The comparisons of some idiot shooting children for coming into his yard and shooting a dog are ridiculous and hold no water to any "dog shooting" situation.
On another note: I have a 75lb Black and Tan Coonhound in my backyard that wouldn't hurt a flea, but I wouldn't be shocked for a minute if he ever got out and went into someone's yard with a 3 or 4 year old that a parent would end him right there. Attacking or not. It would be hard as parent to see a dog that big approach your child and not take some kind of drastic measure. Would I shoot a Coonhound in that situation? Doubtful, but I wouldn't be shocked if someone else did. It would be sad for sure...even if the dog did attack and it was YOUR "beloved pet", if someone had to kill it, you're not going to be happy about it, but it is what it is.
Oh, and after being bitten twice in my LE career by Pitbulls, I don't care what any animal lover says, it would be hard for me not to shoot it if it came in my backyard with my kids there...I'm not worried about if it were just me cause that would just turn out however it turns out, but if my kids are out there...well, more than likely that dog has met it's end.