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Dogs with Enlarged Hearts (Dilated Cardiomyopathy): Causes, Treatments & Symptoms

Dogs with Enlarged Hearts (Dilated Cardiomyopathy): Causes, Treatments & Symptoms

Dilated cardiomyopathy, also known as an enlarged heart in dogs, can be caused by various factors and can have severe consequences. Our cardiologist vets in Gaithersburg will provide explanations of the causes, symptoms, and treatments of this critical condition.

What is an enlarged heart in a dog?

Dilated cardiomyopathy, also known as an enlarged heart in dogs, is a severe condition that occurs when the lower chambers of the heart (ventricles) or, less commonly, the upper chambers (atria) expand. This happens when the heart is unable to contract and pump blood out properly, leading to blood accumulation in the heart. This accumulation of blood exerts pressure on the outer walls and valves of the heart, causing thinning and expansion of the heart walls. 

An enlarged heart in dogs makes it difficult for the heart to effectively pump blood to the organs that require it, leading to a reduction in the function of organs such as the lungs and kidneys as the condition progresses. This is why dilated cardiomyopathy is a severe and critical condition that requires immediate attention.

What causes an enlarged heart in dogs?

Enlarged hearts can develop in dogs of any age or breed, but it's more common in dogs between four and ten years old. Although there isn't a definite cause for dilated cardiomyopathy, several factors are known to contribute to its development in your pet. Nutritional deficiencies in carnitine and taurine have been found to be linked to the development of an enlarged heart in dogs. 

Other factors, such as infectious diseases and genetics, can also contribute to this condition's development. Some breeds of dog, especially large breeds, are known to be predisposed to developing the condition, including:

  • 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

What are the symptoms of an enlarged heart in dogs?

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

It can be challenging to identify this condition in its initial stages, but your veterinarian can potentially spot minor early indications during a comprehensive physical check-up. Therefore, scheduling regular routine exams for your furry friend is crucial.

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

How is an enlarged heart diagnosed in dogs?

During a regular check-up, your veterinarian may notice signs of an enlarged heart in your dog. However, a conclusive diagnosis of dilated cardiomyopathy will require additional testing to determine whether any of the symptoms mentioned are related to the condition.


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. An irregular heartbeat (arrhythmia) or an abnormally fast heartbeat (ventricular tachycardia) can both be detected using this method. 


Our ultrasound diagnostic test allows your veterinarian to monitor your dog's heart in real-time to check for any issues with the heart muscle walls and the effectiveness of contractions. This is the most reliable way to determine if your furry friend is experiencing an enlarged heart.

What is the treatment for an enlarged heart in dogs?

The treatment for an enlarged heart in dogs depends on the underlying cause. If the cause is related to nutrition, such as a deficiency in taurine, treatment can simply involve changes to the dog's diet and supplements. However, most often, treatment involves a combination of medications and therapies to strengthen the dog's heart and improve blood circulation.

For dogs experiencing breathing difficulties due to fluid in their lungs, oxygen therapy may be necessary until the fluid drains naturally. Additionally, a vet may prescribe a diuretic or manually drain the fluid from the lungs. Typically, long-term hospitalization is not necessary unless the condition is severe and persistent.

Dilated cardiomyopathy is often a progressive condition, and there is no cure. Treatment is aimed at lengthening your treasured companion's life and making your pet 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.

If your canine companion has heart issues or is at risk, our team of veterinarian cardiologists in Gaithersburg can provide assistance. You may request a referral from your regular veterinarian or reach out to us directly.

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Veterinary Referral Associates is accepting new patients! Our experienced vets are passionate about the health of Gaithersburg companion animals. Get in touch today to book your pet's first appointment.

Contact (301) 926-3300