---
title: "Heartworm in Dogs UK"
description: "UK guide — native heartworm is rare in Britain but a serious risk for dogs travelling to southern Europe. Mosquito spread, prevention before travel."
url: "https://pethealth.org.uk/health/heartworm-in-dogs"
canonical: "https://pethealth.org.uk/health/heartworm-in-dogs"
date_published: "2026-06-23"
date_modified: "2026-06-25"
source: "PETHEALTH+"
---

# Heartworm in Dogs UK

**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](/health/heartworm-vs-lungworm-dogs-uk).

## 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](/health/heartworm-vs-lungworm-dogs-uk).

## How dogs get heartworm

1. Mosquito bites an infected dog or wild canid
2. Mosquito picks up **microscopic larvae**
3. Mosquito bites your dog — larvae enter the bloodstream
4. 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?](/health/why-is-my-dog-coughing)
- **Exercise intolerance** — see [Why is my dog panting heavily?](/health/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](/health/lungworm-in-dogs-uk)
- Routine **intestinal worming** — [Dog worming schedule](/health/dog-worming-schedule-uk)
- **Tick prevention** — see [Lyme disease in dogs UK](/health/lyme-disease-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](/health/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.

## Related guides

- [Heartworm vs lungworm in dogs UK](/health/heartworm-vs-lungworm-dogs-uk)
- [Lungworm in dogs UK](/health/lungworm-in-dogs-uk)
- [Travelling with pets UK](/health/travelling-with-pets-uk)
- [Fleas and ticks in pets](/health/fleas-and-ticks-in-pets)

## FAQs

### 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.

## Sources

- [BVA — Parasite treatments](https://www.bva.co.uk)
- [PDSA — Lungworm in dogs](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub)
- [Blue Cross — Travelling with your dog](https://www.bluecross.org.uk/pet-advice)

Canonical HTML: https://pethealth.org.uk/health/heartworm-in-dogs
Last modified: 2026-06-25