I certainly am aware how fast dogs run.  I have a Chow Chow, American Boxer, Blue Healer and a lab mix.  My Boxer wears a shock collar to keep her in her yard as well and will not over run the collar.  The collar first vibrates, then beeps and if not stopped?  Will shock her.  The receiver on her neck is very easy to see as was this poor dogs.   He stated he was putting his child in the truck...meaning...he was at the truck.  Put the kid in..then shut the door... only takes seconds.  I might have believed his story if he had not shot the dog on its own property and only shot ONE time.  Instead he kept shooting and then left the scene of the shooting.  It would be interesting to see if the collar went off.  Not sure if mine records.