WildBill wrote:.... all it takes it one word from the handler to "switch him on".
There are various methods of training a protection K-9, but I think the police have pretty well settled on the Schutzhund training. The method uses specific commands in German to 'switch' them on and off.
One of the local departments dogs where I used to live was named Greif (pronounced Gr-eye-ff). And while he was usually really focused when on the job, he was still a dog. A couple of stories existed about him dropping back to regular dog mode. One was where they were going through a house searching for drugs, and he stopped to snack on some Cheerios in the floor. Another was when he was turned loose on a suspect that was running out the back of the house. As he exited the house a rabbit ran out from under a bush, and he went from chase the bad guy to chase the bunny mode for a few seconds. His handler quickly got him back on track and he was able take down the bad guy as he tried to scale a fence in the back yard. Overall though, he was pretty solid on his training and had been a BIG benefit to the officer and the department as a whole on numerous occasions.
