Heartworm in dogs

By
✔ MRCVS
BSc
BVM&S
FHEA
Updated October 16, 2025
6 min read

Overview

Symptoms

2

Risk

Diagnosis

Vet treatment

Home treatment

Prevention

When to worry

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Heartworm in dogs

By
✔ MRCVS
BSc
BVM&S
FHEA
Updated October 16, 2025
6 min read

Heartworm is a serious infection, causing heart disease and even death in affected dogs. Mosquitoes carry the heartworm parasite and transmit infection when they bite. Heartworm isn’t present in the UK, but it’s a hazard to dogs living or travelling abroad with their owners.

Heartworm in dogs is caused by a parasite called Dirofilaria immitis. We don't have heartworm in the UK, but it’s endemic in parts of Europe and warm countries around the world. Symptoms of heartworm range from mild to life-threatening. They include coughing, weakness and difficulty breathing. Heartworm is preventable, with regular monthly prescription medicine. Talk to a vet for early advice if you are planning to travel to countries which have heartworm.

What is heartworm in dogs? >What is heartworm in dogs? [Overview

What are the symptoms of heartworm in dogs? >What are the symptoms of heartworm in dogs? [Symptoms

Are some dogs at more risk of heartworm infection? >Are some dogs at more risk of heartworm infection? [Risk

How do vets diagnose heartworm in dogs? >How do vets diagnose heartworm in dogs? [Diagnosis

How do vets treat heartworm in dogs? >How do vets treat heartworm in dogs? [Vet treatment

How to care for a dog with heartworm at home >How to care for a dog with heartworm at home [Home treatment

How to prevent heartworm infections in dogs >How to prevent heartworm infections in dogs [Prevention

When to worry about heartworm infection in your dog >When to worry about heartworm infection in your dog [When to worry

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