Here is what it says in the AQHA rules about English equipment. I think they are being short-sighted but whatever...

137
e) Saddles must be black and/or brown leather of traditional
hunting or forward seat type, knee insert on the skirt is optional.
Saddle pads should fit size and shape, except when necessary to
accommodate numbers on both sides, for which a square pad or suit-
able attachment may be used. Saddle pads and attachments shall be
white or natural color with no ornamentation.