Ty whinnied in pain. Bretman's equine dick was so huge it was tearing him apart. He arched his neck and could see that Bretman was a fucking Clydesdale and from his glances at his own slender legs and lean sides, Ty was pretty sure he was an Arabian or some other kind of race horse. He wished that he was better designed to accommodate the intruding horse member. The smell of stallions and mares was overwhelming, he was thinking clearly.
Suddenly, the pain changed. Bretmon's dick was still pounding away, but somehow Ty had changed. He was actually feeling pleasure with the huge Stallion lying across Ty's hind quarters and back. Ty arched back his neck in ecstacy, and then as he orgasmed, Ty's head dropped forward. As Ty's head swung between his forelegs, he twisted his neck, and was startled to see that his formerly huge equine equipment was missing. Had he become a gelding? No, worse. He saw the teats of a mare swelling on his underside. No wonder it didn't hurt anymore, Ty's accommodation had changed Ty into a mare!
Oh, well. Ty didn't care, he decided to enjoy the ride.