Just going to chime in a little. First off, pointing blame is unhelpful. Accidents happen, dogs are dogs. Saying emphatically NO the dog cant be trained to behave otherwise is a disservice to the dog and their family. And don't let Cesar Milan here you say that
I believe it comes down to this :
1. how much work are you willing to do?(put up fences, training, purchasing things to help, cost of recouping losses, etc)
2. which is your first priority? (Family pets become family, which is "more" family dog or chicks? hard question to ask, and no one can answer it for you.)
3. can you live with, and still be happy with the choices you make?
I have faith, in all my years of sharing life with all kinds of animals, Ive only had 1 scare me to the point I couldn't/wouldn't work with them. A lovely Sheppard/Chow mix who grew up with my infant son, a huge white bunny and a parakeet, they would lay on the floor in a big pile of fur feathers and skin watching Rugrats
But one day sweet Sara dog was dreaming, jumped up and snapped the bunny up, throttled it and flung blood around the room, then plopped back down and snored. In that case, there was no thought, she was put down. People have told me I was wrong, people have told me I was right, in the end, I did what I felt was best for me and I can live with that.
Co-habitation does work, but not every time! And sadly there is no "Always" or "Never" black and white set of rules, just as you have your own mind to make choices, so do animals. Trust your self, and make the best decision you feel you can. You'll get support either way.