Ivermectin is being used in the US to treat demodex, BUT ONLY AS A LAST RESORT IN CASES UNRESPONSIVE TO MITABAN. It must be given in extremely high doses on a daily basis for a period of about 6 weeks and could be toxic and/or fatal to some animals at this dose range.
For all breeders info, this is the current recommendation of the board-certified dermoids on demodex:
If you have a potential/future breeding animal that has demodex, DO NOT DIP.
Alter diet to optimum, use Vitamin E supplement, treat secondary staph infection, make sure pup or dog is current on vaccinations, intestinal parasite free and in the best possible health. Let the dog's immune system rid itself of the mite. If it does, this animal is fine to breed from. If it does not clear on its own then the animal should not be used as breeding stock. They wait out these cases with great patience and most of them will self cure. If they don't they really should not be used as breeding stock.