Many Veterans returning from active duty in war zones develop posttraumatic stress disorder (PTSD), which includes symptoms of hypervigilance and increased anxiety. A new technique being studied is to provide trained service dogs to Veterans suffering from PTSD. Among other things, the dogs can be trained to respond to the command "Block" by taking a protective position in front of the Veteran and to respond to the command "Sweep" by entering a room before the Veteran and barking if there is anyone there. First, discuss how the dogs might have been trained to respond to these specific commands. Second, when the dog is paired with the Veteran, what training might the Veteran require, to maintain the dog's behavior (i.e., make sure it does not extinguish)