Mystic, my sister's cat, is solid black. He's 16 now and is greying, but not on his muzzle like a dog. He has grey hairs scattered throughout his fur now.

Lots of dogs grey even very young. I have a five year old black and tan husky mix who's muzzle is so grey he looks at least five years older! I know exactly when he was born. A good friend of mine saw him enter this world and has his littermates. He's definately only five! Lots of people comment on how active Franklin is "for an old dog" LOL