ACVIM Consensus Statement Guidel ines for the Diagnosis and Treatment of Canine Chronic Valvular Heart Disease

This is the report of the American College of Veterinary Internal Medicine (ACVIM) Specialty of Cardiology consensus panel convened to formulate guidelines for the diagnosis and treatment of chronic valvular heart disease (CVHD, also known as endocardiosis and myxomatous valve degeneration) in dogs. It is estimated that approximately 10% of dogs presented to primary care veterinary practices have heart disease, and CVHD is the most common heart disease of dogs in many parts of the world, accounting for approximately 75% of canine cases of heart disease cases seen by veterinary practices in North America. CVHD most commonly affects the left atrioventricular or mitral valve, although in approximately 30% of cases the right atrioventricular (tricuspid) valve also is involved. The disease is approximately 1.5 times more common in males than in females. Its prevalence is also higher in smaller (o20 kg) dogs, although large breeds occasionally are affected. In small breed dogs, the disease generally is slowly but somewhat unpredictably progressive, with most dogs experiencing the onset of a recognizable murmur of mitral valve regurgitation years before the clinical onset of heart failure. When large breed dogs are affected by CVHD, the progression of the disease appears to be more rapid than that observed in small breed dogs. Cavalier King Charles Spaniels are predisposed to developing CVHD at a relatively young age, but the time course of their disease progression to heart failure does not appear to be markedly different from that of other small breed dogs except for the early age of onset. The cause of CVHD is unknown, but the disease appears to have an inherited component in some breeds studied. CVHD is characterized by changes in the cellular constituents as well as the intercellular matrix of the valve apparatus (including the valve leaflets and chordae tendineae). These changes involve both the collagen content and the alignment of collagen fibrils within the valve. Endothelial cell changes and subendothelial thickening also occur, although affected dogs do not appear to be at increased risk for arterial thromboembolism or infective endocarditis. Mitral valve prolapse is a common complication of myxomatous valve degeneration and represents a prominent feature of CVHD in some breeds. Progressive deformation of the valve structure eventually prevents effective coaptation and causes regurgitation (valve leakage). Progressive valvular regurgitation increases cardiac work, leading to ventricular remodeling (eccentric hypertrophy and intercellular matrix changes) and ventricular dysfunction. Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. The ACVIM Board of Regents oversees selection of relevant topics, identification of panel members with the expertise to draft the statements, and other aspects of assuring the integrity of the process. The statements are derived from evidence-based medicine whenever possible and the panel offers interpretive comments when such evidence is inadequate or contradictory. A draft is prepared by the panel, followed by solicitation of input by the ACVIM membership, which may be incorporated into the statement. It is then submitted to the Journal of Veterinary Internal Medicine, where it is edited prior to publication. The authors are solely responsible for the content of the statements.