Dilated cardiomyopathy in dogs – signs and what to do

Updated 2026-09-30 · 2 sources

Based on: PDSA, Science for Animal Welfare (UFAW), Genetic Welfare Problems of Companion Animals

Contact a vet today

Contact your vet today if you think your dog has this – it can become serious. Dilated cardiomyopathy is a disease that makes the heart muscle thin, weak and floppy.

What to do now

What you can do now

Contact your vet today.
Note when it started, how often it happens and what else you see.
Take a photo or short video to show the vet.
Keep fresh water available.
Let your dog rest somewhere calm.

Don't

Do not give your dog any human medicine.
Do not wait if it gets worse.
Do not wait if your dog collapses or is struggling to breathe.

What it is

Dilated cardiomyopathy is a disease that causes the heart muscle to become thin, weak and floppy.^[1] It usually develops gradually over months to years before it starts to cause symptoms.^[1] Dilated cardiomyopathy cannot be cured, but heart medications may slow it down and help control the symptoms it causes.^[1]

Signs

Low energy
Struggling to keep up on walks
Collapse or fainting
A heart murmur or irregular heartbeat detected by your vet
Breathlessness
Coughing, especially in the morning
Weight loss
Swollen legs
A bloated belly
Cold legs and ears

Usually gradual, over months to years

Causes and risk factors

Dobermann
Irish Wolfhound
Great Dane
Newfoundland
Boxer
Cocker Spaniel
Springer Spaniel

How a vet finds out

Blood tests
X-rays
Ultrasound
ECG to check the heart rhythm

How vets treat it

Medication
Diuretics such as furosemide and spirinolactone
Inodilators such as pimobendan, to help the heart pump more effectively
ACE inhibitors such as benazepril
Anti-arrhythmic drugs if your dog has an irregular heartbeat
Additional supplements
Treatment based on the stage of dilated cardiomyopathy

Breeds prone to this

Veterinary charities list these breeds as more likely than others to get this condition. Each breed page lists the inherited conditions documented in the breed.

What the experts say

“If your vet suspects your dog has DCM, they may want to run some of the following tests to confirm the diagnosis: An ECG to check your dog’s heart rhythm (if they have DCM, they may have an arrhythmia/irregular heartbeat).”
— PDSA [1]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

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Common questions

What signs can dilated cardiomyopathy cause?

Signs can include low energy, struggling to keep up on walks, collapse or fainting, breathlessness, coughing, weight loss, swollen legs and a bloated belly.^[1]

How might a vet check for dilated cardiomyopathy?

A vet may use an ECG to check your dog's heart rhythm; dogs with dilated cardiomyopathy may have an irregular heartbeat.^[1]

When is it an emergency?

If your dog has collapsed or is struggling to breathe, contact your vet immediately for an emergency appointment.^[1]

Sources

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages