I would never trust the invisible fences, especially with big dogs. My neighbour has a small dog and the fence works not too bad, but it's frequently not working. I've seen the dog walk through many times. Also with country properties, there's often dogs at large. With my Tosas, that could spell trouble if a dog wandered into my yard. If I were to fence my yard, I would look at at least 5' chain link with some sort of wiring on top to prevent jumping over. My boy can scale a 6' jump fairly easily, so a CC can surely do that.