I tried many times the borax and hydrogen peroxide on my very large german shephard. I found it helped but never cured and also was very difficult to apply to a large dog. Also i believe if I heal him from within it would be a long term solution. From what i read mange is due to w eakened system allowing the mites that are there anyway, but in very small numbers, to multiply into an infectious state.
By giving him all raw meat and bones and occasionally putting in shredded carrot and egg in his food, it helped. But what has finally done it is putting MSM powder in his food an drinking water. It is such a relief after struggling with this problem for around a year. i had seen two vets and got products sent from overseas. But the diet and the MSM is definitely the answer. It overall creates a healthier dog anyway. It is to me the only way, as washes and chemicals dont change the enviroment internally that let it happen initially