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4 Dangers of an Enlarged Heart in Dogs

Having a Large Heart Isn't Always a Good Thing

By January 03, 2014 | See Comments

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An englarged heart in dogs can be potentially fatal if not diagnosed and treated promptly. So it's important to know the causes, symptoms, and possible dangers of an enlarged heart.

Heart health can be a big concern for dog owners, especially those who are raising certain breeds. For instance, the Doberman Pinscher, Boxer, Scottish Deerhound, Irish Wolfhound, Great Dane, Saint Bernard, Afghan Hound, and Cocker Spaniel all have a greater risk of developing an enlarged heart, also known as dilated cardiomyopathy (DCM), as compared to other breeds.

An enlarged heart in dogs develops when the heart’s muscles weaken, causing pressure in the heart’s blood vessels to increase and, in turn, stretching the muscles. Valvular defects, heartbeat abnormalities, tumors, and heartworms can all be behind the initial weakening of the muscles.

When these muscles enlarge, a number of dangers can follow, such as:

1. Heart Murmur / Arrhythmias

Due to the enlarged muscles, the heart’s valves cannot close completely, causing blood to flow backwards, thus creating a murmur. Arrhythmias occur when the electrical impulses of the heart don't work properly, causing an irregular heartbeat. These impulses can be thrown off as the muscles enlarge.

2. Distended Abdomen

A distended abdomen will typically occur when the muscles on the right side of the heart enlarge so much that they fail and fluid begins to build up in the abdomen. This buildup then puts pressure on the diaphragm, causing trouble breathing. You might also notice your dog eating less or occasionally vomiting, both of which can lead to weight loss and malnutrition.

3. Fluid in the Lungs

Fluid in the lungs will typically occur when the muscles in the left side of the heart enlarge so much that they fail, causing fluid to pool in the lungs. This buildup then fills space in the lungs needed to bring oxygen into the bloodstream. In addition to causing a lingering cough, heavy breathing, fatigue, fainting, and even a bluing of the lips or tongue, fluid buildup in the lungs can also result in death.

4. Heart Failure

Congestive heart failure occurs when the heart’s muscles enlarge to a point at which they can no longer meet the circulatory demands of the body, often resulting in death.

Enlarged hearts, if they do develop, normally develop in dogs between 4 to 10 years of age and can be found via a radiograph of the chest. The severity of the condition is determined with an ultrasound, which will show how much muscle function is left. However, your vet may spot the condition during a thorough physical exam.

Depending on how severe the condition is, your vet can prescribe medication to help the heart contract more effectively. They will also schedule regular checkups to track any progress, which can be determined with radiographs, blood pressure measurements, EKGs and biochemical tests.

Unfortunately, in most cases, by the time the condition is spotted and diagnosed it is too late -- life expectancy is usually determined to be under six months. But within those months, your vet can best advise you how to make your dog's life as comfortable as possible.

More on Heart Health

7 Risk Factors for Congestive Heart Failure in Dogs
Nutrition for Cats and Dogs With Heart Disease
Heart Disease in Dogs and Cats

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.


Im sorry to say, there is no need for all that testing. As far as walking your baby, keep them short and try to make the longest walks in early morning or late evening when its coolest. They still need a little bit of exercise, they will slow down and possibly even sit down when they have done all they can.


I think this is great advice that I will also consider since my 10 year old Maltese also was diagnosed with an enlarged heart. So far it is costs me $866 just for blood and x-rays tests and I can only imagine what the cardiologists will charge for the ultrasound...

His illness is fairly recent but I was NOT offered any meds for his heart condition... I am wondering how long my son (pooch) can life with an enlarged heart bc today he seems to be normal. I am scared to take him for a walk bc I don[t want to stress his heart :-(


If your dog is not to the point of passing out when she gets excited, you probably have more time that you think. I had a doberman that was dx with a heart murmur at age ten. All she too was Salix and she lived to be 17. Her primary symptom was coughing. It stopped as soon as she started taking the salix. My next dog with heart failure was a chihuahua. She was given several meds and they didn't work at all. She was twelve and her heart murmur was detected during a well check. she passed out every time she was excited. Then she got thjin and it became unbearable. I had her put down and I regret doing that. It looked so pitiful, but after giving it some thought, she didn't seem to be in pain. I wish I would have let her die at home with me rather than on a cold vet table under bright lights, afraid. The dog I own now, a small chihuahua was dx with a 4/6 murmur during a well check also. She is on vetmedin, enalapril and salix. And she is doing fabulous. I don't know why I have been blessed with these heart challenged babies, but I wouldn't trade the love from them for anything. Just love your baby and be there for him/her as you normally do. Ask your vet if she is in pain. If not, then I strongly suggest you let her pass at home, with you, in the comfort of a familiar, warm place. God bless.


I have a Chihuahua and she has been gagging. She used to do it once in a while but lately it has been much more often so I took her to the vet today and she got an x-ray. The outcome was a very enlarged heart. She was put on medication, a pill called Benazepril. It broke me heart because I wish I would have known and had her checked when she first started gagging, but she is so small I always assumed she had something stuck in her throat that would go down. She is 10 and I know this was not a good diagnosis. I just wonder and wish I would have asked the Dr. if her heart could get smaller with treatment. She is a happy, very loving dog and I always hoped she would live a long, healthy life, but she is already 10. I'm sad, and very worried.

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