Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment

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Heart Murmur in Cats

Cardiac disease is thought to affect 15% of felines, which makes early detection crucial. Heart murmur in cats could be one indication that something is wrong, and that is why it's essential to keep frequent veterinary checkups.

Some cat heart murmurs are absolutely benign, and not all of them are signs of heart disease. On the other hand, a cat could already have an underlying heart disease without having murmurs.

Consult this guide to find out what heart murmurs in cats are, how to identify them, how to treat them, and how to keep your cat's heart healthy.

What are Heart Murmurs in Cats?

The heart is a muscle that moves blood throughout the body, giving it nutrition and oxygen. It has four distinct chambers divided into two upper (right atrium and left atrium) and two lower (right ventricle and left ventricle) heart chambers.  

There is a gap between each chamber that contains the heart valves that stop blood from flowing in the opposite direction. The typical pumping and the ‘lub-dub' heart sounds that a veterinarian hears by using a stethoscope, are brought on by the heart's valves closing. 

Heart murmurs are abnormal heart sounds that can be detected using a stethoscope to listen to the heart. This abnormal heart sound is caused by high velocity and turbulent blood flow.

A veterinarian cannot diagnose a cardiac murmur by simply listening to the heart. It is advised that tests be performed to identify the reason for your cat's heart murmur if a murmur is detected.

As mentioned earlier, cats may still have significant heart disease even when there are no symptoms. However, the presence of heart murmurs in cats is most often associated with an underlying problem.

Grading Cats Heart Murmurs

Veterinarians rate the loudness or strength of cardiac murmurs on a scale of one to six. This rating system is purely dependent on what the individual veterinarian hears while using a stethoscope to listen to the heart.

Grade I: These murmurs are only detectable to trained ears, or barely audible at all.

Grade II: Murmurs at this grade are not loud, yet audible.

Grade III: This is the most common grade. At grade three, heart murmurs are regarded as quite loud.

Grade IV: Categorized by veterinarians as a louder murmur that typically occurs on both sides of the chest and spreads over the heart.

Grade V and VI: Veterinarians refer to this level of murmur as palpable, which means that it can be felt by putting a palm on the cat's chest.

Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment 1

Types of Heart Murmurs

Heart murmurs can be congenital, acquired, and innocent/physiologic.


Congenital heart murmurs, which frequently accompany heart defects or diseases, are present at birth or shortly after birth. These murmurs can be very quiet early in life, and they are frequently not noticed until later when the cat grows and matures.


Although they can happen at any time, acquired heart murmurs typically appear later in life. It may have a benign cause or it may be linked to cardiac disease (cardiomyopathy). This kind of murmur is the most common.

Innocent Heart Murmur

Physiologic murmur or innocent murmur has no underlying cause. It can be found in cats of any age, but it is commonly present in young kittens. The presence of intermittent innocent murmurs has no impact on a cat’s health.

Symptoms of Heart Murmurs in Cats

Heart disease in cats usually doesn't show any symptoms to pet parents until the condition worsens and symptoms of congestive heart failure or aortic thromboembolism (blood clots) appear. As previously said, it is difficult to effectively identify a cat heart murmur on your own. The majority of the time, heart murmurs are discovered by chance during a routine physical examination using a stethoscope or during echocardiography.

The symptoms of a heart murmur might differ greatly based on a number of factors. Some cats might not show any symptoms at all. However, there are a few clinical signs to watch out for, such as the following:

  • Pale gums
  • Open mouth breathing
  • Chronic muscular atrophy or weight loss
  • Loss of appetite
  • Lethargy
  • Body weakness
  • Increased respiratory rate
  • Congested breathing
  • Coughing or wheezing
  • Exercise intolerance or panting with mild effort
  • Fluid from nostrils
  • Stunted growth in kittens with severe congenital causes
  • Hind limb paralysis
  • Hiding behavior
  • Painful vocalization
  • Gums turning blue, gray, or white
Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment 2

Causes of a Cat’s Heart Murmur

The turbulent blood flow within the heart is what causes a cardiac murmur. There are instances when a murmur is deemed “innocent” or “physiologic,” and other times when it is deemed “pathologic” or brought on by a disease. The presence of structural heart disease (cardiac illness), or an extracardiac issue (i.e., not caused by heart disease), might be the source of pathologic heart murmurs.

What Is an Innocent Heart Murmur?

A heart murmur that is innocent or physiological has no bearing on the health of the cat. Young, developing kittens, especially those whose growth is occurring quickly, frequently exhibit one sort of benign heart murmur. A kitten with an innocent cardiac murmur will typically outgrow it by the time it is about 4-5 months old. The murmur may first emerge at 6-8 weeks of age. This particular murmur is benign (not harmful).

Occasionally occurring cardiac murmurs in some healthy adult cats can be heard when stress causes their heart rate to rise. When the heart rate is normal, this kind of physiological murmur goes away and doesn't harm the cat's health. An innocent or physiologic cardiac murmur often has a modest intensity (typically Grade I–II) with no symptoms or clinical indicators.

What Abnormal Structure Causes a Heart Murmur?

In cats with structural heart disease, the blood flow is disrupted by some form of aberrant structure or defect, causing turbulence. An unnatural opening between the heart chambers, a thickening or narrowing of a valve, or a leaky heart valve are all examples of structural abnormalities.

Cats with structural cardiac issues might either be born with them or develop them over time. Ventricular Septal Defect (VSD) and Atrial Septal Defect (ASD) are the most typical congenital structural heart defects in cats. Cardiomyopathy is the most prevalent form of acquired cardiac disease in cats.

