Thanks so much for your replies--all of them.
I do want to clear a few things up. Paisley did not just turn on my dad and bite him. The two dogs were in a the middle of a fight and my dad, not knowing dogs, stuck his hand in between them. In actuality, we are not sure which dog "got" him, but assumed it was Paisley because Lola's jaws are tiny and probably couldn't do the damage that was done.
It was at that point that I knew there was some dog-on-dog aggression and fed them in separate rooms. Lola would always wait until she could hear Paisley start to eat before she would start to eat her own food.
When this did first happened, I did try to find a home for Lola since she was non-aggressive, cute, and still very young, but no one wanted a dog and I could never, ever turn her over to a shelter. I felt, at that time, that Paisley would be fine as a solo dog. Things seemed to settle out for a long while after this point and there was only one other, small incident with the toy. I used my foot to stop the fight and neither of the dogs tried to bite me.
I know many people have it black and white in their mind what they would do in this situation, but I do not and never have. It is not easy, at all, for me to put a dog down. If the dog has shown aggression to people with no reason, then I would agree that it is necessary, but so far, this doesn't seem to be the case.
Believe me, though, I am really beating myself up now for this. I should have tried harder to place Lola. But I guess none of that matters now. I just guess I was wanting so bad for it to be okay because I love both of them.
Paisley is back from the vet now (not my vet) and the vet said that the wound does not seem to be consistent with a dog-fight wound but was some weird tear. We have look all over the yard and cannot find the torn skin (and it is very good-sized). At the corner of my fence, the chicken wire has been chewed down and pulled (or pushed back). On the outside of my fence in the same area, there is blood. So either my small Lola was injured and tried to stick her head through and got blood on the outside of the fence (don't know how that would happen without blood on the inside) or something on the outside of the fence was bleeding. Paisley is too big to get anything through the slats of the fence.
We do have Red Foxes in this area and they are all over the place right now, but I can't say I've ever seen them trotting around at 11:00 a.m. That would seem highly unlikely.
I guess I'm just never going to know what happened. The worst part is is that I'm such a softie over animals. I'm 42 years old and I've never forgotten when my bunny rabbit was killed (when I was 12) in my backyard. It still haunts me.
I'm so afraid that I'm never going to be able to get today's images out of my mind. And will my last memory of Lola always be that she is dying in my arrms.