all that playing and f*****g about they do is part of drive in dogs its how the hunt starts in wild canines, they focus on each other and through that eventually something else becomes the focus for them , the reason they dont do it at home is because there is nothing to kill in the back garden,,i've always focused my mutts on chasing ball in the off season if not working , it gives them a focus for their drive which includes me, a dog is always happiest in drive, and when he's playing about with another dog , he's having a great fecking time, thats why the recall goes out the windows because