That's an absolute.
Some people install fences of various heights ~ and I've heard that sometimes that can't be too high!
The animal here was supposedly restrained by an electronic fence. They don't always work. Besides, not everybody knows about them.
There is no reason to shoot a dog on it's owner's property except in extremely rare exigent circumstances (for certain breed profiles only).
Cops are supposed to be part of the community, not a cog in the statist system of citizen control.