After growing up in an area where it was not uncommon for horses to get loose,I have seen this many times. I imagine they could have resolved the situation quicker by contacting the owner before shooting the animal instead of after.
By the way, a Percheron can really crumple a Dodge Dakota when it is standing in the middle of a road. I saw that happen too. I just think they were a bit quick on pulling the trigger from the story.
How do we know though? Many hours could have passed. No telling.