Heart murmur in cats - Causes, symptoms and treatment

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Our little felines, although they seem to be as usual when it comes to health, it may happen that they are diagnosed with a heart murmur in a routine check-up at the veterinary center. Murmurs can be different grades and types, the most serious being those that can be heard even without putting the stethoscope on the feline's thoracic wall. Heart murmurs can be accompanied by serious clinical signs and can indicate a serious cardiovascular or extravascular health problem that causes those consequences in the cardiac flow responsible for that abnormal sound on auscultation of a heart sound.

Keep reading this informative AnimalWised article to learn more about the heart murmur in cats, its causes, symptoms and treatment.

You may also be interested in: Heart murmur in dogs - Symptoms and treatment Index
  1. What is a heart murmur?
  2. Causes of heart murmur in cats
  3. Symptoms of a heart murmur in cats
  4. Diagnosis of a heart murmur in cats
  5. Treatment of a heart murmur in cats

What is a heart murmur?

A heart murmur is produced by a turbulent flow within the heart or large blood vessels leaving the heart, causing an abnormal noise that can be detected on cardiac auscultation with a stethoscope and that can interfere with normal "lub" sounds (opening of the aortic and pulmonary valves and closing of the atrioventricular valves) and "dup " (opening of the atrioventricular valves and closing of the aortic and pulmonary valves) during one beat.

Types of heart murmurs in cats

Heart murmurs can be systolic (during ventricular contraction) or diastolic (during ventricular relaxation) and can be classified according to the following criteria in different degrees:

  • Grade I: audible in a certain area somewhat difficult to hear.
  • Grade II: audible quickly, but less loud than heart sounds.
  • Grade III: immediately audible at the same loudness as heart sounds.
  • Grade IV: immediately audible louder than heart sounds.
  • Grade V- easily audible even when only approaching the chest wall.
  • Grade VI: very audible, even with the stethoscope away from the chest wall.

The degree of the murmur is not always related to the severity of the heart disease, since some serious pathologies of the heart do not produce any type of murmur.

Causes of heart murmur in cats

Various disorders that can affect felines could cause a heart murmur and are as follows:

  • Anemia.
  • Lymphoma.
  • Congenital heart disease such as ventricular septum defect, patent ductus arteriosus, or pulmonary stenosis.
  • Primary cardiomyopathy such as hypertrophic cardiomyopathy.
  • Secondary cardiomyopathy such as that produced by hyperthyroidism or hypertension.
  • Dirofilariosis or heartworm disease.
  • Myocarditis.
  • Endomyocarditis.

Symptoms of a heart murmur in cats

When the heart murmur in a cat becomes symptomatic or causes Clinical signs, may appear:

  • Lethargy.
  • Shortness of breath.
  • Anorexy.
  • Ascites.
  • Edema.
  • Cyanosis (bluish skin and mucous membranes).
  • Vomiting.
  • Cachexia (extreme malnutrition).
  • Collapse.
  • Syncope.
  • Paralysis or paralysis of the extremities.
  • Cough.

When a heart murmur is detected in cats, its importance must be determined. Up to 44% of apparently healthy cats present murmurs on cardiac auscultation, at rest, or appear when the cat's heart rate increases. Between 22% and 88% of this percentage of cats with murmurs without symptoms, a cardiomyopathy or congenital heart disease is detected with a dynamic obstruction of the outflow tract of the heart. For all these reasons, conducting periodic checks is so important, as well as go to the vet in case you notice any of the symptoms of a cat with heart disease.

Diagnosis of a heart murmur in cats

The diagnosis of a heart murmur is made by cardiac auscultation, through the use of a stethoscope or stethoscope in the place of the feline thorax where the heart is located. If a so-called "galloping" sound is detected on auscultation because of its similarity to the sound of galloping a horse or an arrhythmia in addition to the murmur, they are often associated with significant heart disease and should be investigated thoroughly, undergoing a full evaluation with the cat stable, that is, if it presented pleural effusion and the fluid has already been drained.

In cases of murmurs, tests should always be carried out to detect cardiac or extracardiac disease that has consequences on the heart, so that the following can be performed diagnostic tests:

  • Chest x-rays to evaluate the heart, its vessels, and the lungs.
  • Echocardiography or ultrasound of the heart, to assess the condition of the heart chambers (atria and ventricles), the thickness of the heart wall, and blood flow rates.
  • Biomarkers of heart disease such as troponins or pro-brain natriuretic peptide (Pro-BNP) in cats with signs suggesting hypertrophic cardiomyopathy and echocardiography cannot be performed.
  • Blood analysis and biochemistry with measurement of total T4 for the diagnosis of hyperthyroidism, especially in cats older than 7 years.
  • Heartworm Screening Tests.
  • Tests to detect infectious diseases, such as Toxoplasma and Bordetella serology and blood culture.
  • Blood pressure measurement.
  • Electrocardiogram looking for arrhythmias.

¿There is a test to determine the risk of hypertrophic cardiomyopathy?

If the feline is going to be reproductive or is a cat of certain breeds, it is advisable to carry out the genetic test for hypertrophic cardiomyopathy, since it is known that it derives from genetic mutations of some breeds such as the Maine coon, ragdoll or the Siberian. Currently, genetic testing is available to detect known mutations only from the Maine coon and the ragdoll. However, even if the test is positive, it does not indicate that you will develop the disease, but it does indicate that you are at greater risk. As a likely consequence of unidentified mutations, a cat that tests negative can also develop hypertrophic cardiomyopathy. Because of this, it is recommended that annual echocardiography in pedigree cats with family predisposition to suffer it and that they are going to reproduce. However, due to the high dropout rate, we always recommend opting for sterilization.

Treatment of heart murmur in cats

If the diseases are cardiac, such as hypertrophic cardiomyopathy, medications for the correct function of the heart and that control the symptoms of heart failure in cats, if it occurs, are key:

  • Drugs for hypertrophic cardiomyopathy They may be myocardial relaxants such as the calcium channel blocker diltiazem, beta blockers such as propranolol or atenolol or anticoagulants like clopridrogel. In cases of heart failure, the treatment to be followed will be: diuretics, vasodilators, digitalis and drugs that act on the heart.
  • The hyperthyroidism can cause a problem very similar to hypertrophic cardiomyopathy, so the disease must be controlled with drugs such as methimazole or carbimazole or other even more effective therapies such as radiation therapy.
  • The hypertension can cause left ventricular hypertrophy and congestive heart failure, although more infrequently and usually does not require treatment if increased blood pressure is treated with drugs such as amlodipine.
  • If you present myocarditis or endomyocarditis, rare in cats, the treatment of choice is antibiotics.
  • In heart diseases caused by parasites such as heartworm or toxoplasmosis, a specific treatment must be carried out against these diseases.
  • In cases of congenital diseases, surgery is the indicated treatment.

Since the treatment of the murmur in the cat's heart depends, to a great extent, on the cause, it is very important to visit the veterinarian to carry out a study and define the drugs to be taken.

This article is merely informative, at AnimalWised.com we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

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