I love animals, but if a neighbors pit bull came in my yard and acted aggressively towards my wife, my neighbor would have a dead dog.
I've already been on the phone with the sheriff's department. They wouldn't even talk to me about it. They said "you have to talk to animal control". I told the lady I already talked to animal control, but there wasn't a guarantee they would show up any time soon, and that I wanted to know what my legal options/legal implications were in this county if I killed those damn dogs next time they came on my property. I was treated to an abrupt silence, which was me being transferred to animal control.

I've been told by neighbors that the sheriffs department is damn worthless around here, but now I know first hand.
I've ---smurfing--- had it, and I am setting my loaded rifle right inside the garage door as soon as I get home tonight if animal control hasn't showed up by then.
And as a side note, my boss came in this morning saying that his neighbors pit bull came into his yard last night and mauled his large black lab. All he could find quick was a 22 rifle. He shot a warning shot into the ground next to the dogs and it didn't effect the pit at all, but scared the ---Cleveland steamer--- out of his own dog which got up and drug the pit hanging from its neck across the yard (like I said, BIG lab). Then he laid the 22 barell across the pits neck and pulled the trigger. That one finally did the trick to get the dog to let go. I told him he's damn lucky that pit didn't ditch the dog and attack him.