My yorkie does not have it but about 6 months ago, my collie had a bought of demodetic mange. Just a small area. It started clearing up on it's own. Collie's can't have the normal medications to treat it so I did nothing. I recently put her on a prey model raw diet and am hoping that has boosted her immune system. We have seen no reaccurance and she is doing better than ever for an 11 year old dog with arthritis.
I would research that alternative. You probably won't get an ok from your vet as many vets are still leary about a raw diet but I would research it and see where that leads you. Good luck!