If mange is the culprit, as jaybay has already said, ivermectin is the treatment of choice. Like with griselfulvin, though,
ivermectin is not without its risks,
and, depending upon what breed or breeds make up the dog's genotype, ivermectin can be extremely dangerous to use on them. The dogs that ivermectin can be dangerous for are collies, and any breeds that were developed by mixing collies with other dogs.