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Dilated Cardiomyopathy (DCM) in Dogs

Dilated Cardiomyopathy (DCM) in Dogs

An enlarged heart (also known as dilated cardiomyopathy) in a dog can be caused by numerous issues and have many severe side effects. In this post, our Gaithersburg vets discuss causes, symptoms and treatment options for this serious condition.

What is DCM in dogs?

Also referred to as dilated cardiomyopathy in dogs, an enlarged heart in dogs is a serious condition that involves the expansion of the heart's lower chambers (ventricles) or, less often, the upper chamber (atria). 

Expansion occurs because the heart is unable to contract properly and push blood to the rest of the body. Blood accumulates inside the heart before pressure is applied to the heart's valves and outer walls, expanding it. The outer walls then start to grow thinner. 

When this occurs, it becomes more difficult for blood to reach the organs that need it. As the condition progresses and becomes more severe, the lungs, kidneys, and other organs will start to malfunction. 

Causes of Enlarged Heart in Dogs 

While dogs of any age or breed can have an enlarged heart, the condition is much more common in dogs between 4 and 10 years of age. 

While there's no definitive cause for dilated cardiomyopathy, many factors can promote the development of this condition in your pet. Nutritional deficiencies in carnitine and taurine have been proven to influence the development of an enlarged heart in dogs. 

Other factors such as genetics and infectious diseases may also contribute to cardiomyopathy in dogs.

DCM in Dogs & Dietary Factors

Large dog breeds in particular are known to be predisposed to developing this condition due to taurine insufficiency. Taurine is an important amino acid that dogs typically manufacture themselves as long as they eat enough of the necessary building blocks. 

Dog breeds that are thought to have a genetic predisposition to taurine deficiency include: 

  • American cocker spaniels 
  • English setters  
  • Newfoundlands 
  • Golden retrievers 
  • Labrador retrievers 
  • Saint Bernards 

While other breeds are genetically prone to DCM, they are not linked to taurine deficiency. These include:

  • Great Danes 
  • Boxers
  • Doberman Pinschers 
  • Irish wolfhounds 

If your dog is one of these breeds, be more careful about their diet than the average dog owner. The longer you feed your dog the same food, the higher the risk they'll be impacted by any excesses or nutritional deficiencies the food may contain. 

Therefore, to lower the risk that diet issues will become a factor in the development of DCM in dogs, we recommend rotating foods regularly, changing between different food brands that list various primary ingredients. Foods with primary ingredients of potatoes, peas, lentils and other legume seeds have been linked to this condition. 

What are signs of DCM in dogs?

Dilated cardiomyopathy is often difficult to diagnose in its early stages, since early symptoms of DCM in dogs do not often appear and the pre-clinical phase may be long.

When they do occur, symptoms may appear mild at first, then grow more severe as the condition progresses. That said, your vet may be able to identify subtle or hidden signs of the condition during a physical examination. 

This is why it's imperative to being your dog in to see us. Our internal medicine specialist can diagnose and treat challenging cases, and has access to many diagnostic tools and treatment methods. 

Here are some common DCM symptoms in dogs: 

  • Abdominal distension 
  • Anorexia
  • Coughing
  • Heart murmur
  • Labored breathing 
  • Lethargy 
  • Muffled breathing or crackling sound while breathing 
  • Panting
  • Sudden collapse
  • Weak or irregular pulse 

Diagnosing an Enlarged Heart in Dogs

While a routine physical examination can suggest to your vet that your pup may have an enlarged heart, a final diagnosis will require further diagnostic testing to determine if the above symptoms are a result of dilated cardiomyopathy.


A chest x-ray of your dog may reveal abnormalities in their heart and lungs such as an unnaturally large heart or the presence of fluid in the lungs. Both of these are strong indicators of dilated cardiomyopathy.


This test monitors the electric impulses that cause your dog’s heart to beat. This test can reveal heart issues such as an irregular heartbeat (arrhythmia) and an abnormally fast heartbeat (ventricular tachycardia) can both be detected using this method.


This diagnostic test uses ultrasound to monitor the movements and shape of your dog’s heart in real time. This test allows your vet to check your dog’s heart for tinned muscle walls and the efficacy of their heart’s contractions. This is the definitive test to determine whether your canine companion can be diagnosed with an enlarged heart or not.

Treatment of Dilated Cardiomyopathy in Dogs

Treatment may vary depending on the underlying cause of the condition in your dog. If nutritional issues such as taurine deficiency have influenced its onset, treatment may begin with dietary changes and supplements.

Treatment often involves therapies and several medications designed to strengthen your dog's heart, which will assist with blood circulation. Dogs experiencing breathing problems due to fluid in the lungs may require oxygen therapy until the fluid drains naturally from their lungs. Your vet may also prescribe either a diuretic to drain the fluid or do this manually.

However, when it comes to treating DCM in dogs, symptoms are not reversible. It often turns progressive and there is no cure, depending on the underlying cause of your dog's enlarged heart. In these cases, the vet will focus treatment on extending your furry friend's life and making it as comfortable as possible.

The long-term prognosis for DCM in dogs varies considerably. Unfortunately, most dogs with signs of congestive heart failure when they are diagnosed die as a result of the disease within 6 months. In the most severe cases, some dogs may survive only weeks to a few months. Sometimes, dogs may do well clinically for 1 to 2 years. 

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Have you noticed signs of DCM or other illness in your dog? If symptoms listed here or others have you concerned, contact our Gaithersburg vets today. We are passionate about providing your pet with quality care.

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Contact (301) 926-3300