It was very unfortunate to learn the fate of the two dogs killed in Tagish some time ago. It certainly did not have to end that way.
The fault here is definitely shared by the irresponsible dog owner and the gun-slinging neighbour.
The owner of the dogs should try to grab a sense of where she lives. It was simply wrong to let your dogs run loose and terrorize the neighbour’s poultry and, apparently, it was not the first time. No doubt it is also the reason why one of your dogs was pregnant.
The neighbourly thing to do would have been to approach the person and ask to make restitution.
To the dude with the gun, you never had to shoot those dogs.
You also could have approached your neighbour and informed her of the problem and asked for restitution.
You also could have taken them to court. That way you could have built yourself a proper chicken coop.
Just because there is a piece of legislation still on the books from the Dark Ages does not mean you should act upon it. I mean, internment camps were once legal, too.
There was simply no reason for you to do what you did. You had choices and chose the lowest common denominator, the end of a gun.
The entire mess could have been averted by the application of common sense.
Unfortunately, these days such a notion is not very common.