What Extracardiac Issues Can Cause a Heart Murmur?

Functional heart murmurs can result from a variety of extracardiac conditions, including anemia (low red blood cell counts), hypoproteinemia (low blood protein levels), fever or infection, pregnancy, obesity, or emaciation. A severe parasite infestation in early kittens, such as that caused by intestinal worms, blood parasites, fleas, or ticks, can result in anemia and/or hypoproteinemia. Adult cats with anemia may also be suffering from other underlying problems.

Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment 3

Diagnosing a Cat’s Heart Murmur

The majority of the time, heart murmurs are identified during a physical examination while your cat's heart is being examined by the veterinarian. Expect that your vet will check your cat’s blood pressure to rule out the presence of hypertension.

Your vet will further examine your cat after the problem is discovered. Your cat's health and whether or not they have displayed any clinical symptoms will be discussed in the beginning.

Depending on your cat’s clinical signs, your vet may do other diagnostic tests such as X-rays, an electrocardiogram (ECG), or a heart ultrasound test (echocardiogram). He will also advise doing some blood tests or other tests if he feels that the heart murmur is a complication of another condition.

There will be a full profile performed, which includes a blood count, thyroid, chemistry check, and urinalysis. This will assist your veterinarian in ruling out systemic conditions that may cause or contribute to a cardiac murmur, including anemia, thyroid illness, etc.

A unique blood test called Cardiopet proBNP may also be advised. This test examines an enzyme that is present when the cells of the heart muscle are significantly stretched. Although this test is effective for checking cats for serious illness, it still cannot identify the specific type of cardiac disease that is present. Running this test at routine checkups will be advised to look for any changes.

The gold standard for determining the underlying cause of a heart murmur is echocardiography or cardiac ultrasound. Occasionally, if an aberrant heart rhythm is detected, an electrocardiogram (EKG) is advised. Due to the high prevalence of systemic hypertension in middle-aged to older cats with underlying heart disease, a Doppler blood pressure test is also frequently carried out.

Treatment of Heart Murmurs in Cats

The underlying reason for a cardiac murmur or turbulent blood flow will determine the appropriate course of treatment for your cat. However, routine monitoring is required to make sure that no other issues arise. Physiologic heart murmurs do not require any therapy. The diagnosis will guide the treatment strategy, which may combine specific diets, drugs, and supportive care if the heart murmur is brought on by an underlying condition.

If your cat's cardiac murmurs are innocent, your veterinarian may merely want to keep an eye on them. Regular observation guarantees that no problems develop and that your cat maintains a generally healthy condition. This routine re-examination can take place every few weeks or months.

Any problem that has been identified may be treated with a specific drug depending on the reason. Cases like hyperthyroidism and high blood pressure can benefit from certain drugs. In the treatment of anemia, nutritional supplements are also helpful.

Some medications, including beta blockers to relax the muscles and blood thinners, may be helpful in treating hypertrophic cardiomyopathy and bringing about some alleviation. However, supportive care is the major method of treatment for cardiomyopathy.

Your veterinarian can suggest surgery if a congenital condition is the reason for the murmurs. The precise nature of the condition will determine the type of surgery needed.

Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment 4

Cat Breeds with Higher Rates of Heart Disease

Heart illness can affect any breed of cat, however, it is more common in some cat breeds, such as the following:

Recovery of Cats with Heart Murmurs

The prognosis varies depending on the origin of the heart murmurs. To determine whether the problem is progressing, it is important to closely monitor heart murmurs and heart disease.

Cats with CHF and various congenital cardiac conditions are frequently treated with heart medicines, heart supplements, and lifetime dietary adjustments. Those who are diagnosed with harmless murmurs lead healthy, normal lives and don't need any additional treatment beyond routine checkups.

Depending on what caused the murmur, the prognosis can be anything from great to dire. The prognosis is often favorable to excellent if the murmur is physiologic and no treatment is necessary. If an extracardiac condition or a treatable functional issue is the cause of the murmur, it may go away over time.

Depending on the precise type of heart disease that is present, the long-term prognosis for a cat with a murmur brought on by that condition varies. Your veterinarian will go over the potential treatments and your cat's prognosis because every situation is unique.

How to Prevent Heart Murmur in Cats?

Generally, cat heart murmurs can’t be prevented. However, if abnormal noise is detected in your cat’s heart during a routine examination, it is crucial that you follow your vet’s advice for follow-up checkups.

As mentioned earlier, the presence of a murmur doesn’t always suggest that a cat has an underlying heart condition that needs to be addressed immediately. On the other hand, there are also cats with significant heart disease without heart murmurs.

The most crucial lesson to learn is to take your cat to the doctor for routine checkups to rule out illness and, if necessary, start a treatment plan.


During your cat's examination, your veterinarian will hear any heart murmurs. The required workup for your cat will be explained to you by your veterinarian if they detect a new cardiac murmur. Although cats with heart murmurs can live long, healthy lives, the origin of the murmur must be identified.

Depending on the diagnosis, modifying your cat's lifestyle may be a helpful way to treat its disease. These adjustments involve controlling both nutrition and activity. There may be a need for medication in cats with hypertrophic cardiomyopathy.

Most cats will require routine follow-up care, which may include examinations, blood tests, and even echocardiograms. Additionally, be sure to keep in touch with your veterinarian because only they can determine whether a murmur has disappeared or even gotten worse.

Heart Murmur in Cats: Symptoms, Causes, Prevention, & Treatment 5

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