Heart Murmurs: Why are Cavaliers Prone to Getting Them

Heart murmurs are common in all dog breeds and are not always a sign of something more sinister than a simple heart murmur. But statistically, a Cavalier King Charles Spaniel is more likely to suffer from a heart murmur than other dog breeds, but why is this?

Heart murmurs are hereditary in Cavalier King Charles Spaniels, and are the precursor to Degenerative Mitral Valve Disease (MVD), which is the leading cause of death within the Cavalier breed.

So heart murmurs can be the beginning of Mitral Valve Disease, and MVD is highly-heritable within Cavaliers, but what actually are heart murmurs and MVD, and what do we do to prevent our beautiful Cavaliers from suffering from them? Read on for an in-depth look at heart murmurs.

What is a Heart Murmur

A heart murmur is defined as an extra or unusual sound in your heartbeat. This distinctive sound can be heard through a stethoscope and is often referred to as a swishing or whooshing sound.

This noise is heard when the blood being pumped through the heart is not moving correctly. In humans, this is usually nothing to worry about, but I would still advise seeking medical guidance, just to be on the safe side.

However, with Cavalier King Charles Spaniels visiting your local veterinarian is a must. As discussed earlier, a heart murmur could be an early sign of Mitral Valve Disease.

What Causes Heart Murmurs

In Cavaliers, the primary factor is inheriting the condition from their parents, and as a result, it affects over half of Cavalier King Charles Spaniels by the age of 5 years old and over 90% of Cavaliers aged 10 years old and above.

Other factors that can cause a heart murmur are excessive weight, lack of exercise, and rapid weight gain.

Obviously excessive weight and lack of exercise go hand in hand, but this is not only the reason for weight gain. Your Cavalier could have an overactive thyroid or some other medical issue that must be diagnosed by a veterinarian.

Remember that too much exercise can also be detrimental to your Cavaliers’ health, 2 to 3 short walks a day are recommended over one enormous walk, as this too can cause problems due to the over-exertion on their heart.

Why do Cavaliers get heart murmurs?

Bad breeding holds a very significant link in the reason that Cavaliers are prone to heart murmurs, as the precursor to the more severe Mitral Valve Disease (MVD) is a heart murmur.

Breeders that are just in it for the money (in particular puppy farmers) don’t care about the animals’ health and well-being, so they will have no problems breeding with Cavaliers that are already suffering from MVD.

As this is a hereditary disease, you can almost guarantee that the puppies from those parents will also suffer and possibly die from MVD during their short lives.

If this type of breeding continues, then the cycle can never be broken, and Cavaliers lovers worldwide will be heartbroken at some stage when they lose their best friends.


  • MVD affects 50% of Cavaliers by the age of 5 and almost all Cavaliers by the age of 10
  • Cavaliers are 20 times more prevalent to MVD than any other breed of dog
  • MVD is the most common form of heart disease in older dogs
  • There is NO cure for MVD
  • More males develop MVD than females

How do you know if your Cavalier has a heart murmur

A regular check-up with your veterinarian is a must from an early age (around 1-year-old). During these regular checks, the vet will check and listen to your Cavalier’s heart for the sounds of a tubulent blood flow with a stethoscope.

Do all Cavalier King Charles have heart issues

Not all Cavaliers have heart issues initially, but there is a very high probability that they will have them later in life. So it is vital to have regular heart checks to see if/when they begin.

If heart problems are detected and you are planning on breeding from your Cavalier, then you may want to re-think the idea. Breeding from a Cavalier with a weak heart will only exacerbate the issue, so we need to think about the long-term rather than the short.

Preventing a Heart Murmur

You can build a strong, healthy heart with the correct diet and regular exercise (ideally 2 to 3 smaller walks a day rather than one big walk) to try and combat a heart murmur, but if your Cavalier has developed MVD, this is incurable.

As the disease is genetic it will be passed to your Cavalier if their parents suffered from the disease, but there is a glimmer of hope for future breeds of Cavaliers, by adhering to the MVD breeding protocol.

The MVD Breeding Protocol

The Mitral Valve Disease breeding protocol has been designed to try and eradicate the disease from not only Cavalier King Charles Spaniels, but all breeds of dog.

In brief, it tries to prevent this hereditary from being passed on to future generations, thus ending it almost entirely in the future.

Here are the steps outlined to breeders:

  • Every breeding Cavalier King Charles Spaniel should be examined annually by a board-certified veterinary cardiologist
  • Do not breed with any Cavalier who is diagnosed with an MVD heart murmur under the age of 5 years
  • Do not breed with any Cavalier before 2.5 years
  • Do not breed with any Cavalier under the age of 5 years, unless its parents’ hearts were free of MVD murmurs by the age of 5 years

By following these guidelines breeders will ensure the health of all future Cavalier puppies.

How long can a Cavalier live with a heart murmur?

This is a very difficult question to answer as not all Cavaliers are the same, some will live longer lives than others depending on various factors.

Our Cavalier, Lady, was diagnosed with a very slight heart murmur around the age of 1-year-old, and I am very thankful to say that the condition hasn’t worsened over time.

She is almost 11 years old now, and we still have regular checks on her heart to ensure it hasn’t worsened in any way. The reason for the regular checks is to catch it before it gets too bad. If caught in time there is medication that your Cavalier can take to assist, and can lengthen their lifetime.

Luckily Lady doesn’t need any medication, which can only be a good thing.


Although a heart murmur can move to more problematic heart conditions, this may not be the case. Try to keep your Cavaliers heart fit and healthy with good nutrition and regular exercise.

This coupled with regulated breeding will be helping Cavaliers to live a long and happy life in the future.

Medical Terms

When talking to medical professionals, including veterinarians, about heart disease or disorders there are usually a few medical terms that are thrown about. To assist I have put the definition of these terms below.

Heart Failure

Heart failure is defined as the heart still working but it is failing to successfully pump blood around the body.

The symptoms of heart failure include:

  • High rates of breathing
  • Exercise intolerance
  • Shortness of breath
  • Increase in respiratory effort
  • Fainting

Congestive Heart Failure 

Congestive Heart Failure occurs when the heart dysfunctions and increases blood pressure, which in turn causes a fluid buildup in the lungs.


For more in-depth knowledge of heart murmurs and Mitral Valve Disease in Cavalier King Charles Spaniels, please refer to the sources of my information.

3 thoughts on “Heart Murmurs: Why are Cavaliers Prone to Getting Them”

  1. Pingback: Hip Dysplasia: Is Your Cavalier Likely To Get It – My Cavvy
  2. Pingback: 9 Diagnosed Common Genetic Defects in a Cavalier | My Cavvy
  3. Pingback: What Foods Can a Cavalier King Charles Spaniel Eat? | My Cavvy

Leave a comment