Hello, i have a year and half old beautiful Pitbull. He comes from a champion bloodline, and great genetics. He is massive, very active, extreme appetite etc. Anyhow, he does have a heart murmer grade 2. I have talked to some people and they have advised that grade 1-6 are not extremely bad. But I need another professionals opinion. Since he does have this, if no symptoms continue (shortness of breath, hacking, basically no blood building into the lungs), will his lifespan be decreased and what would be the normal range of good health and etc.??