The witch forced Jake to drink her transformation potion. He twisted away and spluttered, leaving most of the liquid on the ground of his cage but it was fine for the witch. Only a few drops swallowed sufficed. She backed away, smiling and admiring her work.
Quickly, Jake felt woozy. He barely had the time to ask what the witch had made him swallow before he fell to the ground and into a deep sleep. It was better considering the transformation he was going to go through. His body would have to suffer a lot of alterations. The witch had decided to transform Jake into a centaur. The mane and hair of centaurs were very useful in potion preparations and they could do a lot of tasks. Hard-working creatures, they were. Of course, Jake would have to be convinced a bit for that part but the witch had a few tricks up her sleeve. She could have changed him into a female centaur but she would rather use mating on a female captive. Adjusting to a centaur life would be difficult enough for the youngster without adding a sex change to boot.
Jake's transformation was quick. His hair color remained the same, as the witch had seen no need to change that. His tail would have the same color and his coat a bit of a lighter hue. His muscles would remain the same too. He'd work on that later on his own. The changes thus affected his lower body. His pelvis grew two new legs and elongated. His backside grew extra bones to accommodate a tail. His stomach expended into his new equine body, as well as longer intestines. His feet fused into hooves and his ankles shot upwards. His backbone increased tremendously. His genitals were now out of reach of Jake's hands, being below the hindquarters of his new equine anatomy. It would be normal equine reproductive organs. The witch cared not about these details, of course, but it made the transformation easier and it made the males transformed happier. Until the realised that touching themselves was near impossible because of the sheer length of their own bodies and became as frustrated as horses in heat. And that they had a sheath concealing said penis. But Jake would figure that part out for himself later. She admired the now full centaur snoring in his cage. Time to change the lad's cage to a more appropriate enclosure. He would rouse in a few hours.