Sorry for the double post, but Rich just found the following:
Treatments vary according to the type of mite you're looking at.
- Organophosphate insecticides
- Lime-sulphur solutions
Of course, topical Rx are more fast-acting and will target the specific area. Whatever you think is the specific area, expand that area by about 12" all around to make sure you kill the mites that might be hanging around the outer edge.
Again, I suggest talking to your BO, tack shop person, or vet to get the right formula.
Ryle might have something else to say if she comes online...