I encourage electric fences. They aren't only effective, they are VERY SATISFYING (in a vengeful sort of way) when those dogs hit that wire - you will hear some serious yelping and they will high-tail it for home! (Also works with your OWN dogs, should you have any that aren't 100% trustworthy, and yet you don't necessarily want to shoot them....) You could solve the "immediate" problem by killing a dog who is doing what dogs do, or you could solve the problem permanently - for purposes of all future wayward dogs - by installing an electric fence to protect your flock. Also works for foxes, coyotes.... bears!? (I can't testify to that, but so I hear...)