Lungworm, slugs and slug-bait – considering the risks
What is lungworm?
‘Lungworm’ – a life-threatening parasite in dogs – has been attracting a great deal of attention in the veterinary press over the last decade, but has been previously regarded as a problem limited to the southern part of the UK. Since its recognition in the UK more than 30 years ago, lungworm has been spreading throughout the UK and northern Europe. This change in distribution is, at least in part, due to a changing climate and we do indeed see this at Northwest Surgeons.

Lungworm may go undiagnosed until severe life-threatening signs develop – dogs may be infected for months before developing clinical signs and may then die within hours of showing signs of illness.
The scientific name for dog lungworm is Angiostrongylus vasorum – but other lungworms exist in other species. Looks pretty nasty, doesn’t it?
Angiostrongylus is contracted by the dog eating a slug or snail harbouring lungworm larvae.
The larvae then migrate through the body to reach the major blood vessel between the heart and the lungs (pulmonary artery). Here the larvae mature to adults and lay eggs. The eggs hatch to immature larvae which migrate into the lung tissue and are coughed up and swallowed. The larvae end up in the dog’s faeces, to be ingested by other slugs and snails. Click here to view the lifecycle. 
What problems can lungworm cause?
Cough, coughing blood, breathing problems
Lethargy
Heart failure
Collapse
Sudden death
Which dogs are at risk?
The majority of dogs affected are young dogs, but we have diagnosed cases in mature and elderly dogs. As slugs and snails are fairly ubiquitous, most dogs are potentially at risk. Studies show that very few infective larvae are found in the slugs’ or snails’ slime trails, but a puddle contaminated with a dead slug may contain huge numbers of larvae.
Dogs may inadvertently or intentionally ingest slugs or snails. Many of the dogs that we have diagnosed have not been seen by their owner to eat slugs or snails.
How is lungworm diagnosed?
The initial suspicion is based upon the clinical signs, but x-rays, heart scan, blood tests, blood clotting tests and faecal examination for parasites (Baermann examination) will form part of the diagnostic work-up.
Can lungworm be treated?
With early diagnosis, lungworm can be cured with no lasting permanent damage. Unfortunately, significant damage may already have occurred by the time of diagnosis.
Can lungworm be prevented?
Preventing exposure to slugs and snails is difficult, but a monthly spot-on treatment is available to prevent lungworm. The treatment should be used year-round but is particularly important during periods of high snail and slug activity.
What about eliminating slugs and snails?
The most common slug bait – metaldehyde – is extremely toxic to pets and we would not recommend using this.
Use some safer alternatives:
- Encourage natural slug and snail predators such as hedgehogs or birds.
- Buy ‘Nemaslug’ – a live nematode worm that kills slugs
- Place non-toxic slug traps – either homemade or proprietary
- Adhesive copper tape around pots to protect the plants.
What should I do now to protect my dog?
Discuss lungworm prevention – along with other parasite control measures – with your veterinary surgeon. The licensed preventative spot-on is a prescription medication – it cannot be bought in supermarkets or pet stores.
You will still need to use a regular dewormer in tablet form.
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