Hiker1, it appears you assume there will only be one dog, and that it will be left on its own, outdoors.
I have three, and they are primarily indoor dogs. When outdoors, the two large dogs play together. I suppose they'd be vulnerable to poisons, but a baseball bat, not so much.
I assume nothing - if you have 3 dogs, you probably aren't going to have a home invasion. If you have 3 dogs and 5 BG's decide that it's still worth the risk, you and your dogs have a serious problem.