Mitral regurgitation (MR) associated with degenerative mitral valve disease (DMVD) is an acquired cardiac disease that appears most commonly in dogs. Exacerbation of DMVD is related to age, the degree of MR (murmur or countercurrent jet), and the degree of valvular degeneration. Deterioration of the clinical signs and prognosis of DMVD occurs because of mitral valve degeneration, mitral valve prolapse, and progressive thickening and rupture of the chordae tendineae. When compensatory functions of thepulmonary vasculature for MR fail, cough and dyspnea due to pulmonary congestion and pulmonary edema occur. Dyspnea due to severe pulmonary edema is treated with diuretics, oxygen inhalation, nitrate, cardiotonics, and vasodilators. Recently, the controlled QUEST study demonstrated that pimobendan is associated with improvements in quality of life and survival. However, survival following DMVD and/or rupture of the chordae tendineae is no longer than 2 year. Because medical treatment of MR with cardiovascular drugs is palliative, MR generally progresses to severe disease. Therefore, a radical cure to reduce MR requires surgical intervention.
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