Sheep ranchers in Colorado are using Llamas for the same thing.
But, a Llama isn't any protection against Mountain Lions.....
We've used a guard llama before to protect our flock from wild dogs and coyotes to great effect. They will chase predators and kick them to death. I don't know how they'd fare against a mountain lion but predatory animals usually won't risk a broken bone for a meal.
More recently, we've swapped out the llama for an Anatolian. It would mean less hassle for us to take care of, but some of our new neighbors call the city animal cruelty hotline on the regular to say that somehow it's a crime to keep a working dog outside any more. The inspector always leaves shaking his head but we still have to suffer his visit.
