What is a Heart Murmur?

When your dog or cat visits the veterinarian, the doctor will use a stethoscope to listen to the heart. While a regular heartbeat has a certain rhythm, an irregular heartbeat breaks that rhythm either with an extra beat or two, or a “whooshing” sound.

An irregular heartbeat or unusual sound could mean your pet has a heart murmur.

Before you panic, know that there are many different types of heart murmurs, and it doesn’t necessarily mean your pet is in danger. Some animals are born with them, while others develop through the dog or cat’s life. If caught early, they can be managed.

Once your veterinarian realizes there’s a murmur, then they’re going to look for other symptoms to pinpoint the source.

Three Types of Heart Murmurs

If you’ve ever listened to a heartbeat, you know that it has a rhythm. Thump, thump, thump, it goes. You can time it. But a heart murmur is different. It interrupts that regular beat.

As you know, the heart is the muscle responsible for pumping blood through the body. Blood carries oxygen and nutrients to all parts of the body and when it’s interrupted, like with a heart murmur, then you’ll want to find out why.

A heart murmur can slow down the blood flow or cause it to be irregular. Here are the three different types of heart murmurs:

  1. Systolic – murmur occurs when the heart contracts
  2. Diastolic – occurs in between beats
  3. Continuous – occurs throughout

These are based on timing.

 A graphic of a stethoscope

Once your veterinarian hears a murmur, they’re going to listen closer to fit it into one of these categories. They may also grade it on a scale of loudness. Some heart murmurs are so quiet you can only hear them with a stethoscope while with others you may be able to hear while simply hanging out with your pet.

Important Characteristics of a Heart Murmur

Besides the timing and how loud the sound is, your veterinarian will want to determine where the sound is coming from. Combined with the age and other health factors of your dog or cat, knowing if the sound is coming from the left or right can offer more insight.

For example, older dogs with a murmur coming from the lower left of the chest may have degenerative mitral valve disease. Murmurs that can be heard in the neck can be a symptom of aortic stenosis.

Heart murmurs can cause unusual vibrations, disruptions to the blood flow, and even blockages, though it can be tricky to pinpoint where the sound is coming from. Plus, that isn’t enough to information to make a diagnosis. Your veterinarian will look at other factors like the age of your pet and any other symptoms to help.

Puppies can be born with a heart murmur that disappears within the first few months. This is called a congenital murmur. But as dogs age, they sometimes develop heart disease, and a heart murmur can be a symptom. These are called “acquired” murmurs.

What Can You Do About Heart Murmurs?

There is no treatment for a heart murmur specifically. The treatment, if there is to be any, is around other symptoms and health conditions of your pet. Some veterinarians may recommend chest x-rays to better determine the heart’s condition. But it’s all on a case-by-case basis.

Are Some Breeds More Susceptible Than Others?

Some breeds are more susceptible to heart murmurs and heart conditions. King Charles Cavalier Spaniels and toy poodles are at risk for degenerative mitral valve disease. This heart condition enlarges the heart because the blood flows backward. It can lead to coughing and lack of interest in exercising.

Dachshunds are at risk for developing leaky valves. This can usually be controlled by medication and a healthy weight.

A graphic of a cat and dog silhouette

It’s not just small dogs either. Boxers and golden retrievers are at risk, too. Additionally, Maine Coone, Siamese, and Persian cats may be susceptible to a condition called hypertrophic cardiomyopathy.

As you can see, there’s no conclusive treatment for heart murmurs specifically. Your veterinarian will work out an individual treatment plan for your dog or cat.

It’s important to see your veterinarian regularly to keep an eye on your pet’s heart health. We recommend an annual wellness visit once a year prior to five years of age, and we often recommend twice a year visits after that, because pets age faster than humans and a lot can happen in six months.

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