I realise this is an old post but thought I would add from our personal experience. One of our billy kids was badly beaten up by the rest of the gang, stamped on and kicked around and was unable to stand at all. Appeared to have neurological damage, possibly even a broken back.
However, he was such a character that we resisted the temptation to pull the plug. He was eating well, just couldn't stand up and urinated and pooed where he was. Got quite smelly so we had to wash him several times. He was in a small pen next to other goats so seemed contented and relaxed. Stayed like that for 3 months, then due to a rearrangement in the shed he ended up in a much bigger pen for a time. Within 2 days he stood up (and promptly fell over again) but continued to try. We deliberately put his food the other side of the pen and he would get to his feet and wobble over to it to eat. Spent more and more time on his feet, getting better and stronger and more stable. Took him down to a pen in the garden where he proceeded to demolish the hedge over a period of days.
He was sheared a few weeks ago and looks much better, he walks confidently (and even tries to run!) and we are even starting to think about introducing some girls in the autumn. It took a long time for the inflammation to go down, muscles to regain strength and possibly even learning to walk again if there was nerve damage, but I think moving him to the bigger pen was the key move. With more space he had more motivation to move whereas in a small pen it wasn't worth the effort.
Just a simple (psychological) thing to try.