I'd be curious to know the laws in his area.

My neighbors can shoot my dog on sight if he were to enter their property. They have that right to protect their livestock, (horses and chickens, by the way). However, I have serious doubts as to my legal rights to shoot wandering livestock. The law views pets and livestock differently. I imagine I would get into a great deal of trouble for humanely dispatching the neighbors wandering steer and accidentally placing him in my freezer. Even if he was eating my prized petunias.