The thought of shooting a dog is not a pleasant one. I almost shot one down at Chamber's Creek a few weeks ago. You are supposed to have your dog leashed at all times while there, unless your dog is in the fenced doggie park area. Plenty of signs posted to the fact. It doesn't stop a lot of people from disregarding the rules.
So we're down at the park, wife, daughter, our Lab, and myself. I have my dog on a leash....because I follow rules. I notice a couple walking with a Boxer/Rot mix, no leash of course. My daughter is about 50 feet in front of me, my dog, and wife, sitting on a blanket in the grass. All of the sudden the Box/Rot bolts right for my daughter from about 200 feet away. The couple starts shouting "it's ok he's friendly!" I don't care that they think their dog is friendly when it's running at my 12 year old daughter. I let go of my dogs leash and tell him to "go get Sara!" my daughter. My dog runs off toward her. I draw my 9 and aim at the Box/Rot. At this point the couple starts screaming "no, he won't hurt her!" I ignore this of course and keep my sights on the Box/Rot.
After my dog makes it to my daughter he turns and runs toward the Box/Rot. The Box/Rot is about 100 feet from my daughter and I put my finger on the trigger and yell at my daughter not to move. This takes place in a big open grassy field, no objects between my shot and the Box/Rot, and nothing in the background but grass due to the angle I'd be shooting from. At about 75 feet my dog and the Box/Rot collide and start jumping all over each other like long lost friends...just playing and having a good time. After a few seconds I holster my 9. The Box/Rot owners apologize...a lot. I'm still pissed and the adrenaline is still going so I didn't end the conversation in the most diplomatic way. I told them "A few more steps and I would have killed your dog!" They apologize again. I tell them to "Put your f@cking dog on a leash!" We walk away, they walk away, the end.