Mitral murmur is a sign of chronic valvular heart disease, and is the most common heart disease of dogs. Mitral murmurs occur when the valve between the right atrium and right ventricle leaks, allowing “back-flow” of oxygenated blood back up into the lungs instead of out to the peripheral body. This bi-directional flow can eventually lead to congestive heart failure, but sometimes has no significant effect on the pets life span. No medications are needed unless the pet shows signs of congestive heart failure. These signs include night coughs, exercise intolerance, and bluish gums (cyanosis)