request for stallion castration story

you can give me any stallion castration story or write a story according to this summary,

a girl gets a feral stallion for gift(it can be a stallion transformed from a man or a normal stallion). she rides the stallion for racing. how she discovers her horse has movement problem in the hind legs. after she consults her coach, her coach discovers that the horse's big balls are hindering him. the stallion also has attitude problems and gets frisky around mares. her coach advises her to geld him. however, the girl is insistent on keeping a stallion. but under repeated inconvenient situations created by the stallion, the girl finally decides to geld him.

'it's better if the surgery is detailed.'