Originally Posted by Barkingdog
I never heard that before, I always heard that small can live longer.
In general, yes, maller lives longer. But there are genetic tendencies in some lines, and many smaller dog will get mitral valve disease. The Cavalier folks are usually most knowlegable about this, as it is very common in their breed: http://www.cavalierhealth.org/mitral_valve_disease.htm
There are other heart problems too. At 2 years old, to have this advanced heart disease, is so sad. I hope that we get some encouraging news...