Guide to Lungworm: what is it, how to spot the signs and protect your dog

By countryfile

Published: Thursday, 13 January 2022 at 12:00 am

Once a rare condition in the UK, Lungworm is now widespread across the country, with cases reported commonly reported in Southern England, Wales Northern England, the Midlands and Scotland.

Fortunately, there are ways to reduce the chance of your dog catching lungworm by taking a couple of simple, but essential precautions before heading outdoors for a walk or to let them play in the garden.

Our expert guide explains what lungworm is, how to spot the signs and what you can do to protect your dog from this potentially deadly parasite.

Head Veterinary Nurse Laura Hawkins and British Veterinary Association (BVA) Past President Gudrun Ravetz explains more about how to spot the signs and treat lungworm.

What is lungworm?

Lungworm is an infection caused by the round worm parasite called Angiostrongylus Vasorum (AV). Slugs and snails carry the lungworm larvae and dogs generally become infected when they play with and consume them. They can also come into contact by eating grass, drinking from puddles, outdoor water bowls or toys that have been left outside in grass as the larvae can be left in the slugs and snails slime trail.

Unlike many diseases, lungworm cannot be passed from dog to dog. The worm needs slugs and snails to act as a host in order to grow and develop. Frogs can also be used as a host.

Incidents of lungworm being diagnosed in dogs were originally more prevalent in the South East and in South Wales, but there have been an increasing number of cases in other parts of the country, including Scotland. However it is still a rare diagnosis.

How is lungworm contracted?

Dogs pick up the AV larvae after eating infected slugs and snails or licking the slime trails left behind. The larvae mature and migrate around the body, ending up in and around the lungs. Worms will then lay eggs which mature into larvae in the dog’s body and are then coughed up by the dog, swallowed and passed in the faeces, which will go on to infect more snails and slugs… And the cycle starts again.

Garden pests

Slugs and snails are hermaphrodites – each individual has both male and female sex organs, so any two individuals can mate and reproduce, and a single individual can even self-fertilise to reproduce. Eggs form in clusters in the soil, beneath leaves, or in other areas where the soil is damp. The eggs can lie dormant in the soil for months and hatch only when conditions are suitable.

_{Slugs and snails can carry lungworm larvae/Credit: Getty}

Agronomist Ryan Hudson says numbers will generally increase during a warm and wet period, such as a wet spring, which can encourage higher adult numbers resulting in more eggs laid for the autumn.

Infected dogs and foxes spread the parasite into the environment by shedding lungworm larvae in their faeces. The disease is then picked up by common garden dwellers including slugs and snails, which, once infected, continue to spread the disease. The parasite can even survive in their slime trails!

Dr Bryony Tolhurst, behavioural ecologist at the University of Brighton, explains: “The lungworm parasite relies on slugs and snails to be transmitted. Dogs can become infected from eating slugs or snails carrying the parasite. Infective larvae can also survive in their slime trails for around two weeks in damp conditions¹, and thus potentially provide another route of exposure to the parasite.”

Foxes

Expanding fox populations are thought to be one of the reasons for its spread, affecting almost one in five foxes across the UK, according to a 2015 study which examines the carcasses of 424 foxes. To date, 2897 cases of lungworm in dogs have been recorded across the country, but as there is no obligation to report the disease, the true number of cases is likely to be much higher, warn experts.