There's a tool for grooming horses called a "sweat scrapper" for a reason. :) If you ever watch a horse race or any other time a horse is working hard and fast

There's a tool for grooming horses called a "sweat scrapper" for a reason. :) If you ever watch a horse race or any other time a horse is working hard and fast, you'll see white foam near where the reins touch the horse's neck and and anywhere else there's friction. That's frothed up sweat.