Learn which questions to ask your veterinarian if your pet is diagnosed with this condition.

Just like us, our dogs and cats can develop heart disease. What may surprise you is that they don’t experience heart attacks (myocardial infarctions) — the most common human heart health issue. This is likely because dogs and cats don’t live for multiple decades — the time needed for substantial amounts of plaque to accumulate within the coronary arteries. They don’t smoke cigarettes either.

Causes of heart disease in our pets

Dogs and cats can develop a variety of heart diseases. Some occur more commonly in particular sizes and breeds. Others, such as heartworm disease, affect dogs and cats of all shapes, sizes and breeds.

The most common cardiac problems in small animal veterinary medicine include:

Heartworm disease

In the infected dog or cat, long spaghetti-like worms set up housekeeping within the heart and arteries that supply the lungs. Left untreated, heartworms can cause both heart and lung disease.

Valve disease

Valves control normal blood flow in and out of the four chambers of the heart. Age-related heart valve degeneration occurs commonly, particularly in small-breed dogs. The resulting “valvular insufficiency” leads to heart failure in some, but not all cases. A relatively uncommon disease that can disrupt valve function is endocarditis, a bacterial infection that develops on one or more of the heart valves.

Congenital (birth) defects

This category includes faulty heart valves, wall defects between chambers of the heart, and blood vessels that are abnormally configured. These abnormalities alter normal blood flow in and around the heart.

Arrhythmias (alteration of the normal rhythm of heartbeats)

An abnormal heartbeat here and there causes no problem, but multiple abnormal beats can produce significant symptoms.

Cardiomyopathy (disease of the heart muscle)

The heart muscle can become too thin and flabby (dilated cardiomyopathy) or too thick and stiff (hypertrophic cardiomyopathy). Both conditions impair the normal pumping action of the heart.

Warning signs of heart disease

The heart is a muscular pump responsible for circulating oxygen-rich blood throughout the body. When the pump fails, not only can abnormal fluid accumulations occur within the body, but the animal develops symptoms caused by decreased oxygen supply.

Treatment of heart disease

While many canine and feline heart diseases are not curable, they are often very treatable. Medications are the mainstay of treatment for most types of heart disease. They are used to mobilize excess fluid accumulating in the chest, lungs and/or abdomen. Drugs are also used to decrease the heart’s workload, enhance the strength of heart contractions and prevent blood clots. If a heart rhythm abnormality is detected, an antiarrhythmic drug may be prescribed.

Some types of heart disease are best treated with surgery or a specialized procedure. They may involve installation of a pacemaker, repair of a defective heart valve or correction of a birth defect.


Prevention can reap wonderful benefits when it comes to heart disease. An example is the use of medication to prevent heartworm disease in dogs and cats. A thorough physical examination performed by a veterinarian once a year (twice yearly for senior dogs and cats) is another excellent preventive measure. These exams provide a golden opportunity for early disease detection. In many cases, the earlier heart disease is detected, the better the long-term outcome.

Whenever a serious disease is suspected or diagnosed, a second opinion is a good idea. Additionally, an echocardiogram and other advanced cardiac procedures require specialized equipment and skills. They are best performed by a veterinarian with extra training in cardiology, internal medicine or radiology.

Nancy Kay, D.V.M.,
is a small animal internal medicine specialist. She graduated from Cornell University College of Veterinary Medicine and completed residency training at the University of California, Davis. She is the author of the best-sellers Speaking for Spot and Your Dog’s Best Health, and her weekly blog covers a wide range of topics. Dr. Kay has appeared on the NPR show Fresh Air, and she has received several awards recognizing her achievements as a veterinarian and an author.