Shave the hair and use super rash cream. It softens the scabs so you can peel them off. Then use something with and antibiotic and fungicide once the scabs are gone.
Pig oil and sulphur, you won't have shave off the hair if you use this.
Shave the hair off. You need to remove ask the scabs and clean the area daily. I find Desitin diaper cream to work wonders at clearing it up and softening the scabs. Good luck!
My mare has it. I shave her legs so she has no feathers. It was the only way I could get them under control.