Training of the dog (or rather lack of training) is usually the problem...not the dog itself.
THIS!
Every time I see someone blame the DOG for killing their chickens I have to restrain myself from pointing out that any and all dog/chicken interaction is in the hands of the human. You let them free range. You didn't train your dog. You don't have a secure fence. You don't have a secure pen. It's on YOU, not the dog.