DCM in dogs (Dilated Cardiomyopathy)


  • Dilated Cardiomyopathy (DCM) is a disease that causes the heart muscle to become thin, weak and floppy.
  • It’s most common in large and giant breed dogs, but can also affect certain types of Spaniel.
  • DCM usually develops gradually (over months to years) before it starts to cause symptoms.
  • DCM isn’t curable, but can usually be managed with medication.
  • DCM tends to get gradually more severe over time, but the earlier a dog is diagnosed and treated the better their outlook.
  • It’s important to be aware that DCM can occasionally cause sudden death, sometimes even before any other symptoms have developed.

General information

DCM (Dilated Cardiomyopathy) is a disease that affects the heart muscle, causing it to become thin and weak. Dogs with DCM develop a big, floppy heart that struggles to pump blood around the body and usually an irregular heart beat. DCM can affect any breed of dog, but is most common in large/giant breed dogs and certain types of Spaniel.

In most cases, DCM is a genetic disease (meaning it’s passed from parent to puppy in their genes), but there are some reports of dogs developing it due to poor diet, a virus, toxin, or certain medications that affect the heart.

Many cases of DCM go undetected for years because it tends to develop very gradually. Fortunately, there are screening programs available that can now detect DCM in it’s early stages.

DCM affects the heart muscles, causing the heart to become big and floppy


DCM tends to develop for a number of months to years before it starts to cause symptoms. However, once the heart has been significantly damaged (and begins struggling to pump blood), the following symptoms are likely to develop:

  • Low energy
  • Exercise intolerance (struggling to keep up on walks)
  • Collapse/ fainting
  • A heart murmur and/or arrhythmia (detected by your vet)

As DCM progresses and the heart starts to fail, more severe symptoms usually develop such as:

It’s important to be aware that in some cases, DCM can cause sudden death (most commonly in dogs that have collapsing/fainting episodes). Sadly, in some cases, this can occur before any other symptoms develop.


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).
  • An ultrasound scan to see inside your dog’s heart (if they have DCM, your vet will be able to see thin heart walls, enlarged chambers, and your dog’s heart struggling to pump).
  • X-rays. If your dog has DCM, their heart is likely to be bigger than normal on x-rays, and there may be fluid on their lungs (a sign of heart failure).
  • Blood tests such as ‘ProBNP’, a chemical that shows if the heart muscle is being stretched and struggling to pump blood.


DCM can’t be cured, but there are heart medications that can be used to slow it down and help control the symptoms it causes. The treatment your dog needs will depend on what stage of DCM they have. 

Treatment for dogs without symptoms

If your dog has been diagnosed with DCM, but doesn’t have any obvious symptoms, they may still benefit from medication. A drug called ‘pimobendan’, has been shown to slow down the progression of DCM in some dogs, and in addition, if they have a fast or irregular heartbeat, this could be improved with an anti-arrhythmic medication.

Treatment for dogs with symptoms

if your dog has symptoms of DCM, or is going into heart failure, your vet may recommend heart medications, including:

  • Diuretics such as ‘furosemide’ and ‘spirinolactone’, to help remove fluid (from the lungs and belly), that often builds-up if the heart is struggling.
  • Inodilators such as ‘pimobendan’, to help the heart pump more effectively.
  • ACE inhibitors such as ‘benazepril’, to make it easier for the heart to pump blood around the body.
  • Anti-arrhythmic drugs if your dog has an irregular heartbeat.
  • Additional supplements - some dogs with DCM benefit from heart supplements such as L-carnitine, Taurine and certain fish oils (always speak to your vet before starting your dog on a supplement).


Unfortunately, it’s impossible for anyone to predict exactly how long your dog will live because each case is so different. Some dogs live for several years (especially if they are diagnosed and treated early), but others (with severe DCM/heart failure), only live a few weeks. It’s important to be aware that although there are medications available to help control the symptoms of DCM, it’s a serious condition that in most cases, shortens life expectancy. If your dog has DCM and stops responding to treatment, or has a poor quality of life, sadly it may be necessary to make the difficult decision to put them to sleep.

When to contact your vet

If your dog has DCM and they appear to be getting worse, contact your vet.

Contact your vet if you have noticed any of the symptoms listed above, or you’re worried about your dog’s heart (especially if they are a breed prone to DCM).

EMERGENCY - If your dog has collapsed or is struggling to  breathe, contact your vet immediately for an emergency appointment.

Breeds and screening

DCM is common in large and giant breed dogs such as:

It can also affect:

There are screening programs available to check ‘at-risk’ breeds for DCM. If you have an at ‘at-risk’ breed, speak to your vet about having them screened. It’s recommended that screening is carried out every year from 3 years old.


Treatment for DCM can be very expensive because it’s a condition that can need life-long monitoring and treatment. It’s important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is right for your dog. There is often more than one treatment option, so if one doesn’t work for you and your dog then your vet may be able to offer another.

Consider taking out dog insurance as soon as you bring your dog home, before any signs of illness start. This will give you peace of mind that you have some financial support if they ever become unwell. 

Published: August 2020

Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.