I have a Great Pyr that I adopted 2 years ago as a three-year-old. He was raised by a woman indoors, kept snow white....in other words, he was her baby. Her husband went on the road to work, and she went with him, unable to take Ben. He was being shuffled between the in-laws, and kept tied, so I adopted him. He had never guarded livestock, just his owner whose husband traveled. So he came to our farm, and immediately became an outdoor dog. Add to the mix our 8 year old Australian Shepherd, who is a pet and stays indoors. When my husband had to be hospitalized to have a heart valve replacement, we had to secure Ben and Kodi in the barn so they could be cared for in our absence. So Kodi became an outside dog and never wanted back in the house. Ben does not want to come inside either. Last spring, I began noticing that Ben would run, looking up to the sky, and bark at large birds that flew over, effectively enforcing a "NO-FLY zone. Last summer, we decided to get chickens, and purchased juveniles, 12 week-20 weeks. Ben was free to roam the property and Kodi is in a very large fenced-in area. When the chickens arrived, Ben just walked among them calmly, and the chickens paid him no attention. Kodi on the other hand barked from the other side of the fence, but she became aware that they belonged there, and now pays no attention when they come into her lot. In fact, she goes into the pen with me to feed my small CXs. The chickens now free range and go up at night or in very inclement weather, and Kodi and Ben watch them. Two times that I know of, Ben has prevented hawks from coming down after the chickens, by running and barking at them. Kodi stands watch inside her lot,and alerts Ben when she sees or hears anything, and he comes and investigates since he runs free. On two occasions, however, when Kodi has seen possums at night and has come over the fence to kill them. Otherwise she never challenges her confinement. The two of them seem to complement each other.
I guess my point is that both of my dogs were raised indoors as pets, one for 3 years, and the other for 8 years. I really never expected them to guard the chickens,but they have assumed a guardian role, and have done it well. What they have done must be instinct, because they have had no training. I guess they know what belongs here and what doesn't.