What is lungworm?
Lungworm is a type of parasitic worm, (known as Angiostrongylus
Vasorum) which affects dogs and foxes (who are often implicated in
spreading the disease). Once dogs are infected, adult lungworms
live in their heart and the major blood vessels supplying the
lungs, where they often cause a host of potentially serious
How is lungworm transmitted?
Wet spring months usually mean you'll see a fair few slugs and
snails around and they've all got the potential to carry the
dangerous lungworm parasite. So when your dog rummages through
undergrowth, drinks from puddles, eats grass, or generally sniffs
around outside; they can end up eating these slugs or snails either
accidentally or on purpose. Although slugs and snails can give off
foul-tasting substances that prevent them from being ingested, some
dogs just appear to ignore these warnings. Also any contact with
the slime trail in outdoor food and water bowls, even over toys
left out in the garden, can be enough to cause infection too.
Unlike many diseases, however, lungworm is not actually passed
directly from dog to dog. The worm needs slug and snail hosts in
order to grow and develop, and it's from eating these that
infection may occur, then by the dog passing larvae in its waste.
So the more infected slugs and snails eaten, the more likely
disease is then rapidly spread within dog communities.
What are the effects of lungworm?
After infection, lungworm usually causes progressively worsening
signs of cardiac and respiratory disease (often at 'extremes' of
exercise); as well as causing haemorrhages in lungs, liver,
intestine, eyes, and spinal cord, but also pretty much anywhere in
the body. If left untreated, it can be fatal in severe cases.
How can I tell if my dog is infected with lungworm?
Signs of lungworm disease are vague, and easily confused with
other illnesses, including weight loss, breathing difficulties,
coughing (especially bringing up blood), lethargy, poor blood
clotting/persistent bleeding, general sickness, circling, stomach
and back pain, poor appetite, vomiting, and diarrhoea.
Lungworm is often a chronic disease, lasting months, even years.
However, it will occasionally cause sudden death. Even changes in
behaviour, such as depression, tiring easily, and seizures can
indicate infection, with mild cases often remaining totally
unnoticed by owners.
How is a lungworm infection diagnosed?
An absolute diagnosis of lungworm is difficult and involves a
variety of diagnostic methods, such as blood samples for DNA,
analysis of stool samples for eggs and larvae, chest X-rays, even
Interestingly, not finding worms doesn't mean your dog isn't
infected. Diagnosing lungworm infection is often based on history,
compatible clinical signs and response to treatment.
Which dogs may be prone to becoming infected by lungworm?
Dogs of all ages and breeds are susceptible to lungworm, with
playful, younger dogs (less than two years old), unsurprisingly,
more prone to picking up the parasite. Dogs known to purposely eat
slugs and snails are obviously considered higher risk.
How common is lungworm?
Lungworm is what we call an 'emerging' disease: it's gradually
becoming more common. Until recently it only appeared in select
'hot spots' in the south of the UK, but over the last few years,
it's been successfully identified in various parts of the country.
It's unclear exactly what's caused this spread (and that of other
parasites, including ticks), but increased movement of pets around
the country, and abroad, as well as greater contact between
wildlife and the urban environment are all thought to be very
Not every snail or slug carries the disease and lungworm's
geographical limitations means infection is currently relatively
uncommon, but it does rear its head from time to time; and in
extreme cases, causes death of infected patients, so it is
potentially extremely serious.
What do I do if I think my dog may be infected?
If you're concerned your dog has picked up lungworm, is
displaying signs of the disease, or is at risk from lungworm
infection, then call your vet immediately. Lungworm treatment is
widely available from your vet and extremely easy to administer.
Once diagnosed and treated, most dogs make a full recovery and,
like all diseases, the key to successful treatment is taking action
Killing lungworm is relatively simple, and involves making sure
your routine anti-parasite preventative treatments administered to
your dog are appropriate. No invasive or expensive treatments are
indicated when disease is caught early. However, the more advanced
the effects or level of infection, the more significant the
permanent damage is likely to be, so the more costly any veterinary
treatment required will be.
How can lungworm be prevented?
Your vet may provide you with some simple treatments that you
can apply to protect your dog from lungworm, as well as other
parasitic worms and fleas.
If you spot slugs and snails in your garden or local park, be
extra vigilant when out walking your dog. Always pick up and safely
dispose of your dog's faeces, and consult your vet as soon as
possible if your dog becomes unwell.
Find out more at www.lungworm.co.uk
Who can I contact for further advice?
The Kennel Club is not a veterinary organisation and is unable
to provide general or case specific veterinary advice. If you
have any questions regarding any of the issues discussed in this
article then please contact your local veterinary practice for
This article was written by Marc Abraham and was originally
published in the Crufts Magazine - www.thecruftsmagazine.com.
Marc Abraham is a vet based in Brighton. He regularly
appears on UK television. For more information about Marc
please visit www.marcthevet.com.