I'm so sorry Buttercup.

I found out earlier this year that my Little Dog had a grade 3 murmur but the vet said it was nothing really to worry about. However, she did end up passing away a few months later. She did have a coughing problem and seizure problem that the vet attributed towards the murmur. We had thought she had a collapsing trachea all along (that's one of the reasons she went to the vet and found out about that, I was getting ready for her to have surgery on the trachea)!

I'm confused about that and am curious to see what else your vet says about them!