Beyond 9 Lives: How to Spot a Heart Murmur

This is a sponsored post by veterinarian Elizabeth Arguelles, owner of Just Cats Clinic at Lake Anne Plaza. She writes weekly on Reston Now.

One of the specific things your veterinarian checks for during routine examinations is whether or not a heart murmur is present. Heart murmurs can happen in any cat at any age, but are particularly common in certain breeds. While it can be alarming to learn that your cat has a heart murmur, not all are dangerous. Cats with more severe murmurs can be managed with good care and with the help of a cardiologist.

What is a heart murmur?

A heart murmur occurs when there is turbulence in the blood as it flows through the heart. It can be heard as a whooshing sound that occurs during the normal heartbeat cycle.

The louder the murmur, the greater the turbulence in the blood passing through in the heart. However, the murmur’s loudness does not always correlate with the severity of the condition or its cause.

Heart murmurs are graded on a scale of I-VI in accordance with their intensity. Grade I murmurs are very soft and quiet, and those of Grade VI are so loud that they can often be felt through the cat’s the chest.

Murmurs are also characterized by their duration and where in the heart cycle they occur. The location also plays a role in determining the volume. Most of the feline murmurs occur during systole, which is the phase of the heart cycle when the heart is contracting to pump out blood.

What kinds of murmurs are there?

There are several different types of murmurs. Some are “innocent” or “physiological,” whereas others are classified as pathologic. An innocent or physiological heart murmur generally has no impact on the cat’s health. It typically has a low intensity, such as Grade I-II out of VI, and does not cause any symptoms or clinical signs. Pathologic murmurs are stronger and tend to affect your cat’s overall health.

Different murmurs are caused by a variety of underlying conditions. For example, a type of innocent feline murmur is often found in young, growing kittens initially appearing around six to eight 8 weeks of age, but typically disappearing by four or five months. Some adult cats can exhibit a physiological murmur when their heart rate increases due to stress and then disappears when the heart rate returns to normal.

Pathologic murmurs often occur because of structural problems in the heart like cardiac disease. These murmurs interrupt or disturb the flow of blood, thereby creating turbulence. Examples of such defects may include a leaky heart valve, a thickening or narrowing of a valve or large blood vessel, or an abnormal hole between the heart chambers. Pathologic murmurs can also be caused by issues that are “extra cardiac” or unrelated to heart disease such as anemia, hypoproteinemia and fevers. Some structural heart problems can be congenital like ventricular septal defects (VSD) or atrial septal defect (ASD). The most common type of acquired heart disease in cats is cardiomyopathy, or weakening of the heart muscle.

How dangerous is a heart murmur?

The prognosis depends entirely on the cause and severity of the murmur. In some cases, especially for innocent or physiological murmurs, no treatment other than monitoring is necessary.

Pathologic murmurs are a greater cause for concern, and the first step is detecting them. Structural or extra cardiac problems are usually accompanied by symptoms caused by the disease. The most common signs include poor appetite, weight loss, breathing problems, pale gums, lethargy or weakness. Because cats are stoic, though, these symptoms may be subtle until the disease advances. It is crucial to have your cat’s heart checked annually at physical exams to catch any potential underlying murmurs or heart disease.

If your vet does detect an abnormal heartbeat or a weak pulse, further diagnostic testing will likely be necessary to determine a treatment plan. Typically a referral to a veterinary cardiologist for further exam and testing like an echocardiogram is needed. The echocardiogram determines the size and movement of the heart while beating, and the Doppler measures the blood flow. Regular monitoring throughout your cat’s life is essential after a heart murmur or heart disease diagnosis. But with the right care and treatment, your furry feline can live a happy and healthy life.

For more information please visit our Feline Health Library.