My cat has a heart murmur: what does this mean? Can I treat it naturally?

Authored byVeronic Fournier

Cats can have what is called a feline heart murmur. It's a subtle abnormal heart sound that is heard between the heartbeats of a fully conscious cat. A clinically significant heart murmur is audible only with a stethoscope.

This article is all about the important things to know about heart murmurs in cats. I will also describe the life expectancy of a cat with a heart murmur as well as the symptoms, grades, as well as possible treatments for a heart murmur.

As an animal health technician, I have heard heart murmurs on several occasions when taking vital signs for dogs and cats during their vet exam. While there are innocent heart murmurs, there are also those that could be signs of acquired heart disease and may be detrimental to your cat's health.

Each case is different, of course, but it’s my pleasure to share my experiences here with you.


A Quick Primer on Heart Murmur in Cats

Cat licking its paws.

Heart murmurs in cats are caused by the turbulent flow of blood through the valves and vessels of the heart. While a heart murmur generally implies turbulent blood flow, it may also mean other factors like relatively small defects in the heart structure like narrow heart valves.

A heart murmur can be associated with an anatomical abnormality of the heart (pathological heart murmur). However, in the context of felines, a high percentage of them who have a heart murmur do not have an underlying heart disease or some issue with the heart muscle.


Physiological heart murmurs

It’s very difficult to diagnose heart disease simply by auscultation (or using a stethoscope) of the heart by a vet.

The location of the heart murmur in cats and its grade can certainly provide a clue, but more investigation is often needed—like a detailed ultrasound examination—to make a diagnosis of the cardiac abnormality or severe heart disease like restrictive cardiomyopathy.

To make it even more complicated, some animals can even suffer from heart disease without having a heart murmur. Besides cardiac ultrasound examination, a periodic examination should also be considered in this case.


Causes of Heart Murmurs in Cats

A cat sitting.

Just to reiterate, there are pathological heart murmurs and physiological heart murmurs in cats.

First, pathological heart murmurs are directly related to a deformation of the structure of the heart (such as in the case of physical problems with the pulmonary artery or ventricular septal defects) or even an incidental finding of stunted growth.

On the other hand, physiological heart murmurs can be the consequence of a multitude of physiological processes.


Pathological heart murmur

The most common structural heart disease in cats that typically results in a heart murmur is hypertrophic cardiomyopathy. To give you a very crude definition of this disease, the muscles of the cat's heart thicken, which makes it harder to expel blood from its vessels as the heart can no longer contract or relax normally.

A genetic cause of this disease is suspected. Indeed, several genetic mutations have been identified as being responsible for the development of this disease. Short-haired domestic cats are commonly affected by this health issue.

Other heart conditions can also be present that lead to intermittent heart murmur, either from birth or developing later, but these are less common. Remember, a murmur (even quite loud murmurs) doesn't always mean cardiac disease is present.  


Physiological heart murmur

A physiologic murmur can occur at any age in cats, even among healthy adult cats.

A physiological murmur may be secondary to a disease such as systemic hypertension, hyperthyroidism, or anemia—or can simply be "innocent." I have often heard of the innocent heart murmur in young kittens during their first vet exam.

It got its name because it is quite common and of no consequence. They're also referred to as "benign murmurs." Due to their small size (and therefore the small size of their blood vessels), blood is pumped by the kitten's heart at high speed in a very small space which creates a mechanical noise.

It is the turbulent blood flow within the heart chambers making the abnormal noise that is being heard in this case. Blood flow from large vessels exiting can sometimes create strange heart sounds.

Young kittens are often stressed during their first vet check-up, so their heart rate is elevated. The volume of blood being pumped is therefore greater, which increases the chances of hearing such a murmur. This type of heart murmur usually goes away on its own around 5 months of age.


Different Grades of Heart Murmurs in Cats

Cat looking at the camera.

The murmur intensity is usually rated with a grade between 1 and 6, with 1 being the most subtle and 6 being the most severe. This grade can serve as a benchmark against which to assess the severity of heart disease if it occurs, but several factors should be considered in the diagnosis.

To differentiate a grade 2 from a grade 3 or grade 4 heart murmur, the vet must have a good ear, as they can be difficult to evaluate. Only an echocardiogram can determine if your beloved cat's prognosis only involves innocent heart murmurs (or incidental heart murmurs) or perhaps one that involves an underlying heart condition.

