Well, I'm hoping for no big. I got all the way out to the ranch and realized I'd made a mistake and bought the leather waterproofing. Decided touse it anyway.
I hope it won't ruin the blanket, make my horse's hair fall out, anything like that. Anyone been there, done that?
If your blanket is still under any warranty it it's voided using anything other than the mfg's recommendations. Most likely your horse will be fine, I think the wash won't hurt the blanket. Leather washes are typically pretty gentle.