Heart Murmurs in Cats

If your vet discovers a heart murmur, that alone is not an actual diagnosis. Rather, it can lead to the discovery of an underlying problem. Not all heart murmurs affect the health of your cat, but if heard, it may be best to still have your cat fully assessed.

When your veterinarian uses a stethoscope to listen to your cat's heart, an abnormal sound, known as a heart murmur, may be heard. Typically, the heart makes two distinct noises as the heart valves closes. Murmurs are heard between these normal beats. The more severe murmurs are capable of drowning out the average heartbeats.

Symptoms of a heart murmur can vary widely depending on several characteristics. Some cats may not exhibit any signs at all. However, there are a few clinical signs to lookout for:

• Pale gums
• Lethargy
• Weakness
• Abnormal or congested breathing
• Rapid or difficult breathing
• Loss of appetite (anorexia)
• Weight loss
• Coughing
• Collapse

Types

Heart murmurs are classified as congenital, acquired, and innocent/physiologic.

• Congenital: This type is present at birth, and is commonly caused by heart defects or diseases.
• Acquired: Cats with this type develop it later in life. It is the most common type of murmur.
• Innocent/Physiologic: This has no impact on a cat's health, and is commonly found in young kittens.

There are a number of conditions that can disrupt blood flow, thus causing heart murmurs. Common causes include:

• Hypertension (high blood pressure)
• Hypoproteinemia (low protein levels in the blood)
• Hyperthyroidism (excess thyroid hormone)
• Hypertrophic cardiomyopathy (heart walls thicken and restrict blood flow)
• Anemia
• Blood clots in the heart
• Increased heart rate in nervous cats
• Obesity
• Pregnancy
• Emaciation

Heart murmurs are mainly discovered during a physical examination as your veterinarian listens to your cat's heart. Once the abnormality is found, your vet will further assess your cat. Initially, you will be asked about your cat's health as well as whether they have presented any clinical signs.

The vet will also grade the intensity of the heart murmurs while listening with the stethoscope. This grade is placed on a scale of I to VI. Grade I is barely audible, and it is heard on only one side of the chest. By Grade VI, the loudness has intensified. It can be heard in more than one location, and the vibration of it can be easily felt through the cat's chest wall.

If your cat presented no symptoms and was instead nervous during the physical examination, your vet may simply wish to re-evaluate them at a later date when they are calmer as the murmur could have simply been innocent. Likewise in young kittens that have a low-intensity murmur, the vet will just propose a re-evaluation in a few weeks.

In the case that your cat presents symptoms or the murmur appears to be caused by an underlying problem, your vet may order several diagnostic tests. Blood tests such as a CBC (complete blood count) is used to detect anemia or infections, and blood pressure tests are used to check for hypertension. Chest X-rays will also be ordered to look at the lungs and the vessel size and shape of the heart. An EGG (electrocardiogram) will be used to examine any irregular heart rate or rhythm.

Further, your vet may perform an ultrasound to exam the heart, a procedure known as an echocardiogram. An echocardiogram may be accompanied by a Doppler examination which detects the speed and the direction of blood flow the heart valves and chambers. This particular assessment is highly useful in determining the exact location of the cause of the heart murmur.

Any type of treatment always depends on what exactly is the underlying cause of the heart murmurs.

Monitor

In the event that heart murmurs are innocent, then your vet may wish only to monitor your cat. Regular monitoring ensures that no complications arise, and your cat remains relatively healthy. This periodic re-examination may occur every few weeks to every few months.

Medication

Depending on the cause, specific medication may be given to treat whatever condition that has been discovered. Medicine is useful in cases such as hyperthyroidism and high blood pressure. Nutritional supplements are also useful in treating cases of anemia. In the case of hypertrophic cardiomyopathy, some medication such as blood thinning drugs and beta blockers to relax muscles may be useful in providing some relief. Even so, cardiomyopathy is mainly treated with supportive care.

Surgery

If the murmurs are caused by a congenital disease, then your vet may recommend surgery. Any specific surgery will depend on the exact nature of the disease.

Depending on the cause of the heart murmurs, the outlook ranges. Those diagnosed with innocent murmurs live healthy and normal lives, and require no recovery and minimal management beyond routine examinations. If your vet has prescribed any medication, then it is best to take it as directed even if your cat appears to be in good health.

Depending on the diagnosis, lifestyle changes may be of good help to manage your cat's condition. These changes include managing diets as well as exercise. Also, be sure to still follow-up with your vet as only they can check whether or not a murmur has been resolved or may have worsened.