Personally, I have no problem with the dog that killed the baby, being put down. If a dog kills, or attacks a human (subject to the cause of, and severity of the attack), I don't take issue with euthanizing the dog.
I have a nine year old, 65 pound, intact Shepherd Lab X female, Silvia, who is a lap dog. I've had her since she was 9 months old. The only time I have ever heard her growl at someone, was when I had only had her for less than a week, and the pair she growled at, were quite sketchy looking characters. Not very long ago, I met a friend's seven year old at school and walked her home. I had Silvia with me. Though not used to kids, she was cuddled by eight kids at once. Silvia was a little uncertain at first, but within ten seconds, she was in heaven. Even this gentle old dog, I would not leave alone with a baby.
The dog in the story you refer to, was at least nine years old, living in Nevada, and mauled a 6 month old Hawaiian baby. That means that the baby was new to the dog. A dog (or cat,especially) can get jealous, especially when this new, noisy creature, with the shrill voice and jerky movements, suddenly becomes the centre of attention. The dog may also have been investigating the baby, and was grabbed or pinched by the baby. Only God knows what happened.
Unfortunately, the mother left the baby unattended and not out of harm's way, for just a couple of minutes. She'll have that to consider for the rest of her life. Hopefully, God will give her the grace not to focus on this but to move on.
“The dog may also have been investigating the baby, and was grabbed or pinched by the baby. “
Then why would you want such a nice dog ‘put down’?