Two thoughts. Invisible fencing first. Yes, to a certain extent, it will work. But it is NOT foolproof, there is training involved, and remember, the batteries need to be replenished regularly. And, if something scares your dog, he will bolt, and then be unable to get BACK onto your property. They really are not a secure way to go. Have tried them, and know considerable people who have them. Also, they are not cheap. Second thought. You cannot "sheep proof" a dog introducing him to a ram. Believe me. When your friendly dog gets together with other dogs, they WILL run sheep. I'm out of sheep ranching because of local dogs. So, if you are in any kind of livestock territory, get the fence, and check it for holes regularly. Deer/rabbit wire is the best, so they don't go through the mesh.