Hello and bless your heart for rescuing little Powder Puff! She sounds so adorable! I don't have any experience with heart murmer, but wanted to wish you the best with her and I hope she can do well with this problem. I've done a search and have a few links you can check out, unless you already have seen them! One thing I learned when searching was that a level one heart murmur is the softest and it goes up to 6 being the worst. I am wondering why your vet didn't have much to say about it. Maybe you should get a second opinion? Best wishes to you and Powder Puff and welcome to YT! Here's some links:
http://www.faqs.org/qa/qa-2518.html http://www.thisisthenortheast.co.uk/...onemurmur.html http://www.vetinfo.com/dmurmur.html#...r%20in%20puppy http://www.backcsc.com/heart.html