Its not just police shepherds mate.Theres lots of security dogs and sport dogs that will do the same.All they know in training is the decoy/helper runs off down the field cracking his whip holding his arm in the air then when the dog gets a mouthful of sleeve it gets a little fight which in reality is acting like a reward for getting the bite anyway.Youd be surprised how many dogs will back down if they are given a fight before they actually get the bite,some dont even need to be fought Just certain body languge ,an environmental situation or equipment that they've never witnessed before is en