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Enlarged Heart in Dogs: Causes, Symptoms, & Treatment

Enlarged Heart in Dogs: Causes, Symptoms, & Treatment

An enlarged heart in a dog, also known as dilated cardiomyopathy, is a condition with many causes and potentially life-threatening effects. Here, our Vienna veterinary team discusses the causes, signs, and treatment of an enlarged heart in dogs.

What is an enlarged heart in a dog?

An enlarged heart in dogs (Dilated Cardiomyopathy) is a serious condition that describes the expansion of the lower chambers of the heart (ventricles), or less commonly, its upper chamber (atria).

A dog’s heart will expand in this way when it is unable to properly contract and push blood out from it and to the rest of the body. Blood accumulates in the heart and its pressure pushes at the outer walls and valves of the heart, expanding it and thinning its outer walls.

When a dog’s heart is enlarged in this way, it becomes even more difficult for the pup to pump blood around its body and to the organs that need it. As this condition progresses, the dog’s organs, especially lungs, and kidneys, will often begin to reduce in function. This progression is what makes dilated cardiomyopathy very serious.

Causes of an Enlarged Heart in Dogs

An enlarged heart may appear in any dog age or breed, However, it is much more common in dogs between the ages of four and ten years old. 

While there is no definitive cause for dilated cardiomyopathy, there are several known factors that can contribute to its development in your pet. Nutritional deficiencies in carnitine and taurine have been proven to factor into the development of an enlarged heart in dogs. 

As well, other factors such as infectious diseases and genetics can contribute to this condition’s development. Some breeds of dog, especially large breeds, are known to be predisposed to developing the condition, they include:

  • Irish Wolfhounds
  • Newfoundland Retrievers
  • American Cocker Spaniels
  • Boxers
  • Dalmatians
  • Doberman Pinschers
  • Springer Spaniels
  • Labrador Retrievers
  • Tibetan Terriers
  • Welsh Corgis
  • English Cocker Spaniels
  • German Shepherds
  • Great Danes
  • Saint Bernards
  • Scottish Deerhounds

Signs of Dilated Cardiomyopathy

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

Often, it is very difficult to diagnose in its early stages. However, your vet may be able to detect subtle or hidden signs of this condition in the course of a complete physical examination. Because of this, it is very important to bring your four-legged companions in for routine exams to provide as many opportunities as possible for your Vienna vet to uncover early signs of dilated cardiomyopathy.

The following are some of the most common symptoms of an enlarged heart:

  • 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 Vienna vet that your pup may have an enlarged heart, a final diagnosis will require further 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.

Treating Dilated Cardiomyopathy in Dogs

Treatment of an enlarged heart depends almost entirely on the root cause of this condition in your specific dog. If it was brought on by nutritional issues such as a taurine deficiency, treatment can begin with something as simple as dietary changes and supplements. 

Treatment most often involves a series of medications and therapies intended to strengthen your furry companion’s heart and allow them to better circulate their blood. Dogs suffering from breathing issues brought on by fluid in their lungs may require oxygen therapy until the fluid drains from their lungs naturally, because of a prescribed diuretic, or because your vet drains them manually. 

Unless your dog is continually and severely affected by this condition, long-term hospitalization is usually not required. 

However, depending on the underlying cause of your dog’s enlarged heart, it is often progressive and there is no cure. In these cases, treatment is aimed at lengthening your treasured companion’s life and making it as comfortable as possible.

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.

Is your dog showing symptoms of an enlarged heart? Contact our Vienna vets right away.

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