Any officer turned loose with a gun and a badge should have some knowledge of dogs - as they will encounter them often.
If they can't identify the cumbersome control collar on a dog that goes with an invisible fence - they shouldn't be let loose with a gun.
If a officer will panic and shoot to kill a dog still in is own yard - a dog with an easily visible control collar and a dog not known for viciousness - than that officer may well panic in a real danger situation - and shoot the wrong person...or a person walking down the street, whittling on a carving with a pen knife, bothering no one...even shoot him - at 30' - before he's had a chance to turn around to see if he's the one being yelled at.
Anyone turned loose on the public with a gun should have to pass a wimp test.