One of the commonest causes of deaths in dogs is heart failure due to mitral valve regurgitation. Not sure how successful an open heart operation using cardiopulmonary bypass could be in dogs. However there is a solution for those rich owners who want their dog to live forever.
I have come across this video of a device that can be used to correct the incompetence.
Only in America - however I suppose if proof of concept is obtained in dogs and the device lasts a few years in situ why stop there - I suspect that Mitral Seal for Humans will soon emerge.