It's gradually becoming more common, warns Tony Buckwell

In April and May, with the weather becoming warmer, slugs and snails become much more active which increases the risk of lungworm in dogs. Dogs that eat slugs, snails or frogs, even tiny ones eaten by accident, can catch lungworm from them. Your vet should be able to advise you if a lungworm treatment is necessary in your area and be able to prescribe something appropriate.  (Read more here on worming working dogs.)

(How pill pockets for dogs could make it easier to give tablets.)

How serious is lungworm?

A: Lungworm (Angiostrongylus vasorum) infection is what we call an “emerging” disease. Initially found mainly in the south of the UK, it is gradually becoming more common around the country.


Snails can transmit lungworm to dogs

How is lungworm transmitted?

Lungworm is not passed directly from dog to dog; the worm needs 
a slug or snail host in order to grow and develop, and it is from eating larvae found in infected slugs and snails that dogs become infected. Dogs can, for instance, accidentally eat small infected slugs if they are on a toy left outside. (Read more on why you shouldn’t let your dog drink from puddles.)

The lungworm larvae grow inside the dog, and adult lungworms move through the dog’s body to live in the heart and blood vessels.

Spotting the symptoms of lungworm in dogs

Diagnosing lungworm in dogs can be difficult because symptoms vary, but they can include coughing, breathing problems, a reluctance to exercise and abnormal blood clotting. Lungworm can cause haemorrhages in the lungs, liver, intestine, eyes and spinal cord. Left untreated, lungworm infection can be fatal in severe cases.

If you see slugs and snails in your garden or when out exercising your dog, be extra vigilant. Always pick 
up and safely dispose of your dog’s 
waste and consult your vet if your 
dog becomes unwell. (Read how to make your dog vomit in an emergency.)

David Tomlinson adds:

Thirty years ago, Britain was free of lungworm (also known as hookworm), but this nasty parasite is now firmly established here. The blood-sucking lungworm looks like a roundworm, but it has teeth that it uses to attach or hook itself to the dog’s intestine. It changes the attachment site several times a day, leading to blood loss and causing anaemia and iron deficiency. Slugs and snails are the carriers, infecting foxes or dogs that eat them.

This is one worm that isn’t a threat to humans, but it can be deadly to dogs, though most make a full recovery if given the correct medication. If your dog doesn’t show any interest in eating slugs or snails you don’t have to worry too much.

This article was originally written in 2018 and has been updated.