That's terrible! What a horrible week you are having. I'd get a baby monitor out there and have my rifle ready for the next time. I hope you nail those ba****ds!
I hope your poor dog is OK. I didn't read your post about it going blind.
One thing you can do when you get your new girls back in the hen house, buy an electric fencer, barbed wire and place strands 6", 12", 24" and again at 3'. Next, place peanut butter on the fence. All animals, including deer have to smell it and when they do, its a jolt that will not kill them, yet for a dog/coyote, they will not associate good smells with good food.
Placing poison in meat is against the law, granted, if it was me, I would be that desperate, yet what if your own dog got out, smelled the meat, ate it.
No matter how you look at the whole thing, its devistating.
There are mesh fencing that you can that you can electrify, the more strands and insulators, the better off you'll be.
We had a problem with Moose taking down a fence once and getting in with the cattle, so we boosted that fence up to HOT and if a blade of grass touched it, it would burn. We had to trim under the fence that summer, but never anymore problems with moose, either it learned to step over it or he didn't care for the feeling! lol. (it was not enough to kill or damage any animal, but it was not pleasant to touch).
Good luck and so sorry to hear of such things. Nothing about nature is kind, and even beauty has its down side.
Many blessings and take care.