Heart failure occurs when the blood returning to the heart from the rest of the body cannot be pumped out fast enough to meet the demands of body tissues. Heart muscle disease is one of the potential causes of heart failure. Dilated cardiomyopathy is a condition characterized by a variety of changes in the heart muscle that result in pump failure. As the name implies, the heart chambers are usually dilated or enlarged, and the heart muscle itself is usually thin and weak, contracting with much less vigor than normal. The term cardiomyopathy literally means "sick heart muscle."
The primary abnormality occurring with DCM is impaired function of the ventricles due to decreased strength of the heart muscle. The left ventricle pumps blood from the lungs to the rest of the body, and the right ventricle pumps blood from the rest of the body to the lungs. When the heart muscle fails, pressures can increase and ultimately lead to left- or right-sided heart congestive heart failure. Reduced output from the heart may result in signs such as weakness, exercise intolerance, fainting, and shock. Heart valve insufficiencies, abnormal heart rhythms or arrhythmias, and the results of the body's compensatory responses to reduced heart muscle performance can compound the problems seen with DCM. Ventricular arrhythmias can often lead to sudden death, especially in boxers and Doberman pinschers. The development of an atrial arrhythmia called atrial fibrillation can have important short-term and long-term consequences for dogs with DCM. This arrhythmia can be seen in all breeds of dogs.
Medications are used to treat the consequences of heart muscle failure, to attempt to improve the heart muscle's ability to contract, and to normalize or improve rhythm disturbances. Drugs used to accomplish these goals include diuretics, digoxin, and angiotensin converting enzyme inhibitors. Supplementation with substances such as taurine or l-carnitine may be helpful for some dogs with DCM.
