I usually am not impressed by products. . . Some do their job okay, and other do not even work, but this one product, MTG - See below
Shapley's Original M-T-G™ - Skin & Coat Care
Worked great for rain rot on a Arab rescue I had. It also helps with scars, fly bites, etc. . . It is a GREAT all around product that you don't have to use over and over to see results from.
I mixed in iodine or a triple antiboiotic with it as well, and her condition was greatly improved in a week.
See before and afters on lucasfarmwv.com under rescue work