Bryan so sorry that happened. I've certainly had my share back in the day. A prolapse uterus is not always all that difficult to replac. Especially if you can get the animal standing. Of course the earlier after it happens the better. Warm water and a mild disinfectant to clean. Then your fist up the middle being careful not to punch through the uterine wall, the cervix is tough, the uterus itself is soft. But use a non irritating lube or mild soap if you have non. Clean and gently keep working it in with one arm up the middle and the other hard stuffing it in around the edges. Get it started and keep at it just holding when she strains and working it in more in between. Eventually it will just flop right back in. If you can, sew up the outer vagina with a wide ribbon type thread. Heck I've seen it done with sterilized twine. But leave the bottom open for urination. Cut those ties out in a day or two. One the uterus shrinks down it is safe.
If she won't stand you have to pull both legs back so she is Essentially on her knees. You will be fighting a very difficult battle if she is lying down.
It's a lot worse thinking about than doing
Of course putting her in the freezer asap is a good alternative as well.