I have had luck with cleaning the hot spot and cutting away hair, then applying a mixture of cortisone cream mixed with Neosporin w/PAIN RELIEF.
After applying, we watch her closely for about 1/2 hour, by then the Neosporin has numbed the area and then we put a sock or gauze pad on. Usually have to do this 2-3x a day. The cortisone helps heal and the Neosporin relieves itching. Works pretty good unless hot spot is severe and it is amazing how quickly they can get bad. Good luck