At 13, the poor thing is probably blind and not moving quickly. They certainly can’t really be a threat to anyone!
They are great “alarm” dogs. I just can’t imagine why they had to shoot it.
I would imagine the Pug was all worked up, especially being locked behind closed doors. When a dog with a pushed in nose gets excited and breathes hard they snort and get gurgely, sometimes people think it a growl.
This cop has no business with a gun, he is a danger to society.