[Jeff Higgins]

Sounds like there is more to the story. I would bet your client made a habit of letting the dog run loose. It may have been crapping in the neighbors' yards, digging up their gardens, chasing their kids and acting aggressively, etc.

Some jurisdictions do not respond all that well to neighborhood dog complaints. Mine, for example, "prefers neighbors work it out among themselves". What if a neighbor absolutely refuses to control their dog, despite repeated requests? I was on the receiving end of that situation, along with several other neighbors. We had one guy who simply would not control his dog. The city did pick it up several times when they just happened to see it loose, but they would not address the ongoing, collective concerns of the neighbors that were affected. They kept giving the damn thing back.

I'm not saying that's what happened here, but most folks don't just up and shoot the neighbor dog just for the hell of it. Your client has more than likely been an ongoing problem for them, and others.