Heart murmurs in Cats

cat heart murmur

Dr. Swindell listening to a patient’s heart.

During an examination we sometimes detect a heart murmur in a cat, but this finding is not always cause for immediate concern. During an exam we have two primary goals:

  • Identify any issues
  • Educate you as a pet caretaker

We want to make certain that you understand what having a heart murmur, or any of your pet’s medical conditions, mean.  Having and understanding this information will then help you to make educated decisions about your cat’s care.

Scoring a cat’s heart murmur

You have seen us use our stethoscope every time you have brought your pet in for a check-up or visit. When we listen with our stethoscope to a cat’s heart we can pick up subtleties in the sounds. So when we hear a heart murmur in a cat we are assessing loudness, pitch, and in which stage of the heart beat the murmur is occurring.

Veterinarians always grade a heart murmur. We use a 1-6 scale to grade the loudness of a murmur, therefore we have something objective we can track over time. Grade 1 is hardly audible with a stethoscope, while grade 6 is not only audible with our stethoscope, but is also palpable with a hand on the outside of the chest. There is no defined rule that a heart murmur will get louder as the disease affecting the heart progresses, but it often will.

The goal is to identify the cause of the cat’s heart murmur

A heart murmur in a cat is not a diagnosis in itself.

It is a manifestation of a disorder of the heart or the blood vessels.  We make the diagnosis through further investigation into the cause of the murmur.  The simple definition of a heart murmur is turbulence of blood flow through the valves of the heart. There are 4 main valves in the heart. The blood flows at high speeds through these valves in one direction only. Anytime there is some regurgitation of blood through a valve in the opposite direction we can hear the turbulence of the blood flow as a slight “wooshing” sound, called a murmur.

The ‘lub’ and “dub’ sounds of a cat’s heart

The physiology of the heart is very similar across many species of mammals; a cat’s heart is very similar to our own human heart. There are two main heart sounds in a heartbeat. A ‘lub’-when the blood is ejected from the heart into either the lungs or the aorta before being delivered all over the body.  And a ‘dub’- when the heart fills with blood and the valves to the ‘exits’ of the heart are closed.

Dopper to analyze a pet's heart murmur

Doppler image of blood flow in a pet’s heart.

While there are many causes of heart murmurs in cats there are some more common causes in the species.  High blood pressure (or hypertension) is common, especially in older cats. Also, an overactive thyroid (Hyperthyroidism) can affect the heart in a few ways; it can increase the heart rate, thus the flow and velocity of blood through the heart, and it can cause a high blood pressure, and change the heart muscle by making it do more work. Hyperthyroidism tends to also affect older cats (9 years old or older).  Disorders of the heart itself include enlargement of the heart chamber muscles (hypertrophic cardiomyopathy), degeneration of the heart valves as a cat ages, and a systemic (whole body) infection that can subsequently infect the heart valves themselves (endocarditis). Heartworm disease

(Blog post on heartworm disease), of course can also cause heart murmurs.

So you see, there are diseases that originate elsewhere in the body that affect the heart in various ways. Because of this, one of the most important tools we have for diagnosing the cause of a heart murmur in a cat is general blood-work. Of course we’ll recommend x-rays and blood pressure to help us diagnose heart problems as needed.

A Veterinary Cardiologist often makes the final diagnosis about a cat’s heart murmur

echo-cardiogram of a pet's heart with a murmur

Echocardiogram of a pet’s heart with valves labeled.

We have the benefit of having a Board Certified Veterinary Cardiologist as a part of our team at Carlson Animal Hospital, so often the final step to a final diagnosis is a visit with her for an ultrasound of the heart.

This is called an Echocardiogram, and will provide just about everything we need to know about the inside of the heart and its full functionality.

With the diagnostic information complete, we can then provide you and your pet with a diagnosis, prognosis, and treatment options. We can also use this information to make patient-specific anesthesia plans that are as safe as possible for surgeries or dental cleanings. Often, no matter the diagnosis, cats can live happy years with heart disease with your good care and ours.

Always our goal is to provide the best and most comprehensive medical care possible for your pet and the best education for you.

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