Of course it's always the owner's fault because you can't take a dog to court and make him legally responsible. The dog will always pay for the owner's neglect to keep him contained because that's just the way it is. Good dogs may escape despite an owner's efforts to contain him, but darn it, 99% of the time, the dog is allowed to roam or the owner hasn't fixed the place the dog is getting out which is the same thing, effectively, so to me, it matters not one iota to me why the dog is on my property. He's there and must be dealt with, especially in the absence of a decent animal control. Many rural areas do not have an animal control at all, so the property owner has to take care of the situation himself. I live in a rural area where dogs roam freely because the owners (and I use the term "owner" loosely--a dog isn't owned just because you say he is or because you may stick a collar sans tag on his neck)think that there is no leash law because it's the country. I am legally within my rights here to shoot a dog harassing or killing my chickens, and sadly, someone around here may find that out the hard way one day. I don't want to hurt/kill a dog, but I will if I have to defend my birds.
Two different neighbors of mine put up chain link fences for their respective dogs, spent all that $$$ so the dogs would not come over here and kill my chickens, putting them in danger of being shot, but neither neighbor keeps the dog in the fence all the time. I don't get that at all, I really don't. A dog does not "need" to roam to be happy. In fact, a loose dog is in danger from guns, cars, livestock, rabid wildlife, ticks, etc, etc. If you care about the dog, keep him on your property one way or another. It's really not brain surgery, for goodness sake. It really can be done. We have a picket fence for my dog that's within a 2 acre perimeter livestock fence with driveway gate that stays closed except when we're expecting a delivery. A dog has to either climb over or dig under to get to my birds, so he's not just "passing through" if he is in contact with my chickens. He made an effort to be there.
To the OP, I'm so sorry about Chloe.