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How Long Can a Dog Live With a Heart Murmur?

How Long Can a Dog Live With a Heart Murmur?

If you are considering adopting a puppy with a heart murmur or your dog has just been diagnosed with it, you may be wondering "how long can a dog live with a heart murmur?" The answer is, it depends. The life expectancy of a dog with a heart murmur can vary based on several factors. Many puppies can lead normal healthy lives with heart murmurs, but there can sometimes be underlying heart conditions that can have an impact on a dog's life expectancy. The best option is to consult with a veterinarian, and possibly, follow through with a cardiologist, for the best idea of what to expect.

heart murmur puppy

A Closer Insight

Heart murmurs in dogs are simply abnormal swishing sounds produced by the heart. The best way to describe the sound of a heart murmur is hearing a "lub-swish-dub" sound instead of the normal "lub dub."

A veterinarian will detect these sounds upon listening to the puppy's or dog's heart with a stethoscope.

From the intensity of the murmur, the vet may grade the murmur from a scale of 1 to 6, with one being very soft and 6 being very loud, many times even palpable through the dog's chest wall.

What causes these abnormal heart sounds in dogs? The sound of a heart murmur is caused by turbulent blood flow. In other words, the blood is not flowing smoothly as it should through the chambers of the dog's heart.

The underlying trigger that causes this turbulent heart flow is what is really important to investigate. If your puppy or adult dog was found to have a heart murmur, then investigating the cause of turbulent heart flow is what will provide you with a better idea on whether the heart murmur is something that may have an impact on your dog's life expectancy.

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Hope with Puppies

With puppies, the good news is that there are chances for the murmur to fade and eventually disappear as the heart develops and reaches normal dimensions. Generally, these murmurs tend to disappear once the puppy reaches 3 to 4 months of age and they are in most cases not indicative of heart disease. For this reason, these types of murmurs are often called "innocent murmurs."

Unfortunately, it's impossible to predict with certainty whether a puppy's heart murmur will go away on its own as the puppy develops or whether it will remain. Only assumptions can be made.

Generally, if the murmur is still present once the puppy is 6 months old, then this is a sign that it's not longer an "innocent murmur" and therefore it's time to investigate the underlying cause, explains veterinarian Dr. Marie.  Puppies with a murmur showing signs such as coughing, lethargy, problems breathing, should be evaluated sooner than later.

" Many puppies and kittens have heart murmurs that they outgrow, but usually these are grade 1-2 murmurs."~ Dr. Rebecca, veterinarian

A Heart Ultrasound

dog ultrasound

The best way to investigate the dog's heart murmur is by having the puppy or dog undergo an echocardiogram, also known as an ultrasound of the heart.

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This is the best way to understand the cause of the turbulent heart flow and gain a possible prediction regarding the longevity of the dog's life, explains veterinarian Dr. Andy .

While chest x-rays may show a few things such as possible presence of congenital defects, the ultrasound is helpful in evaluating the dog's heart valves, blood vessels and the overall functioning of the heart.

An ultrasound not only can help pinpoint the source of the murmur, but it can also provide insights into the degree to which the heart is affected.

It's best having the ultrasound done by a veterinary cardiologist. How much does an ultrasound of a dog's heart cost? Generally, expect to pay anywhere in between $300 and $500, but it's best to call around for exact quotes.

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A List of Findings

A heart murmur isn't always a sign of a problem with the heart. In some dogs it may be due to anemia, considering that the blood in anemic dogs tends to be more watery than normal, explains veterinarian Dr. Andrea J Cecur. Because of this, the blood will flow faster through the heart causing a murmur. For this reason, it's important having a complete blood count done so to detect low numbers of red blood cells.

Other causes for heart murmurs include narrowed blood vessels (subarotic stenosis, SAS), abnormal valves (leaky mitral valves), abnormal muscle contractility of the heart, holes in the wall between chambers (atrial septal defect,ASDand abnormal blood flow between the chambers of the heart.

A Word About Puppies

 It is not unusual to find in puppies a condition known as patent ductus arteriosus (PDA). PDA consists of the presence of a channel within the heart that is supposed to close after birth, but that fails to do so. Affected puppies therefore develop a murmur sound that can be heard. Surgical correction is often needed for these pups.


In puppies, the presence of a heart murmur that doesn't go away with age, can be due to congenital disorders. These problems may be corrected surgically, but things can get costly.

Surgery to fix a patent ductus arteriosus may roughly range between $2,000 to $3,000 depending on location. Sometimes, the breeder may help with the costs. It is best to call around for better estimates. Sometimes rescue organizations can help. The good news is that, although priced, surgical intervention results in great improvement and usually completely corrects the problem, explains veterinarian Dr. Gene. 

If you have purchased a puppy from a reputable breeder offering health guarantees, you may be able to to return or exchange the puppy, which is an option, unless you have become attached to the pup.

 If you decide to keep the puppy and don't feel like having an ultrasound done, it may be advisable to shop around and purchase a good pet insurance so to have coverage for any necessary diagnostics and treatments associated with the heart murmur.

"Many dogs will live good long healthy lives with a Grade 2 murmur and never have a problem. However, there is a very small chance that this could be a significant heart problem."~ Dr. Marie, veterinarian

The Bottom Line

There are many dogs who have a heart murmur their whole lives and never develop any problems with it, explains Critical Care Vet. But, of course, this is just the brightest scenario. There may be cases in which things unfortunately do not go so well. Life expectancy in a dog with a heart murmur will therefore tend to vary based on the underlying cause.

If worse, comes to worse, a heart murmur can progress into heart failure and the affected dog will develop coughing and exercise intolerance. Dogs who progress to this stage though are often still capable of leading long and happy lives courtesy of heart medications, but it's difficult to predict for how long, as this is different for each dog, explains veterinarian Dr. Dan. 

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