On the other hand, an out of control biting dog really does need to be put down quickly. I'd go back up the line 5 or 6 generations (if it was registered) and dispose of all the dogs in that breeding pool.
Dogs were made safe to be around through principles worked out back in the days of hunting and gathering. They are ~ foster the good, eat the bad now.
Oh come on. Almost all police carry tasers and batons in addition to their gun. If he does not have the taser he could have used the baton and hit the dog on the arms and legs and the dog would have let go. The man got scared because he is a coward and shot the dog, it is that simple.