When I was growing up, an applicant who was too much of a panzy to handle getting bit by a dog was unlikely to be allowed to graduate the police academies.
Standards were higher back then, and some effeminate loser who did crap like this didn’t find defenders on the force. Members of the public didn’t have to raise cain about incidents like this because officers like this guy were fired for the good of the force.
They are taught when at the academy to shot the dog when confronted. It does two things. 1. eliminates a potential threat and 2. Shows everyone else just who is in charge at the scene.
I will bet that it was part of the officers initial training and part of the ongoing training at the local department.