The story says that the dog was shot in the rear. Sounds like a trigger happy bicyclist to me...
The story says (the owner) said the dog was shot in the rear.
The dog escaped from its house while the owner was away hunting. This is a tragic story, but there may not be a real bad guy here.
Bad situation, it seems to me.
The story also says that the dog got out and it allegedly suffered PTSD as well as being a combat dog; a dog specifically trained to attack a perceived threat if necessary.
In other words it is a dog which required additional safeguards to keep it securely on the owner’s property.
The bicyclist, unable to deter the dog or summon its master, opens fire on an animal that is presumably moving back and forth. Not being an expert marksman, he misses his target and hits the dog in the rear.
Responsible dog ownership means making sure your dog will not leave your property. A trained service dog should also be with the owner at all times.