On the surface it looks bad for the cop..but sometimes looks can be deceiving. I would have to see & hear more of the circumstance before passing judgement. It looks like the cop was appealing to someone in the house to come get their dog so it wouldn't have to be shot. If that is so, then the dog's owner is responsible for it's death!
I have a friend who is on a police swat team..you can't imagine how many Pit Bulls they have had to put down when raiding drug houses. Now the perps aree going for bigger, meaner dogs than the Pits. Mostly the dogs are not just naturally meaner..the drug peddlars make them that way..sometimes having had the dogs vocal cords cut, so the dog will actually sneak up on the cops.
When my grandson first arrived in Iraq..one of their tasks as Spec Ops Marines was raiding terrorist's "safe houses", often under cover of darkness. These mini-fortresses were guarded by mean dogs..which carried a warning bark. My grandson's immediate NCOIC had an Ontario Katana strapped in a scabbard over his back..for quick draw. The Sgt called it his "Hush Puppy"..
I also truly like dogs, having for many years bred, trained, hunted and competed with both Airedale and Jack Russell terriers. However, I was raised on a farm and don't confuse the value of animal vs human life.
In this case, we just don't have enough info.. the cop could have been wrong..the dog's owner may have been wrong.