I had the reverse problem last fall. I had 3 turkeys I was raising in a 10'x10' pen, 7' tall walls, and the turkeys NEVER left the pen, even though they could fly to the top and perch on the walls, if they wanted to, but never did. A neighbor's dog (pit bull mix) from several streets away was actually observed by my next-door neighbor going to the door of the pen and pulling it open, and squeezing into the pen, grabbed one of my turkeys, pulled her outside, and them tore her apart, where she could be seen doing so by my neighbor and the patrons of the local bar that can see into my backyard (open yards, as we are in a small township where few build fences) saw the dog doing it. So, what does one of the bar employees do? They called the sheriff and reported that MY turkey was attacking the dog!!!! Sheriff deputy showed up on my doorstep to find out what happened, and I said I don't have a clue, because I didn't observe anything, and found that one of the turkeys was missing and the other 2 were traumatized. The next day, the dog showed up again, and was ready to do it again, but this time, she was restrained because the next-door neighbor and I were outside, talking about the events from the day before, and he was the one that pointed out that it was this same dog that did it the day before. We got pictures of the dog in the alley, barking at us because the dog wanted us gone so she could go in and attack the turkeys again. I turned the photo over to the deputy as proof. Shortly after that, the dog was gone... haven't seen her again. I'm afraid of putting any birds in that pen again, so am about to replace it entirely with a much more secure structure. Waiting for it to be delivered tomorrow.
Because I live in a township, I cannot use a gun to kill any stray dogs that come upon my property to kill my 'livestock'. But the laws of my state say that I can, and not be legally liable. Documenting what happened to the sheriff establishes precedence to protect me against future claims by anyone saying I killed their dogs.