My son and DIL have a pup that had cutaneous vasculitis. The vet who initially saw her did not know what it was but put her on steroids, which did help. She put her on prednisone for one week. My son and DIL went out of town and left her with me for a weekend right when she had been tapered off of the prednisone. She immediately started up again...I was horrified. She had this large open wound on her belly...and other areas erupting. Rushed her to my vet who immediately knew what it was. She put her on prednisone for 30 days...said that is what is needed...longer term treatment. She cleared up...she does have some scarring, but is fine now.
Hers was attributed to vaccines.