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Dilated Cardiomyopathy in Dogs

Dilated Cardiomyopathy in Dogs

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

What is dilated cardiomyopathy 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 (also known as hypertrophic cardiomyopathy in dogs) chambers (ventricles) or, less frequently, the upper chamber (atria). 

The heart is unable to contract properly and pump blood to the rest of the body, resulting in expansion. Blood accumulates inside the heart before pressure is applied to the valves and outer walls, expanding it. This causes a thinning of the outer walls. 

When this occurs, your puppy's heart has a more difficult time pumping blood throughout the body and to the organs that require it. As the condition progresses, organs such as the lungs and kidneys will begin to malfunction. As the disease progresses, dilated cardiomyopathy will become severe.

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, you should be more cautious about what you feed than the average dog owner. The longer you feed your dog the same food, the more likely he or she will suffer from any excesses or nutritional deficiencies.

As a result, when it comes to DCM and diet issues in dogs, rotate foods on a regular basis, switching between different brands of food with different primary ingredients. Peas, potatoes, lentils, and other legume seeds are primary ingredients in foods linked to the condition.

What are the symptoms of dilated cardiomyopathy in dogs?

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

This disease is often difficult to diagnose in its early stages because early signs of DCM in dogs do not always appear. There is sometimes a lengthy pre-clinical phase. However, your veterinarian may be able to detect subtle or hidden symptoms of the condition during a physical examination. This is why you must bring your dog in to see us.

The following 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 unusually large heart or the presence of fluid in the lungs. Both of these are clear signs of dilated cardiomyopathy.


This test measures the electrical impulses that cause your dog's heart to beat. This test can detect irregular heartbeats (arrhythmia) as well as abnormally fast heartbeats (ventricular tachycardia).


This diagnostic test uses ultrasound to track the movement and shape of your dog's heart in real time. This test allows your veterinarian to examine your dog's heart for tinned muscle walls and the effectiveness of its contractions. This is the definitive test to determine whether your dog has an enlarged heart.

How is dilated cardiomyopathy in dogs treated?

The treatment for your dog's condition may vary depending on the underlying cause. If nutritional issues, such as taurine deficiency, have contributed to its onset, treatment may begin with dietary changes and supplements.

Treatment frequently includes therapies and a variety of medications aimed at strengthening your dog's heart and improving blood circulation. Dogs with breathing problems caused by fluid in the lungs may require oxygen therapy until the fluid drains naturally. Your veterinarian may also prescribe a diuretic or suggest that you drain the fluid manually.

However, the condition is irreversible. It frequently progresses and there is no cure, depending on the underlying cause of your dog's enlarged heart. In these cases, the veterinarian will prioritize treatment to extend your pet's life and make it as comfortable as possible.

The long-term prognosis for DCM in dogs varies significantly. Unfortunately, most dogs diagnosed with congestive heart failure die within 6 months of diagnosis. Dome dogs may only live for a few weeks or months in the most severe cases. Dogs may perform well clinically for one to two 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 dilated cardiomyopathy or other illness in your dog? If symptoms listed here or others have you concerned, contact our Thousand Oaks veterinary team right away. At VSEC we are passionate about providing your pet with the care they need. 

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VSEC Thousand Oaks is accepting new patients! Our board-certified specialists and experienced emergency veterinarians are passionate about restoring good health to animal companions.

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