We have a 13 wk old pup and an adult ex racing greyhound. He is extremely patient and puts up with all sorts of pup shenanigans. Bit every morning they do this mad scary running around where he pins her down with his mouth at her throat. He jumps away if she squeals and stops if I tell him. Meanwhile she keeps coming at him for more! Him being the breed he is, it's the spec of it that freaks me out and the size difference. Don't want to stop them playing but...