Heart Disease
Dr. Todd B. Friedland, DVM

Heart disease is fairly common in older dogs, and although seen much less often in cats, represents a fairly serious disease that requires proper care. Recently, with the advent of newer technology such as ultrasound, more has been discovered about the cause and effects of heart disease. The good news is that this new knowledge has led to major advances in successful treatment.



X-ray showing an enlarged dog heart due to heart disease.

There are two major categories of heart disease. Congenital heart disease means heart abnormalities that your pet was born with. Acquired heart disease is heart disease that develops sometimes during life. This article will deal only with acquired heart disease.

In the dog, the most common heart disease is called “Valvular Insufficiency”. The heart has 4 valves, or one way flaps that allow blood to flow in only one direction through the heart. When a valve becomes abnormal, it does not close completely, thus allowing blood to flow backwards through it. There may be one or more valves involved in the same dog’s heart. When the valves do not operate properly, the heart cannot pump blood through the body the way it was designed to do so. To make up for this deficiency, your dog’s body changes, or accommodates, trying to make up for the loss in proper blood flow. Usually, the heart enlarges, making it a bit stronger at first, but eventually the heart weakens further. Lungs, liver, and other major organs then become affected by the improper circulation, and the signs of heart disease will start to show up.

Signs vary with the part or parts of the heart that are affected. Labored breathing, panting for no known reason, decreased tolerance to exercise, and coughing are common signs of heart disease. Decreased appetite, weight loss, and gradual enlargement of the abdomen are more advanced symptoms.

Diagnosis is made by your veterinarian based on the signs your dog is exhibiting, combined with how the heart and lungs sound through a stethoscope. X-rays, electrocardiograms, and blood tests are commonly used to aid in making a very specific diagnosis. Most heart disease is incurable, but many can be controlled by medication and, in some cases, special diets. If your dog is diagnosed with heart disease, the most important step is to follow your veterinarian’s instructions precisely. Treatment is often complicated, but can work wonders for your sick pet.

Heart disease in cats is a bit more complicated. There are several diseases of the heart muscle, called “Cardiomyopathy” that are often difficult to diagnose without very sophisticated testing. Perhaps the most common heart problem we see is part of another disease called “hyperthyroid” disease, or over production of hormone from the thyroid gland. Simple valve disease is rare in the cat. Symptoms in the cat are less predictable. Often only a slight weight loss is evident, with the more typical signs coming very late in the disease. Heart murmurs can sometimes be detected, indicating heart disease. I cannot stress the importance of an annual physical examination for your cat, as the hearing of a small heart murmur may be the thing that saves your cat by early diagnosis of heart disease.

After the diagnosis is made, it’s time for therapy. Your veterinarian may or may not change your dog’s food. That will depend upon the severity of the condition and the type of food you are presently using. Medication is the hallmark of treatment. Most dogs are put on a type of drug called a diuretic. The most common drug I use is called furosemide. This changes the fluid distribution in the body, causing the fluid in the lungs to leave the lungs. In addition, medication will be prescribed to make the heart work better. A common drug for this purpose is Enalapril. For more severe cases, a drug called Pimobendan may be added. There are many other heart drugs, all with specific actions on this disease. They, however, would be determined by a specialist after ultrasound examination of your dog’s heart has been performed.


Dr. Todd Friedland graduated from Cornell University in 1972. During his first six years as a veterinarian, he worked and studied under some of the most respected veterinarians in the Long Island, New York area. He fulfilled his childhood desire to live in a small New England town when he purchased the North Windham Animal Hospital in January of 1978. He has built the former 4-room country practice into a well-respected, high-quality, 3-doctor hospital, providing the best in veterinary medical advancements, client service, sophisticated medical and surgical skills, and community involvement. He is a member of the American Veterinary Medical Association, Connecticut Veterinary Medical Association, and Connecticut Academy of Veterinarians.

"I have grown to enjoy all aspects of pet care, but my special interests now lie in getting you off to the right start with your puppy and kitten through early and proper counseling and spending that extra time with pets as they get older. Geriatric medicine is one of my greatest pleasures."

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