SR, at one time, I did find a link to it, but I'm having trouble coming up with it now.
Basically what I have read and have been told by several LEO's is that you can use deadly force against an animal that is attacking you, another person, or a pet or livestock.
Now having said that there's always the possibility of the owner of said animal getting upset and trying to make your life miserable for shooting "fluffy".
We had new neighbors move in last summer 2 doors down from us. My wife and 2 kids and I were going shopping one Saturday morning. I was locking the front door while my wife was putting the kids in the van. I heard my wife scream and ran around the side of the house to the driveway. I see a dog of about 60 or 70 pounds standing there with about 4ft of broken cable hanging off it's collar. It's got hackles up and fangs bared. My wife's got the two kids between her and the open van door. I ran toward the dog angling to get my wife and kids out of the line of fire (if necessary). I got past the family and started to draw when the dog decided to be somewhere else. I watched where the dog went and put 2 and 2 together.
We put the trip on hold for a moment. I called animal control and got the regular sheriff's dept folks (animal control folks aren't on on weekends in this county). I reported what happened and what would have happened had the dog not backed down. I then put my weapon in the house and went down to talk to the owner of the dog.
She said, "Oh he's not used to people, it's best to just avoid him if he's in your yard". I replied, "Ma'am, that's simply not acceptable. I have two small children, I also refuse to "avoid" a dog that's not supposed to be in my yard in the first place and to have to run away from it. I fully intend to defend myself and my family if necessary. I have reported as much to the local sheriff's dept. Have a nice day".
That dog has not reappeared in our yard. They now keep him well restrained.