YOU SAID:

Kate's back hurts because of a horse

INTO JAPANESE

ケイトのために馬の背中が痛い

BACK INTO ENGLISH

Kate for the horse's back hurts

INTO JAPANESE

ケイトに馬の背中が痛い

BACK INTO ENGLISH

Kate is the horse's back hurts

INTO JAPANESE

ケイトは馬の背中が痛い

BACK INTO ENGLISH

Kate is the horse's back hurts