Canine lungworm is on the rise - but do you need to worry? Find out what lungworm is, why it’s important and how it can be treated and prevented.
Canine lungworm is still relatively uncommon in the UK, but this potentially fatal condition is on the rise. Dogs can easily pick up lungworm by accidentally (or deliberately) consuming slugs and snails, but recognising it can be challenging as the symptoms are often vague. Luckily, effective treatments are available and can be used preventatively in at-risk dogs.
In this article we’ll cover what canine lungworm is, how it’s diagnosed, and most importantly how it can be treated and prevented.
The term lungworm can be used to describe various different worms affecting the lungs of many different species. However, in the UK it’s used almost exclusively to describe one particular worm in dogs: Angiostrongylus vasorum.
Angiostrongylus vasorum is technically a heartworm, as the adult worms live in the heart and major blood vessels - and outside the UK it’s also known as French heartworm. However, the term lungworm is used almost exclusively to describe A. vasorum in the UK, as it most commonly causes respiratory symptoms.
Lungworm is receiving more attention than it once did as cases are steadily rising across the UK. The symptoms of canine lungworm range from mild coughing and lethargy to severe respiratory problems, bleeding and even neurological issues. If the condition is left untreated it can be fatal, so it’s worth being aware of the common signs of lungworm and how you can prevent it.
To understand how dogs get lungworm, it’s helpful to know a little about its life cycle.
Infected dogs and foxes shed lungworm larvae in their faeces. For these larvae to fully develop, they must be ingested by slugs and snails.
This means dogs can’t be infected directly by other dogs - instead, they’re infected by consuming infectious larvae found in slugs, snails and occasionally frogs or other amphibians.
While some dogs will deliberately consume slugs and snails, other dogs will consume them by accident - for example, when grooming themselves, playing with toys outside, or scavenging.
It’s been suggested that, rarely, larvae may also be shed by slugs and snails in their slime, potentially allowing dogs to develop lungworm through more indirect exposure.
Once infective larvae have been ingested, they mature and move through blood vessels to reach the heart. As adults, they live in the heart and major blood vessels, eventually producing eggs. These eggs subsequently reach the lungs and hatch, releasing larvae that then migrate through the lungs before being coughed up, swallowed and shed in the faeces.
The complex life cycle of lungworm means it can cause various symptoms, ranging from a mild cough to severe neurological problems and bleeding.
The signs of lungworm in dogs include:
In severe cases, lungworm can cause secondary conditions including pneumonia and heart failure. If left untreated, lungworm can be fatal.
Diagnosing lungworm can be challenging as the signs are often vague and non-specific. Fortunately, if lungworm is suspected there is a blood test available which can detect most cases.
Your vet may also recommend additional investigations such as assessing your dog’s faeces under a microscope to look for larvae or taking radiographs of the chest to assess the heart and lungs.
Fortunately, lungworm treatment is safe and effective for most dogs and can often be given at home - the products used are some of the same ones frequently prescribed as routine preventative parasite treatments.
In severe cases, however, breathing difficulties and severe illness can be triggered by the dying worms. If your dog has severe symptoms, or you notice them deteriorating after lungworm treatment, it’s important to seek veterinary advice urgently as some dogs require intensive veterinary care during treatment for lungworm.
Lungworm treatments are prescription-only, so if you suspect your dog may be suffering from lungworm you should speak to your vet for further advice. They will be able to discuss your dog’s symptoms and any other potential causes, and can prescribe an appropriate treatment.
The treatment of lungworm in dogs uses the same parasite products that are often used as routine preventative treatments, so you can discuss keeping your dog on routine preventative treatment at the same time.
Lungworm prevention relies both on routine preventative treatments and minimising your dog’s exposure.
The products used for lungworm treatment are the same as those often used for prevention. These include prescription-only spot-ons and tablets which often provide cover against fleas, roundworms and other parasites too. Unfortunately, there are currently no over-the-counter parasite treatments licensed for lungworm prevention in dogs.
Most products that offer effective lungworm prevention must be given monthly, but you should discuss the frequency of dosing with your vet.
Whether or not your dog needs a monthly treatment for lungworm depends on both the likelihood of them consuming slugs and snails and how widespread lungworm is in your local area. Lungworm cases have increased and it is now present across the UK, but some areas are more heavily affected than others. It’s worth discussing your dog’s parasite treatments with your vet at their next routine appointment, or sooner if you have concerns.
Alongside medications, it’s a good idea to try to reduce your dog’s risk of lungworm exposure as much as possible. The biggest risk is from the consumption of slugs and snails, although some evidence suggests that the slime they leave behind may also contribute to infections.
Ways to minimise your dog’s exposure include:
Find out more about routine parasite treatments for dogs.
Wright I. Angiostrongylus vasorum in the UK: a real threat or the bogeyworm? Veterinary Practice. Published April 15, 2024. Accessed October 9, 2024. https://www.veterinary-practice.com/article/angiostrongylus-vasorum-in-the-uk
Angiostrongylus vasorum. Companion Animal Parasite Council. Published March 8, 2021. Accessed October 9, 2024. https://capcvet.org/guidelines/angiostrongylus-vasorum/
Canine Lungworm Angiostrongylus vasorum. European Scientific Counsel Companion Animal Parasites. Accessed October 9, 2024. https://www.esccapuk.org.uk/uploads/news/3qme0gtx/8vtz1dxf_0988_ESCCAP_UK_Diagnostic_Recommendations__Canine_lungworm_v2.pdf
