ABSTRACT
A variety of etiologies cause myocardial disease and dysfunction. Primary (idiopathic) DCM is the most important cause of heart disease in many large breed dogs. Cardiac rhythm disturbances can be an early manifestation of myocardial disease. Idiopathic DCM is characterized by left ventricular (LV) or biventricular dilation and impaired systolic function unexplained by congenital or valvular heart disease, hypertension, or coronary disease. DCM as an entity probably represents the end-stage of different pathologic processes or metabolic defects involving myocardial cells or the intercellular matrix. DCM appears to develop insidiously over a prolonged period in most cases. Atrial fibrillation (AF) and other atrial or ventricular tachyarrhythmias are common. Idiopathic DCM is most common in large and giant breeds of dog, especially Doberman Pinschers, Great Danes, and Irish Wolfhounds. DCM is diagnosed most often in middle-aged dogs and the occurrence of overt DCM increases with age.
