I have a 12 pound chihuahua mix that needs to learn some manners. He's constantly nipping dogs legs when he wants to play, does it when they're playing and he's chasing him, while wrestling, when they get distracted from play. I know nipping is normal behavior, but he takes it too far when it's obvious the other dog isn't liking it. There've been a couple instances where he's persistantly chased a dog around nipping them for a long time while they're trying to get away. He's not trying to be mean or dominant, its just how he plays and for the most part it's annoying the other dogs. I've tried yelling no, calling him over and telling him no, distracting him, I just have no clue how to teach him limits here. Any suggestions?