
My Rotties get these, if we spot them early...
shave/clip the area, so the air can get to it, clean with a dilution of hipiscrub (available at vets or boots), and then spray with Daktarin athletes foot spray. Dries out in a couple of days.
First time we encountered this our girl was in kennels, and it took a further 2/3 weeks of vets appointments and fuciderm cream before it started to heal. I got the tip about the daktarin from Champdogs, and it works a treat.