Look for bleach in pen form
Oxi clean and hydrogen peroxide work wonders on whites!
Get some washing detergent and add some water until it turns into a paste. Rub it on the stained spot and let it stil for 30 minutes to an hour. Fill a sink with warm water and add washing detergent. Put the saddle pad in the water and let it soak again for 30 minutes to an hour then wash it normally. It's a long process but ita works for me. Hope this helps.