Symptoms
- Prevention

What is lungworm?

Lungworm (Angiostrongylus vasorum) is a type of roundworm that affects dogs, but not cats. 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 an emerging disease in the UK, meaning it is becoming more common. There are more cases in certain areas such as the south coast and Greater London area, but 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 dogs but instead by an intermediate host, in this case, slugs and snails. It is from eating infected slugs or snails or their trails that infection may occur. 

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. Treatment is usually given monthly; however, your vet or nurse can advise on the best product and frequency for your pet. 

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


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Page last reviewed: 7th August 2023
Next review due: 7th August 2025

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