Not cruel at all. Intelligent working dogs love to work.They do not enjoy boredom and are more than happy to please their masters.
My father's dog recognised, somehow the sound of a Police Wolesley approaching our house in the middle of the night or early hours and would start barking in excitement thus awakening my father.It was a well practised routine. My Dad kept an old brown boiler suit by his bed at night and would get up don the suit over his pyjamas.Pick up his police cap,wellie boots and lead by the front door and take the dog out to the awaiting area car to be taken anywhere in London or home counties for a police job.
I often used to help my father as a villain with a starting pistol run from the dogs and brought down by them. Heavily padded right arm of course.The dogs loved doing it and if poorly trained did not always leave immediately on command but got a good old nibble in first.
I was no stranger to a Tetanus jab as a kid.