As a child my own german shepherd killed and/or skinned a couple of my show lambs. We were (*and still are) country folk. We had our dog put down so it wouldn't happen again to us or someone else. Its hard to accept, but much of society has lost touch with the agrarian world and what it takes to raise livestock. We have a right to protect our property and livestock. The dog was definitely and obviously where it didn't belong and you were well within your rights to protect your stock. Whether pets or not its your livestock and you can protect it. Its unfortunate that their dog was the perpetrator, but it was. If something like that happens, grab your camera as well as guns so you can substantiate that it WAS the dog that did the damage. I feel so sorry for your daughter. I never got over the loss of those lambs. To this day I have a difficult time loving dogs. Hope your daughter does well. Encourage her to start again and help her to do so. Don't focus on the negative if you can avoid it. She will take lots of her cues from you. Very sorry for your loss.