Well, first is my ancient GSD I rescued 4 years ago. She watches out for my chickens and Guineas when she is outside, but she spends her time where ever I am, and that is indoors or out depending on what I am doing. Her name is Millie, spayed, and she is at least 11 years old.
Second is Pal, he is a 3 year old Blue Heeler/Blue Tick Hound cross, neutered male. He is my guard dog, he runs off all predators including ones that fly! He helps push my horses in from bottom pastures when needed, and he stays out all day working with my ranch hands and watching over the ranch.
Third is Pal and his faithful sidekick Talley, a 3 year old Catahoula Cur. She is the crazy one, but she adores Pal and he has taught her to help him watch out for the horses, donkeys, and birds we have on the ranch. She is a good barker and alerts to pretty much everything, all the time! It's ok, it scares off any would be problems and keep coyotes at bay around here.
I also have a 3 legged GP that is 4 years old, but he stays in and only is outdoors for short periods of time. He is scared spotless of the horses and donkeys, and has eaten a couple of Guineas before I got him to stop that behavior. He will watch the flock if he's out at all with them though, but he just isn't out all that much. If he had all 4 legs he would be an outside dog and would have had a lot more confidence to guard.