Oil of oregano is great at getting rid of mange (actually it's one of those "miracle cures" for almost anything)! Tea tree oil is another good one.
This may sound a bit extreme, but I know back in "the day," they used to poor WD-40 on the dogs to get rid of mange. My husband's uncle bred hunting dogs -- he always had atleast a dozen of them, and every now and then he'd have a dog have an outbreak, and he'd take it, poor WD-40 on it and tie it to a tree away from the other dogs. Within two days the mange would be gone.
Before the war, they used motor oil.
I think it may be for the same reason they always tell us to put vaseline in our hair if we have lice -- it suffocates them, plus makes it hard for anything to hold on to. So while I don't recommend using WD-40 (LOL) it makes sense that the oil of oregano or tea-tree oil might work just as well. Back when we used all-natural products to get rid of dog lice (at my work -- and eventually we did resort to chemicals, just way better results) we used coconut based natural laundry detergent -- apparently coconut is somewhat anti-parasitic. Perhaps if you rub coconut oil on Glacier that might help too -- I think it would be suffocatign and slippery enough, plus still have the antiparastic effects.
But seriously I would try the oil of oregano too -- it's magical!