Show sheen stain remover and whitener?

I'm going to a show in the end of July and i know my horse WILL NOT stay clean over night before the show. I'm trying to find something that works for stain removing on a horse. I came across Show Sheen Stain Remover And Whitener, but I'm completely confused with it though. Is this actually for horses? With it bleach my chestnut horse because of the whitener? How well will it work and how do you use it? Thanks in advance!