Heart disease is defined as any abnormality of the heart. It encompasses a wide range of abnormalities including congenital abnormalities (see Congenital and Inherited Anomalies of the Cardiovascular System), as well as anatomic and physiologic disorders of varying etiologies. Heart disease can be classified by various characteristics, including whether the disease was present at birth or not (eg, congenital or acquired), etiology (eg, infectious, degenerative), duration (eg, chronic or acute), clinical status (eg, left heart failure, right heart failure, or biventricular failure), or by anatomic malformation (eg, ventricular septal defect).

Heart failure is any cardiac abnormality that results in failure of the heart to deliver adequate blood flow to meet the requirements of metabolizing tissue. It is a clinical syndrome in which congestion or decreased peripheral perfusion arise as the final consequence of heart disease. Heart disease can be present without ever leading to heart failure. Heart failure, however, can only occur if heart disease is present because it is a consequence of heart disease.

Last full review/revision July 2011 by Daniel F. Hogan, DVM, DACVIM (Cardiology); Suzanne M. Cunningham, DVM, DACVIM (Cardiology); Daniel J. Hall, VMD; Mark D. Kittleson, DVM, PhD, DACVIM (Cardiology)