thanks janeyk, that is a really useful link. the vet didnt say what grade it is, i should have asked him but i was upset at the thought of my precious smudge having something wrong with his heart. our gorgeous little dog jack developed a heart murmer when he was about 12. that was only grade 3 but he died of heart failiure soon afterwards and i cant get that thought out of my head. i know i should and each case is different. but its hard to do.