Blood tests may also be conducted to examine certain criteria (i.e. checking for a leaky heart valve and other clinical signs) and achieve a reasonable result based on this grading system, especially among older cats.


Common Symptoms of a Heart Murmur in Cats and Related Clinical Signs

Cat sleeping on the bed.

You will probably understand that the symptoms of feline heart murmurs vary depending on the cause. An innocent murmur will have no symptoms. A hyperthyroid cat with a murmur will be more active than normal, lose weight, and have a dull coat. A cat with a murmur caused by anemia will have pale mucous membranes.

For pathologic murmurs caused by structural heart disease, these are the heart murmur in cats symptoms to watch out for:

  • Increased respiratory rate and breathing problems

  • Loss of appetite or poor appetite

  • Respiratory distress

  • Cough

  • Pale gums (as in the case of functional heart murmur)

  • Sudden weight loss

It should be noted that cats hide their illnesses very well and may not show any signs since it is completely painless!


How Long Do Felines With Heart Murmur in Cats Live?

Sitting ginger tabby cat.

The life expectancy of a kitty with a heart murmur in cats varies depending on the nature of the heart murmur, ranging from a few months to a few years. For example, if your cat is suffering from a heart murmur related to hyperthyroidism, treatment for this primary concern can help resolve some or all of the associated heart conditions.


Severe heart disease can be a key factor

If your cat has hypertrophic cardiomyopathy, its life expectancy also depends on several factors. However, there is no cure for this, only supportive treatments. The prognosis is therefore less favorable to your cat's health.

This heart disease can progress rapidly over a few months, while for other cats it can develop slowly over several years. It is difficult to give a precise estimate. Some cats who have no symptoms may also die suddenly from this disease, particularly among older cats.

For cats who only have mild hypertrophy, it can be several years. When the disease is more severe, the risk of developing congestive heart failure is higher and the prognosis is poorer. At this point, the life expectancy is between 12 and 18 months.

There is also the less common risk of thromboembolism, secondary to this disease. This is the formation of a clot which often presents with paralysis of the hind legs. The prognosis for this complication is also bleak.

Remember that common symptoms of cardiac issues include unexpected weight loss, poor appetite, and pale gums. Sure these "other signs" may not necessarily relate to heart issues to blood flow from large vessels exiting forcefully, but they may result in a more severe murmur if overlooked.

Never ignore these thinking that they'll no longer present sooner or later!


Treatments for Heart Murmurs in Cats

A gray cat.

As discussed above, one must first question the cause of the heart murmur. For an innocent physiological murmur, there is nothing to do, it should fade over time. A murmur caused by an underlying cause like hypertension, hyperthyroidism, or anemia can be controlled by treating the condition first. For structural heart disease, such as a ventricular septal defect, the treatments are more complex.

There is no cure for hypertrophic cardiomyopathy. However, some medications can be tried to improve life expectancy and quality of life. I am thinking of medications to relax the heart muscles, treat secondary congestive heart failure, and prevent blood clots from forming and therefore reduce the risk of thromboembolism.


Online Homeopathic Consultation

Our Online Homeopathic Consultation is just what you need if you want to take care of your cat's heart murmur naturally.

Zumalka provides a personalized solution to target the root of your pet's problem, instead of just the symptoms. And all of this is done in the comfort of your own home!

Instead of struggling through in-person appointments and waiting rooms, our consultations are 100% online via email and video call. It's a real conversation with a real homeopath about your pet—without all the hassle and miscommunication.


About the author

Veronic Fournier
Veronic Fournier


Véronique Fournier shares her extensive pet health know-how on Zumalka through her articles.

Véronique’s background as an animal wellness advocate began in Cégep La Pocatière in Quebec, which led to comprehensive internships and training with respect to the breeding, rehabilitation, and monitoring of various types of animals. The institutions she has worked with include the Quebec Aquarium and the SOS Miss Dolittle shelter, just to name a few.

Her immersion with various veterinary clinics in British Columbia and other places has made Veronique not just knowledgeable, but also quite perceptive in zeroing in on the right strategy to help keep pets in the best of health.

And can we get you in on a secret? Veronique shares that she has already made a lot of canine pals due to her stint as a foster mom in several shelters. Isn’t that cool?

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