Skip to Main Content Ask About Financing

DCM in Dogs: Causes, Symptoms & Treatment

Dilated cardiomyopathy (an enlarged heart) in a dog can have numerous potential causes and many severe side effects. Here, our Westport vets list causes of this serious condition, symptoms and treatment options. 

What is DCM in dogs?

In dogs, an enlarged heart (also referred to as Dilated Cardiomyopathy). is a serious condition that refers to the expansion of the heart's lower chambers (ventricles) or, less frequently, the upper chamber (atria). 

The heart is unable to contract properly and push blood to the rest of the body, causing expansion. Blood builds up inside the heart before pressure is put on the heart's valves and outer walls, expanding it. This leads to a thinning of the outer walls. 

When this happens, it becomes more difficult for your pup's heart to pump blood throughout the body, and to the organs that need it. As this condition becomes more advanced, organs such as the lungs and kidneys will begin to malfunction. The disease's progression will eventually make dilated cardiomyopathy severe.

DCM in Dogs, Westport Vets

Causes of an Enlarged Heart in Dogs

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

While dilated myopathy does not have a definitive cause, many factors can contribute to the development of the condition in your pet. Nutritional deficiencies in taurine and carnitine have been proven to influence the development of an enlarged heart in dogs.

In addition, other factors such as genetics and infectious diseases can play a role in cardiomyopathy in dogs. Some dog breeds - especially large breeds - are known to be predisposed to developing this condition due to taurine insufficiency. They include:

  • Newfoundland
  • American Cocker Spaniels
  • English Setter
  • Golden Retriever
  • Labrador Retriever
  • Saint Bernard

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

  • Boxers
  • Irish Wolfhounds
  • Great Danes
  • Doberman Pinschers

If your dog is one of these breeds, take more caution about what you're feeding than the average dog owner. The longer you feed your dog the same food, the more likely he or she will be impacted by any excesses or nutritional deficiencies it contains.

Therefore, when it comes to DCM in dogs and diet issues, rotate foods regularly, changing between different brands of foods with different primary ingredients. Foods with primary ingredients of peas, potatoes, lentils and other legume seeds have been linked to the condition. 

What are signs of DCM in dogs?

Signs of dilated cardiomyopathy in dogs may range from mild to severe as the condition progresses.

This disease is often difficult to diagnose in its early stages, as early signs of DCM in dogs do not often appear. There is sometimes a long pre-clinical phase. 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 bring your pooch in to see us.

Our board-certified internist is able to diagnose and treat challenging cases with access to numerous diagnostic tools and treatment methods.

These are some of the most common symptoms of DCM in dogs:

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

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 which 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 a number of 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, the condition is 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.

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, dome 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.

Are you seeing signs of DCM or other illness in your dog? If symptoms listed here or others have you concerned, contact our Westport veterinary team right away. At Westport Veterinary Associates we are passionate about providing your pet with the care they need. 

New Patients Welcome

Westport Veterinary Associates has been providing comprehensive veterinary care for your cherished pets in Fairfield County since 1993.

Contact Us

Book Online (203) 259-3647