Cardiomyopathy is defined as a primary disease of the myocardium. Most of the cardiomyopathies of animals are idiopathic diseases that are not the result of any systemic or other primary cardiac disease. The cause has been identified in some cases as a genetic mutation and in others as an inherited trait. In animals (primarily dogs and cats), cardiomyopathies are classified as dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and restrictive cardiomyopathy. In cats, if a specific cardiomyopathy cannot be identified, the disease is classified as cardiomyopathy, nonspecific phenotype. Cases in which a disease process has been identified as the cause of myocardial dysfunction are more correctly identified as secondary myocardial diseases or with a descriptive term preceding the term "cardiomyopathy" (eg, taurine-responsive dilated cardiomyopathy or hyperthyroid heart disease).
