Some artists forget a fact that horses would fold their ears backwards when they're angry/upset. This detail didn't go unnoticed by the Uma Musume creators.

GeloKaiser said:

Some artists forget a fact that horses would fold their ears backwards when they're angry/upset. This detail didn't go unnoticed by the Uma Musume creators.

As exemplified by Twin Turbo in a Sakazaki Freddy comic in post #5679878. And made easier to see thanks to the distinctive 'air intakes' marks on Turbo's ears.