Wow, lots added.
I didn't say I wouldn't do it, I think it's impossible to say if you would do something so horrible in the heat of the moment unless you are in said moment. Lots of people train as soldiers and think they can go into to battle and kill people, and end up freezing in the moment.
Using the exact scenario as it was laid out in the link, I would like to think I'd have the presence of mind to know that the kid did something wrong, to know the type of damage a large breed dog can do to a finger, how septic a dog's stomach is ... the fact is, when a child is in danger, you stop thinking. Ask any parent whose child has been in danger. I remember a time when my god daughter cried out and saw a stranger near her, I was moving before it even registered and had the guy against the wall despite the fact it was a bee that caused the cry out. This wasn't even a blood relation. Luckily I've never been in a point where it's been my own.
And it's not like I don't feel sorry for the kid, I do.
I do not, however, feel any pity or sorrow for the father. The blame lays on him for not teaching his kids properly. Even professional trainers will tell you you do not reach into your dogs sleeping kennel. If the best trained dogs will defend their space even against alpha owners at times. It is no different than trying to take food from a dog. If you can't teach family members how to treat a dog, you shouldn't own one. Anyone entering my house when I owned a husky and a husky/pitt mix were told the rules: both adults and children. Number one was not to reach for the dog when it was eating something. Number two was not bothering the dog when it was in it's sleeping kennel. Along with all the other typical rules (don't put your face near his/hers, don't sneak up on it, don't scare it, ect). Every time. Learn how to take proper care of your pets, be their dogs or fish or whatever.
So in this particular case, a dog lost it's life because it's owner was either too lazy or too ignorant to teach his children correctly. That is what makes me mad.
As skjl47 stated, animals can not speak for themselves when something bad happens. But I believe this is reason they should be more protected, just as babes and toddlers are, rather than less protected. Do I think the man should be brought up on charges? Absolutely. I see no difference between someone that shoots a person in error and a dog in error. If I were to shoot someone I 'thought' was about to enter to my house, and it was proved otherwise I would still expect to see a trial.