Does this happen with allot of Chihuahuas. When I first brought Charlie home he had allot of sable throughout his coat his ears where stable and his mask was very dark. Now he is losing all that dark colouring in his coat and lots turning into a fawn colour. Even his ears they used to be really dark and now all that's left is a bit of darkness on the tips of his ears. His face is still dark and I hope he at least keeps that. Has anybody else experianced this with their Chis??