 In 1981, Helmut Raiser published "Der Schutzhund" (English trans.by Armin Winkler, 1999 (), which radically changed Schutzhund protection training.In the US, the next great change in Schutzhund training is marked by the 1991 publication of "Schutzhund Theory & Training Methods" () by Susan Barwig and Stewart Hilliard.