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

by Veronique Fournier October 18, 2021 6 min read

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


You will probably agree with me if I tell you that the heart is one of the most important organs in the body! It’s the engine of our machine, the pump that circulates the blood in our body and is therefore responsible for the efficient transport of the oxygen that we breathe to the cells of our body.


Animals, just like us, can have what is called a heart murmur. As the name suggests, it's a subtle noise that is heard between heartbeats. It sounds a bit like wind and is audible only with a stethoscope, of course.


By reading this article, you will learn more about what causes a heart murmur in cats. I will also describe the life expectancy of a cat with a heart murmur as well as the symptoms, grades and 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. Each case is different, of course, but it’s my pleasure to share my experiences here with you.


Read on to learn more about heart murmurs in cats.



What is a heart murmur in cats?


A heart murmur is actually the sound of vibrations, caused by the turbulent flow of blood through the valves and vessels of the heart.


A heart murmur can be associated with an anatomical abnormality of the heart (pathological heart murmur), but in cats, a high percentage of them who have a heart murmur do not have a structural abnormality of the heart as such. We then get into the case of physiological heart murmurs.


It’s very difficult to diagnose heart disease simply by auscultation of the heart by a vet (i.e. using a stethoscope). The location of the murmur and its grade can certainly provide a clue, but more investigation is often needed to make a diagnosis of heart disease.


To make it more complicated for our vets, some animals can even suffer from heart disease without having a heart murmur.



What causes a heart murmur in cats?


As mentioned above, there are pathological heart murmurs and physiological heart murmurs. Pathological murmurs are directly related to a deformation of a structure of the cat’s heart, while physiological 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. The cat breed the most affected by this disease is the short-haired domestic cat.


Other heart conditions can also be present in our kitties, either from birth or developing later, but these are less common. A murmur also doesn't always mean heart disease is present. Read on to understand.


The physiological heart murmur


This type of murmur can occur at any age in cats. A physiological murmur may be secondary to a disease such as hypertension, hyperthyroidism, anemia, or can simply be “innocent”.


I have often heard of the “innocent” heart murmur in young kittens during their first vet exam. It is named like this because it is quite common and of no consequence. 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; a sort of hiss or murmur.


In addition, 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.



The different grades of heart murmurs in cats


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.



Symptoms of a heart murmur in cats


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 such as hypertrophic cardiomyopathy, these are the heart murmur in cats symptoms to watch out for:

  • Increased respiratory rate
  • Loss of appetite
  • Respiratory distress
  • Cough


It should be noted that cats hide their illnesses very well and may not show any signs!



Heart murmur in cats: life expectancy


The life expectancy of a cat with a heart murmur varies depending on the nature of the heart murmur, ranging from a few months to a few years. If, for example, 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 condition.


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.


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


For cats who only have a mild hypertrophy, the life expectancy 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.



Treatments for heart murmurs in cats


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 hypertension, hyperthyroidism, or anemia can be controlled by treating the condition first. For structural heart disease, 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, to treat secondary congestive heart failure and to 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.

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Instead of struggling through in-person appointments and waiting rooms, our consultations are 100% online via email and video call.

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Does your cat have a heart murmur? Do you know the cause? Share their story with us in the comments below.


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Veronique Fournier
Veronique Fournier

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