I was wondering the same thing too. Izzy is nine months and he is still black on his body with a few silver strands here and there. His head is silver and tan.
Is the Yorkie the only breed that changes so much? My co-worker has one and we were saying how amazing it is that they change so much. Hers is all blonde. I have a picture of him when I brought him home and a recent one and its like night and day!