well they have camels too... so donkeys and zebras might be possible...
Donkeys and zebras AFAIA still exist in the Uma-verse. It's just the Equus caballus species that became anime girls and none of the other members of the Equus genus followed suit.
That's a... ♡... SE-CRE-T.
Uma is dieting...
Oh right, what is a rodeo machine supposed to be again?