Cat and human hearts are similar in structure and function. Both have four chambers that contract and relax to move blood through the heart and four valves between the chambers and major blood vessels that maintain unidirectional flow. The sequence of contraction and relaxation is stimulated by an electrical impulse originating in the right atrium. Any abnormality in this structure and function of the heart constitutes heart disease.

Cats can be born with an abnormal heart (congenital heart disease) or disease can develop later in life either because of another disease (secondary heart disease) or for undetermined causes (primary idiopathic heart disease).

Left untreated, heart disease can progress to life-threatening heart failure. Heart failure exists when the heart is unable to match the body’s circulatory demands; a complex sequence of events is triggered, often leading to buildup of fluid in the lungs, which in turn leads to breathing difficulties. Turbulent blood flow (heard as a murmur) can result in blood clots (thromboembolisms) which can travel from the heart and occlude small arteries.

A cat with heart disease may not show outward signs until the condition is well advanced. By the time signs appear, the problem requires prompt action; therefore, early and accurate diagnosis of a heart problem can be the key to effective treatment. Interestingly, veterinarians discover most heart problems when they are checking a cat for unrelated reasons, often during the annual examination. Your cat’s heart is screened for any audible irregularities in rate, rhythm and beat. One of the first ways the heart makes up for its inability to pump enough blood is increasing in rate. The heart rate of a healthy cat is about 120 beats per minute when she is relaxed; this rate may normally be higher when she is stressed.

Once an abnormality is detected, further tests are needed to determine the location and cause of the problem and establish the best treatment. Radiographs of the chest are needed to evaluate the size and shape of the heart as well as assess the lungs for congestion due to heart disease. Blood tests and blood pressure measurements are often essential to determine if your cat has secondary heart disease due to underlying thyroid or kidney disease. You may also be referred to a veterinary cardiologist for an echocardiogram (an ultrasound of the heart) or electrocardiography (evaluation of electrical activity of the heart). Only after appropriate testing can proper medication(s) be prescribed for your cat’s specific heart disease.

Treatment is lifelong, and periodic re-evaluations are needed to maintain good cardiac function. Fortunately, a cat can have heart disease and live a normal life for a number of years without symptoms of heart failure.