Did you put him on a raw food diet? I saw pics of a little doxie, that was almost totally grey on her muzzle and looked years older than she was. She was put on a raw food diet, and her color changed completely! Looked like a different dog! Better food better nutrients made a huge difference.
Let me see if I can find the pics. I was so amazed by them...
Before..
http://i894.photobucket.com/albums/a...9/c90d34cc.jpg
After..
http://i894.photobucket.com/albums/a...9/e9689b61.jpg