Heart Murmurs in Cats
There are several potential causes that can be corrected without surgery

Heart murmurs in cats may show absolutely no symptoms at all in your pet, and in some kittens, they may totally disappear by the time they reach six months old.

However, in some cats they can result in slow, fast, or erratic heart rates that may eventually lead to a severe weakness.

They can affect cats at any age or sex, as well as any breed. The actual long term prognosis for your cat with this condition will all depend on the underlying cause as well as the type of the murmur.


Heart murmurs are auscultatory sounds which are best described as internal sounds in the body that are created by your cat’s heart.

They are created by turbulent or disturbed blood flows through your cat’s heart or vasculature, which is an arrangement or the distribution of blood vessels to an organ or part of their body.

They can generally be heard over any part of your cat’s heart and can have a myriad of potential causes.

Murmurs in your cat may indicate an abnormal heart valve, some type of heart muscle disease, an abnormal opening between the sides of your cat’s heart, anemia, or an abnormal thyroid function.

However, it may also be caused by one of the fastest growing concerns for cat owners worldwide; heart worms.


Each heartbeat in your cat originates as an electrical impulse and will eventually generate a muscular movement in their heart.

Your cats heart is a muscle and it primary job is the pump blood throughout their body.

During this process blood is pumped from the body to the heart, is processed by your cats lungs, and it is returned back to the heart. Once this is completed, it is than pumped back out into the body.

In this process, the blood goes through four different parts of your cat’s heart or heart chambers.

Between these chambers there are valves which are membranes that will open and close in order to prevent the blood from flowing backwards.

Green eyes in catsHeart murmurs in cats only real warning sign is a sudden weakness

Heart murmurs in cats can be the result of a heart muscle or valve that develops some type of abnormality.

If either one of these processes does not function properly, the flow of blood in your cat is disrupted.

This disruption than causes a turbulence to occur in the blood flowing process, and creates an abnormal sound.

This sound is referred to as a heart murmur.


Heart murmurs in cats are classified based on their location in the heart, the timing as well as the duration of the murmur, the character, as well as the grade.

The location refers to the area of the heart in which the murmur or sound originates.

It is in most all cases it can best described by the proximity to a value that could include the aortic or pulmonic valve area.

However, it could also be relative to a body structure that would include the left apex or the sternal border area.

The timing refers to when the actual murmur occurs during the heart beat cycle in your cat. It will be described in one of three ways; systolic, diastolic, or continuous.

The duration of heart murmurs in cats is how long the sound lasts in a registered timing phase.

The character will refer to the quality of the actual sound and is generally rated on two methods; does it get louder or softer during the cycle.

The actual grading process of murmurs is rated on a scale of 1 to 6 where one is the softest and six is the loudest.

If a murmur is quite severe, it may be accompanied by what is referred to as a thrill which suggests that the murmur has become so loud that it can be felt in your cat’s chest wall area.

These classifications help to determine the possible causes.


Heart murmurs in cats are usually only found by listening to your cats heart, unless it has reached the thrill stage.

In this case, you can actually feel it by simply placing your hand on your cat’s heart.

What makes this condition so very challenging, is that some cats will show absolutely no symptoms at all.

However, this is the exception and not the rule.

The first sign or symptom you will see is your cat starting to become weak as well as developing a difficulty in breathing.

If you do see these signs, check their heart rate. If it is fast, very slow, or erratic, they may have a murmur.

Most owners make the mistake of just looking for an erratic heartbeat. However it is not normal and it should be every bit as troubling as an erratic beat.

If the murmur becomes severe enough, your cat may start to collapse.


There are several major potential causes of heart murmurs in cats and many of them can be corrected without surgery.

The first of the causes is hereditary and is a situation where your cat has an abnormality or defect within their heart wall or valves.

This is perhaps the most common form and most kittens will outgrow it within four to six months.

It does not actually affect the heart unless it does not repair itself.

The next potential cause is from severe anemia that is the result of flea or tick infestation.

If this is the cause, nutritional supplements can treat this form of murmur.

The next cause may the narrowing of the outflow area of the pulmonary artery at the exit of the right ventricle area of your cat’s heart.

This is called the pulmonic stenosis, and in this case the murmur is the result of abnormal outgoing turbulence of your cat’s blood meeting resistance.

The outflow area of your cat’s heart, the aortic stenosis, can have the same problem, which is the next potential cause.

A hole in the interior wall of the pumping chambers may also cause a murmur, as well as a leaking valve.

This is referred to as mitral valve dysplasia, and is one of the more common causes.

PDA, which causes your cats blood to shunt may also be the cause, but only if the shunting occurs from the left to right side of the heart.

Hypothyroid disease is another leading cause of heart murmurs in cats.

This disease can easily be treated with medication as well as with surgery.

Feline cardiomyopathy, a heart disease, can also be the cause as it changes the shape of the heart muscles, stretches them, or thickens them.

When this does occur, it reduces the overall effectiveness of the heart which causes murmurs.


Heart murmurs in cats should always be treated seriously, but for the most part they are not life threatening unless they become severe.

Several cats will simply outgrow them, but if they do not, medications and surgery are extremely effective.

The key is to catch murmurs early and is usually done by your veterinarian on an examination. However, you can also watch for the signs yourself.

Pet Medications for Heart Murmurs in Cats

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More Heart Conditions in Cats

Aortic Thromboembolism

Also referred to as saddle thrombus, is a blood clot in your pets system and is a common complication that is associated with heart disease.

Atrial Fibrillation

The symptoms will not be real specific, and as a result, can be very difficult to detect.

Heart Attacks in Cats

Are different than in people simply because they do not experience what is referred to as myocardial infractions.

Heart Worm Disease

It is actually a serious threat in all 50 states and in most countries other than very frigid environments.