Lungworm in dogs

1st June 2017


UK cats have had a form of lungworm for many years, but a similar parasite has recently started to affect dogs with more severe consequences. The worm has a great Latin name, Angiostrongylus vasorum, and requires either a slug or a snail in its life cycle.


The effects of global warming and animal movements

The worm is common in Europe, and as a result of global warming and the increase in animal movements, the parasite has now established itself here in the UK. The disease initially arrived in the south of England and around London, but it’s now spread to other areas from the South of England, Central Wales and even as far north as the Highlands of Scotland.

An interactive map showing the density of cases can be found at If you type in your postcode, it will show the number of cases reported locally to you. Not all cases are reported to this website but it does give you a feel for the scale of the problem.


Take a look at the Lungworm interactive map


Are all dogs at risk?

All dogs are susceptible, but younger dogs, particularly those with a liking for eating slugs and snails, are at the highest risk of exposure. A dog doesn’t actually have to eat the intermediate host - simply eating grass with a slug trail on it or lapping from a pond which slugs have access to, will allow infection. Even playing with toys, balls and sticks can contaminate and infect a dog.


Are the worms visible?

If the young worms can infect a slug they must, by definition, be very small. Unless you have a microscope and are willing to look through multiple faecal samples, you’ll never see them.


What are the symptoms of the disease?

Once swallowed, the larval stage of the worms make their way to the dog’s heart and the larger blood vessels of the lungs. They produce chemicals that interfere with blood clotting, producing symptoms that can be quite difficult to spot. We would typically find clotting issues and tiredness, rather than obvious ‘worms’.

  • Coughing – this can be dry, harsh and non-productive.
  • Difficulty breathing – look for rapid breathing and increased effort.
  • Reduce appetite – infected animals will feel unwell and have a poor appetite.
  • Weight loss – as a result of the poor appetite and increased effort to breath.
  • Vomiting and diarrhoea – it’s important to check for signs of blood.
  • Lethargy and depression – the disease can be especially tiring especially with exercise.
  • Pale mucous membranes – blood loss can cause gums, lips, tongue and eye colour to be pale.
  • Bleeding – look for bloody faeces, coughing up blood, prolonged bleeding from minor injuries and bruises. You may even notice unusual nose bleeds.
  • Death - if untreated, some cases have proved fatal.


What tests can be run?

Unfortunately, it’s not that easy to diagnose lungworm infections. Adult worms are usually found within blood vessels and are very difficult to see. As the eggs and baby worms are tiny and come out intermittently in the faeces, single faecal samples don’t always identify them either.

Find the evidence - there are other tests we use, such as looking for the parasites DNA in blood samples, chest x-rays and endoscopy, though even these tests aren’t always conclusive.

Contact us if you’re worried that your dog may be showing symptoms such as bleeding more than normal, coughing or persistent lethargy.


Contact us if you are worried


What can be done?

Fortunately, we can treat and prevent most cases very easily with simple, effective parasite control. More advanced cases may need more care and attention but the prognosis, once treatment is established, is generally very good.


Call us for lungworm prevention advice