Heart Murmurs in Cats

How are Murmurs Created?

Each heartbeat originates as an electrical impulse and eventually generates a muscular movement. The heart is a muscle that's "job" is to pump blood. Blood is pumped from the body to the heart, processed through the lungs, returned back to the heart and pumped out to the body. As the blood is pumped, it goes through four different parts of the heart or heart chambers. Between these chambers are "valves". A valve is a membrane that opens and closes to prevent backward flow of blood.

Heart murmurs can be caused from either heart muscle or valve abnormalities. If either of these structures do not function properly, the flow of blood is disturbed. This disturbance can cause "turbulence" in the blood flow that creates an abnormal sound that we refer to as a "murmur".

Heart murmurs may affect cats of any age or sex. They may also affect any breed, however some breeds are more prone to heart disease.

The prognosis (outlook) for animals with heart murmurs depends on the underlying cause of the murmur such as the type and extent of any existing heart disease.

What to Watch For

A murmur is an abnormal heart sound and is found only by listening to the heart. Occasionally a vibration or "thrill" can be felt over the heart. Signs of heart disease or secondary problems that may be associated with the mumur may include:

Some cats have no symptoms

Weakness

Collapse

Slow heart rate

Fast heart rate

Erratic heart rate

Difficulty breathing

Lack of appetite

Diagnosis

When a murmur is present, the goal is to determine the underlying cause for the murmur. Tests may include blood work, urinalysis, chest radiographs and an echocardiogram.

The "gold standard" for diagnosing the underlying cause of a heart murmur is a cardiac ultrasound (echocardiogram). It is performed to evaluate cardiac and valve function and identify underlying heart disease. Murmurs that occur in puppies and kittens can be very difficult to diagnose even for the most experienced veterinarians. Many pets may be referred to a board certified veterinary cardiologist for evaluation.

Thoracic (chest) radiographs (X-rays) may help determine if heart disease or heart failure is present.

Blood work, including a complete blood count and biochemical profile, may be performed to look for any underlying abnormalities. Some cats may be anemic, have an elevated white blood cell count, or have other organ dysfunction.

How aggressively one pursues the underlying cause of the murmur depends upon the likelihood of a serious underlying problem and if there are any other associated symptoms indicating the probability of heart disease.