Congestive heart failure (CHF) is a condition where the heart becomes weak and inefficient, usually due to an underlying disease such as heartworm, abnormalities of the heart muscle, or a genetic defect of the heart. It does not mean the heart stops beating, which is called cardiac arrest. The heart continues to work, but it doesn’t pump blood very well.

In hypertrophic heart failure, the heart muscle becomes enlarged and begins to require more and more oxygen. When they can’t get enough oxygen to meet their needs, heart cells begin to die, and the heart muscle weakens. In dilated heart failure, the heart pumps blood out very weakly and the chambers of the heart become filled with blood and enlarged, or dilated.

If the heart is unable to pump blood out effectively, pressure can build up in the lungs, resulting in a fluid buildup or congestion in the lungs that can cause difficulty breathing. Fluid can also build up under the skin, in the abdominal cavity, or in the chest cavity. Signs of this buildup of fluid include labored breathing, coughing, a low energy level, a lack of appetite, and fainting attacks.

Sometimes CHF can be cured by curing the disease that causes it. Animals who are treated for heartworm disease, for example, may recover well from CHF. CHF may not be curable in other animals, but veterinarians can use a combination of medications to make them more comfortable.

Veterinarians may prescribe diuretics, for example, which can remove from the body some of the excess fluid that causes swelling. There are also other cardiac drugs available, such as digoxin, which strengthens the heart muscle, and vasodilators, which dilate the blood vessels and make it easier for the heart to pump blood.

Copyright © 2009, American Animal Hospital Association

Reprinted with permission from the American Animal Hospital Association.