Rouge H, I've had Cavaliers now for over 36 years. Further testing is probably not necessary but it would be good if a boarded cardiologist could osculate the heart. Regular vets often don't hear low-grade murmurs. Even a doppler is not invasive but most likely not necessary at this point.
There are excellent meds for mitral valve disease which can be of huge benefit. My now 14 year old Shimmer (Chadwick Candlelight) went into congestive heart failure in late Oct and we almost lost her. She's now on a diuretic (Spironolactone) twice daily (1 pill cut in half), Enalapril twice daily, and the "miracle drug" for Cavaliers, Pimobenden, twice daily. She's doing amazingly well for 14!
There are excellent meds for mitral valve disease which can be of huge benefit. My now 14 year old Shimmer (Chadwick Candlelight) went into congestive heart failure in late Oct and we almost lost her. She's now on a diuretic (Spironolactone) twice daily (1 pill cut in half), Enalapril twice daily, and the "miracle drug" for Cavaliers, Pimobenden, twice daily. She's doing amazingly well for 14!