Lightning's face started lightening up at about 5. His entire head is white now (he's 12). Stomps died at about 14 years old, and his muzzle was hardly gray. Stomps' teeth were horrible from the time I got him, so at 6 he had the teeth of a 12 year old. Lightning at 12 has the teeth of 6 year old. So it is very difficult to age a dog.