I know that it's chancey but I've had luck with clearasil (or a 10% Benzoyl Peroxide zit cream) on white ponies(in fact I only use it on white ponies). Use with caution though, it fades stains, but you must not put it on the symbols! I acidentally faded a small patch of the symbol on one of mine by getting clearasil on it. It wasn't bad but it was noticable.