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Is An Enlarged Heart in Dogs Always Fatal?

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If you suspect your dog has an enlarged heart or your vet diagnosed your dog with this condition, you may be wondering if an enlarged heart in dogs is always fatal. The heart is a pump, and as a pump, it sadly is not designed to last forever. In a dog with an enlarged heart, the heart is struggling to work and cannot pump blood efficiently as it should. When the heart fails to work as it should, it has a negative impact on the dog's lungs, liver, and other body systems which can cause a cascading chain of events. Unfortunately, once a dog develops an enlarged heart, there is no way to reverse it.

Gray muzzles need good dental care

Gray muzzles need good dental care

What Happens to the Heart

The medical term for an enlarged heart in dogs is "canine dilated cardiomyopathy. "The word "canine" refers to dogs, the word "dilated" refers to an enlargement and the word "cardiomyopathy" simply means "disease of the heart muscle."

Dilated cardiomyopathy commonly affects large and giant breed dogs especially, Great Danes, Doberman, Irish wolfhounds, Scottish deerhounds, Saint Bernards, bullmastiffs, Newfoundlands and boxers. In some cases, English and American cocker spaniels are affected too, even though they are medium-sized dogs. The age of onset is typically anywhere between 4 and 10 years old.

In dogs suffering from dilated cardiomyopathy, their heart suffers from a decrease in myocardial contractility, meaning that the heart doesn't contract and pump blood as effectively it should. As the heart weakens over time, it can't pump enough blood to meet the body's needs and progresses into heart failure.

Slowing Down Problems

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When a dog develops a condition like dilated cardiomyopathy, it's important to manage this condition with the help of several drugs. There are several medications that can help the heart not to have to work too hard so that the dog feels better. Often, for advanced cases, treatments consists of a combination of a diuretic, an ACE inhibitor, and a drug known as pimobendan.

When the heart's pumping ability decreases, fluid will back up into the lungs and will buildup in the dog's body. A drug known as Lasix ( generic furosemide), is a diuretic that can help decrease the amount of extra fluids accumulating in the dog's lungs, chest and/or abdomen. This use of this drug is very important because it decreases the workload of the heart by increasing urinary output of fluids by affecting the kidneys. Another example of a diuretic is spironolactone.

Enalapril or benazepril are drugs known as ACE inhibitors and they mainly work by reducing vascular resistance. ACE stands for “angiotensin converting enzyme."

Pimobenden, also known as Vetmedin, is a positive inotropic vasodilator that dilates the blood vessels and arteries throughout the dog's body, providing less resistance to blood flow. This facilitates the heart's ability to pump blood to where it needs to go.

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On top of drugs to help the heart, vets may recommend a diet that reduces sodium intake. A diet low in sodium helps control fluid retention. There are special prescription veterinary diets specifically crafted for dogs with heart problems.

" When I have cases who don't respond to the enalapril (I use benazepril but it's pretty much the same thing) and the lasix (same thing as furosemide) then I find that the addition of the medication Vetmedin can make a big difference in the symptoms." ~Dr. Dan

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A Progressive Condition

Dilated cardiomyopathy is a progressive disease and the heart can try to adapt to problems only up to a certain point. Sure, the administration of oral medications can help the heart adapt further, but at some point, it no longer can be controlled or helped, explains veterinarian Dr. Bruce. Unfortunately, there is nothing that can make a dog's enlarged heart size go back to normal.

When the heart is not working well, the rest of the body pays the price and the dog ends up developing what's known as cardiac cachexia, a metabolic disorder causingprogressive weight loss due to loss of muscle mass and fat stores. Advanced heart disease causes progressive weakness, exercise intolerance, labored breathing, coughing and even collapse.

What's the average life expectancy of a dog suffering from decreased myocardial contractility? Generally, most affected dogs will succumb to the disease anywhere between 6 months to 2 years, explains Barret J. Bulmer, a board-certified veterinarian specializing in cardiology. The goal is to manage the condition and put less strain on the heart.

“Although in most dogs these goals can be achieved for a period of time, there is typically no cure, and most dogs with dilated cardiomyopathy and congestive heart failure will ultimately succumb to their disease." ~Dr. Bulmer 

Can Dogs Get a Heart Transplant?

As seen, there is no cure for dilated cardiomyopathy in dogs as the disease is progressive. Even with the best medications, they will eventually stop working and the heart will give up eventually. The condition is therefore always fatal. Dog owners sometimes wonder whether a heart transplant is an option.

While heart transplants are often done in humans, in dogs it is unheard of, other than the rare experimental studies one may sometimes stumble upon in literature. And for those wondering whether the hearts of dogs who are euthanized daily in shelters could be used for a transplant, the answer is no. Euthanized dogs will have euthanasia drugs in their hearts and that would be toxic and unable to beat again, explains Dr. Rebecca. 

If your dog is suffering from dilated cardiomyopathy and you want to go an extra mile and explore further options, you may find it useful to consult with a board-certified veterinarian specializing in cardiology. Often heart disease can be managed for many months or even years when the right protocols are in place.


  • DVM360, Oh my, myopathy!?!
  • DVM360, Managing dilated cardiomyopathy (Proceedings)

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