Heart Murmur In Cats: Causes, Symptoms, Treatment

A heart murmur is a dysfunction of the heart that produces abnormal sounds from this organ. This sound being almost inaudible by the owner of the cat, it is most often the veterinarian who detects this anomaly during a consultation.

The possible origins of this disorder are many and varied, but current medical means allow it to be better understood.

What are the symptoms of this heart problem, and how to spot it quickly? What are the possible medical interventions to slow down its progression?

What is a heart murmur?

Heart murmur is not strictly speaking a disease. Rather, it is the audible expression of a heart problem, which is in addition to the classic beating of the heart

In cats, the normal heart rate is between 120 and 140 beats per minute. Beyond 180 beats per minute, the veterinarian should be concerned.

These additional beats that can be heard through a stethoscope indeed testify to an abnormal blood flow in the heart, and therefore to the dysfunction of the organ. The audibility of blood flow superimposed on the normal flow of the heart is considered abnormal; this is a pathology that requires immediate treatment by the veterinarian as soon as he/she perceives this dysfunction. Even if the intensity is low, tests will determine if it is heart disease.

Heart murmur is classified into six categories depending on its level of intensity:

  1. A slight sound almost undetectable with a stethoscope;
  2. A soft breath detectable with a stethoscope during a routine examination at the veterinarian;
  3. A sound of moderate-intensity, easily detectable with a stethoscope;
  4. A loud breath, very easily audible with a stethoscope;
  5. A sound of even greater intensity than the previous one;
  6. A very sonorous breath, immediately audible in the ear or in contact with the hand.

In addition to the sound level, other criteria characterize the heart murmur. The veterinarian thus takes into account the regularity or discontinuity of the sound, the tone (bass or treble), the sound envelope (crescendo / decrescendo) as well as its strongest point of intensity.

What are the possible causes of a heart murmur?

The possible causes of a heart murmur in cats are very numerous.

In kittens, a congenital heart defect is often the cause of the problem: the heart murmur is then the sign of a genetic and hereditary disease.

In adult cats, heart diseases are more often acquired, such as dilated cardiomyopathy.

However, other factors can be at the origin of this heart disorder:

  • anemia
  • arterial hypertension
  • hyperthyroidism
  • renal failure ;
  • bacterial endocarditis

Are some cats predisposed to heart problems?

The age of the cat is an important criterion to take into account when detecting a heart murmur.

Indeed, in a young cat, this anomaly is surely due to a congenital disease, while in an older cat, it more likely reflects a heart disease that developed naturally.

The breed of the cat is also an important point, because certain breeds related to the Persian (such as the Maine Coon , the Ragdoll, the Sphinx, the British Shorthair, the American Shorthair, or even the Bengal ) are more predisposed to hypertrophic cardiomyopathy (CMH ) , the most common heart disease in cats.

It consists of a thickening of the wall of the heart muscle which causes a decrease in the volume of the chambers of the heart, also called heart failure.

The feline hypertrophic cardiomyopathy usually begins between 5 and 7 years. In Ragdolls and Maine Coons, genetic tests can be carried out in the kitten’s first months to detect an anomaly.

These tests make it possible to define the risk of hereditary transmission of the disease, in particular before considering the reproduction of the cat. On the other hand, for other breeds of cats, no DNA test is yet available to detect hereditary hypertrophic cardiomyopathy.

What are the symptoms of cardiac dysfunction in cats?

The heart murmur is only audible with a stethoscope and is therefore very difficult for the cat owner to detect.

However, it may be just one symptom of other symptoms that can also warn of a heart problem, such as:

  • a cat stunting
  • a weight loss visible
  • of breathing difficulties (shortness of breath, wheezing …)
  • a recurrent cat cough
  • paralysis of the rear limbs
  • a pronounced state of fatigue

These symptoms are sufficient signals to prompt the owner to make an appointment with a veterinarian. A stethoscope examination will detect a heart murmur and make a first diagnosis.

To deepen the diagnosis, other modern exams like ultrasound, electrocardiogram, or blood tests can be done to identify the exact cause of this heart dysfunction.

Heart Murmur In Cats: Causes, Symptoms, Treatment

Can we cure a heart murmur?

Sometimes the kitten’s breathing is strong and audible during the first weeks of its life and then decreases as it grows until it disappears completely after a few months.

However, when a heart murmur is audible in an adult cat, surgery or drug treatment may be considered, depending on the cause of this heart dysfunction.

Medical treatments are of real interest because they bring comfort to the cat and reduce the risk of complications. Thus, diuretics help the cat cope with congestion problems and improve breathing, while other treatments aimed at treating hyperthyroidism and hypertension in cats help to combat the thickening of the flows.

On the other hand, hypertrophic cardiomyopathy in cats is incurable: to date, no treatment has been proven and allowed the survival of the animal. On average, early diagnosis and immediate initiation of treatment can extend its lifespan by around 5 years. On the contrary, in case of diagnosis and/or late treatment, the life expectancy of the cat is much shorter, hardly exceeding a few months.

However, certain habits can improve the living conditions of a cat with heart disease and help extend the cat’s life expectancy.

In the first place, it is recommended to favor foods with a low salt content: this helps to reduce the accumulation of fluids in the heart and allows it to function more efficiently.

For a cat suffering from cardiac dysfunction, the quality of the environment is also very important: a healthy, calm, and soothing living environment reduces the stress of the cat.

Finally, temperature changes should be avoided as much as possible.

 Final Thoughts

The majority of cats with heart disease do not have symptoms that are easily visible or audible to the owner. As a result, when the diagnosis is made, the disease is often already at an advanced stage.

Even if your companion is apparently in good health, regular follow-up with the veterinarian – in particular through the annual check-up of the cat – makes it possible to detect possible heart diseases as early as possible, in particular through the appearance of a heart murmur.


Finally, thinking about insuring your cat can prove to be saving, because the interventions and / or treatments that these diseases can require are often very expensive.

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