Well donkeys are kinda implied to exist as-is in the world of Umamusume, as seen in the Town Musicians of Bremen depicted in the 2022 Yasuda Kinen promo art. IIRC Fuji Kiseki also said something once to the effect of "Are those ears of yours the ears of an umamusume or a donkey?"
Heyyya, Mac-chan!Wha—Welp, one of my fans is involved with the zoo business, y'see.Howdy.How could you ride such a thing?