Primary cardiomyopathy in cats has been recognized in the literature as a clinical entity only since 1970. Prior to this, the recognition of this disease had been in association with aortic thromboembolism, an important complication of cardiomyopathy, because the etiologies of the several forms of cardiomyopathy are unknown classification has been based on nature of the hemodynamic fault or the anatomical abnormality that is present. The two most basic and common forms are hypertrophic cardiomyopathy and congestive cardiomyopathy.