My american eskimo dog nips/licks his upper legs make the fur kinda pink?

my american eskimo is pretty old he's 13 if i've been counting correctly, he is still energetic just sleeps more often. He has had flees once and that was last summer but haven't come back and he doesn't appear to itch his self. Now the problem is that I have caught him niping not really biting the fur on his legs then he licks his front legs repeatedly . I guess from doing this so much his legs are always looking like his fur went from white to a light pink. Its not lack of fur so you can see his skin but like a color change its wicked weir. This is annoying me because from a distance it looks like his legs are cut up. Also he doesn't do it when he's hanging around me like right now so im kinda thinking it might be when he's left alone which isnt that long? please someone help me find a solution