Hi Indyalan, Ive got a lab with a grade two heart murmur, and my vet said it was possible it could go in the first few weeks. With nell it didnt, but to be quite honest, it doesnt affect her at all.
We have never stopped her running or doing anything a normal healthy dog can do.--nells is three and still mad as a hatter.
I,m sure one of the more experienced on here will be able to tell you more.