As Mike stood over the fallen stallion, he noticed that the horse's scent was starting to change. Curious, he dropped his head and inhaled, curling his upper lip to trap the odor. This smelled good. He felt himself getting sroused, and realized why.
The stallion had lost the battle, and was paying the same price Mike would have paid. He was becoming a mare. As the change sped up, the old male's wounds healed, and his appearance altered. The old scars vanished, and as the former stallion stood, he finished changing into a much younger mare!
Mike was surprised. Losing made the old horse young and healthy again? But as his body responded to the new mare's needs, Mike realized more than just the sex and age had altered. The stallion ahd shown human intelligence before - now whoever had been the stallion was a completely normal horese, thinking horse thoughts.
That was disturbing - because Mike now had to battle new stallions and win, or face the same fate. However, right now he was more interested in finding out what it meant to be a stallion. Instincts were taking control, and he slid up over the mare's rump and thrust his flared shaft deep into her.