Eh. Such a dog is workable. You just gotta step up on your end of training process. Most of my dogs killed a bird or two during training process but those that did not were generally not effective guardians either.???WHAT!
Probly best not to give the first bit of info a try unless you absolutely have extra hens to spare or the dog is an easy scare. I'd bet a chicken killer with the mind set of going for it for whatever reason playing or simply to eat it would still be somewhat of a match for a 4 lb hen. You know one crunch of the jaws with more than over 2000(a ton) of PSI (pounds per square inch) with sharp daggers at the end of these levers is a pretty bad @$$ weapon.
I'd either keep the dog away from the chickens or get shed of it or the chickens if there is no way for them to cohabitate.