I think it's a combination of things, really. Though I do have very good pens and predator proof coops and the property is perimeter fenced, dogs can still get in. One climbed the livestock fence once. So, even if you have what you think is Fort Knox, you still may be faced with a dog on a...
I agree. In fact, it's my opinion that anyone who doesn't fence their dogs should expect that one day they will not return home-it's just a given. They have nothing to complain about, period.
First thing you do is put hardware wire or 2x4 welded wire instead of chicken wire up. Chicken wire won't keep anything out. And make sure it's fastened securely, with dig barriers at the bottom.
If you know who the dogs belong to, tell them they need to keep them at home or lose them. Then...