Hi and welcome to YT
. So sorry to hear of your concern and worry over your little one, how scary. I have heard, though, that many puppies do outgrow their murmurs, so you may find that he will too. I know of many dogs that have lived full lives even with a murmur too. Please keep us posted on what you continue to find out, and best of luck to you and your little one....I know it's scary to hear anything at all is wrong w/ these precious ones.