Tug is fine. When they are young as long as they aren't snarling or biting you it's okay. Just make sure you pet your dogs head while playing and get close to the mouth and used to it so they don't get older and nip or bite. My Milly plays that' way and the very rare time her teeth just touch my hand she lets go and licks me. Just make sure they know it's a game and if they get aggressive don't continue just put it away and try later.