Is heartworm common in the UK?

Native UK heartworm infection is uncommon. The main UK concern is lungworm (Angiostrongylus). Heartworm matters for dogs travelling to or imported from southern Europe and other warm regions where mosquitoes carry the parasite.

How do dogs get heartworm?

Infected mosquitoes inject microscopic larvae during a bite. Larvae mature over months into worms in the heart and pulmonary arteries. Heartworm does not spread directly between dogs.

Do UK dogs need heartworm prevention?

Dogs that stay in the UK year-round rarely need heartworm prevention. Dogs travelling to heartworm-endemic countries should receive vet-prescribed prevention before and during travel.

What is the difference between heartworm and lungworm?

Different parasites with different spread. UK lungworm spreads via slugs and snails and is common in Britain. Heartworm spreads via mosquitoes and is a travel risk. See our comparison guide.

Dog Health

Heartworm in Dogs UK

By Kaiser Khan, EditorPublished 23 June 2026Last updated 25 June 20263 min read

Quick answer

Heartworm is rare in native UK dogs — the parasite spreads via mosquito bites, not dog-to-dog contact. UK owners should prioritise lungworm prevention. Heartworm prevention matters for dogs travelling to southern Europe and other warm regions. See Heartworm vs lungworm UK.

Key takeaways

Infected mosquitoes inject microscopic larvae during a bite. Larvae mature over months into worms in the heart and pulmonary arteries. Heartworm does not spread directly between dogs.
Dogs that stay in the UK year-round rarely need heartworm prevention. Dogs travelling to heartworm-endemic countries should receive vet-prescribed prevention before and during travel.

A wider perspective: the Karachi street-dog welfare appeal from the non-profit World Animal Rescue Network.

Heartworm in the UK context

Heartworm (Dirofilaria immitis) larvae are spread by infected mosquitoes. Adult worms live in the heart and pulmonary arteries, causing progressive heart and lung disease.

According to the BVA, native UK heartworm infection is uncommon. Cases in Britain are usually linked to:

Travel abroad — southern Europe, Mediterranean countries
Imported dogs from endemic regions
Very rare local transmission — not the main UK parasite concern

For most UK-only dogs, lungworm (Angiostrongylus vasorum) — spread by slugs and snails — is the priority. Full comparison: Heartworm vs lungworm in dogs UK.

How dogs get heartworm

Mosquito bites an infected dog or wild canid
Mosquito picks up microscopic larvae
Mosquito bites your dog — larvae enter the bloodstream
Larvae mature over months into adult worms in the heart

Heartworm is not contagious between dogs directly.

Symptoms

Early infection may show no signs. As disease progresses:

Soft persistent cough — see Why is my dog coughing?
Exercise intolerance — see Why is my dog panting heavily?
Reduced appetite and weight loss
Swollen belly from fluid (heart failure)
Collapse in severe cases

Many dogs are diagnosed on routine travel screening before symptoms appear.

Prevention for UK owners

Dogs staying in the UK

Focus on lungworm prevention — see Lungworm in dogs UK
Routine intestinal worming — Dog worming schedule
Tick prevention — see Lyme disease in dogs UK

Dogs travelling abroad

Before travel to heartworm-endemic regions:

Discuss heartworm prevention with your vet before departure
Start prevention as advised — timing depends on the product
Consider blood testing on return if exposure occurred
See Travelling with pets UK

Never give preventive medication without veterinary guidance — dogs with unknown heartworm status need testing first.

Treatment

Treating established heartworm is lengthy, costly, and carries risks — strict rest and veterinary protocols are required. Prevention is far safer than treating active disease.

Cats and heartworm

Cats can be affected in endemic regions but are less typical hosts. Prevention strategy depends on travel exposure — ask your vet.

Sources & further reading

This guide draws on the publicly available UK advice listed below. Follow the links for the relevant guidance or the organisation's broader care resources.

PETHEALTH+ is independent. These organisations do not sponsor, approve, or partner with this website. Editorial sources and further reading (last updated 2026-06-25).

Continue exploring

Follow the connections between guides to explore related care and conditions.

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Also see symptoms, symptom checker, and poison guide.

Frequently Asked Questions

Is heartworm common in the UK?: Native UK heartworm infection is uncommon. The main UK concern is lungworm (Angiostrongylus). Heartworm matters for dogs travelling to or imported from southern Europe and other warm regions where mosquitoes carry the parasite.
How do dogs get heartworm?: Infected mosquitoes inject microscopic larvae during a bite. Larvae mature over months into worms in the heart and pulmonary arteries. Heartworm does not spread directly between dogs.
Do UK dogs need heartworm prevention?: Dogs that stay in the UK year-round rarely need heartworm prevention. Dogs travelling to heartworm-endemic countries should receive vet-prescribed prevention before and during travel.
What is the difference between heartworm and lungworm?: Different parasites with different spread. UK lungworm spreads via slugs and snails and is common in Britain. Heartworm spreads via mosquitoes and is a travel risk. See our comparison guide.