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dog lungworm

Lungworm infection in dogs

Lungworm (Angiostrongylus vasorum) is a life-threatening disease of dogs. The number of cases in the UK over the last few years seems to be rising. Our vet explains what signs you should look out for and ways in which you can treat lungworm.

This article was written by a FirstVet vet


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This article covers:

  • How are dogs infected with lungworm?
  • Why are the number of lungworm cases rising?
  • What are the signs of a lungworm infection?
  • How is lungworm diagnosed?
  • How is lungworm treated?
  • How is lungworm prevented?
  • How are dogs infected with lungworm?

Dogs become infected with lungworm by eating infected slugs, snails or even their slime trails carrying lungworm larvae. Ingestion of snails and slugs may be purposeful by inquisitive young dogs or by accident for example, when a slug or snail is sitting on grass or a favourite toy! Once ingested the larvae larvae travel through the intestines and into the lungs via blood vessels where they mature to adults and lay eggs. The eggs hatch producing larvae, which are then coughed up, swallowed and released into the environment in the dog’s faeces. The larvae are then ingested by more snails or slugs and the cycle continues.

Why are the number of lungworm cases rising?

As yet, it is unclear why there has been a recent increase in case numbers. The worm is known to favour warmer , wetter temperatures and a change in climate could be one reason. Foxes can also be infected and act as a reservoir, spreading worm larvae in their faeces. The increase in urban fox populations may be another reason why vets are seeing more cases. It may also be that an increase in awareness and better testing means that more dogs are being tested resulting in more positive results.

What are the signs of a lungworm infection?

Lungworm infection can present itself in many different ways. Equally, some infected dogs may appear totally healthy, but will still be shedding lungworm larvae into the environment and contributing to the spread of infections. The wide range of signs can easily be confused with other diseases, so discussing these with your vet is important.

Common signs include:

  • Persistent coughing

  • Persistent bleeding from insignificant wounds

  • Vomiting and blood in the vomit

  • Bruising or blood spots on the gums

  • Reluctance to exercise, weakness, collapse

  • Depression

  • Weight loss

  • Seizures

  • Paralysis

How is a lungworm infection diagnosed?

Lungworm infections can be detected by measuring antibodies in the blood or by looking for worm larvae in the faeces.

How is lungworm treated?

A mild lungworm infection can usually be treated with anti-parasite medication to kill the worms and larvae. However a heavy worm burden must be treated more carefully as killing all the worms at the same time can lead to complications. In this case additional anti-inflammatory medication may also be used. The type of drug used and the duration of treatment will depend on how severe the infection is.

Dogs suffering from complications of a lungworm infection such as, poor blood clotting/ bleeding, poor breathing and oxygenation or seizures will require hospitalisation and further supportive treatment.

Please note that the drugs that kill lungworm are only available in prescription veterinary products. Products bought in pet shops or online without a veterinary prescription are unlikely to treat lungworm.

How is lungworm prevented?

The risk of lungworm can be reduced by:

  • Using a worming treatment that is effective against lungworm at regular intervals in the year depending on how ‘at-risk’ your dog is. Your dog will be more at risk if he or she is prone to eating grass or picking up slugs/snails. Speak to your vet about the prevalence of lung worm in your area

  • Picking up toys or water bowls left outside and cleaning thoroughly

  • Preventing your dogs from exploring areas with a high number of slugs and snails where possible


When should I see a vet?

  • Contact your vet if you are worried about any of the signs described above
  • Contact your vet as an emergency if you notice persistently bleeding wounds, blood spots on the gums, shortness of breath, severe lethargy, seizures

Further reading

Worming your dog - Q&A
Why does my dog eat grass and vomit?

Still worried?

If you would like further advice on anything you have read in this article you can book a video appointment to have a chat with one of our FirstVet vets for advice, treatment, and if necessary, referral to your local vet.

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