I have tried almost everything. The ranch owner told us that we need to wash her butt with Head and Shoulders every week. I've done it for almost two months and nothing happened. Then she said her skin was TOO dry so to do this whole two part method bla bah thing. We did that for almost a month and it still didn't work. The only thing that semi worked at all was hand sanitizer and furizone. That got her hair growing back again, but she rubbed it out again. MTG isn't working either. We even treated for mites and nothing happened. Now she just sits in her corral, butt-hair-less untill I can figure out something else. She never did this when she was in an actual pipe corral. The vet should be coming out within a month for our preventative care program, she needs her shots and teeth done. Untill then, I need some help! Anything you suggest will be tried out! Lol.
Onto pictures.

Lawdy, lawdy... It looks worse now than it ever has. These pictures are from december.
Please, and thank you SO much! BTW, she is UTD on dewormer. It's just her shots that I need because apparently, they were UTD, too. But now I'm not sure because her previous owner was a liar. Okay, I'm done! Haha