Originally Posted by LesterOfPuppets

It is pretty meaningless without mention of a trajectory.

The bullet also could have entered the dog's hindquarters from the side. If you hold a bike between yourself and a dog protecting his territory, a persistent dog will pace back and forth barking in front of the bike and eventually try to get around the bike. I've had to fence of small packs of dogs and would have to continually shift the angle of the bike to keep them from ingressing. Dunno if this was the case but it is one other situation where "shot in the backside" doesn't necessarily mean that the shooter shot at a retreating dog.