Vasculitis Disease

My horse Cherokee had swelling in her rear legs and this pussy stuff was coming out. I thought that she may have been kicked. When the vet came out she said it may be vasculitis. Does anyone know anything about this. My vet put her on a steroid and it seemed to get worse so she had to come back out and put her on an antibiotic and an ulcer medication for all the medication she was on.. most of it has cleared up at this point she still has some edema but nothing like it was.

Why is this in the gaited horse section? o.O

So it IS getting better then? Worse?