It will stop them when they know you are there, but will do nothing when they think or know you are not present. This is what is so wonderful about the shock collar, you can sit in the house and watch through the window and correct the dog. They think you are not there. To them, it is like being corrected by God and they will learn that they cannot mess with the chickens even when you are not present. Dogs are smarter than people give them credit for.