As Jack and Pat sat together, Jack felt an uncomfortable itching. He reached reached down and scratched his crotch, not realizing the hair there had begun to change.
"Yeah, why don't we give them a little?" Jack grinned at the suggestion. Standing up, Pat grabbed the jar, ready to give the horses some. Jack, however, started scratching all over as fine hairs started growing over his body. Pat noticed his actions.
"Are you okay, master?" She asked.
"Yeah, I....." Jack broke off as he noticed his dick. It had changed shape and color to a deep red, and a white sheath was starting to grow, attaching to his abdomen. Rubbing a hand across it made him moan. "I....it's fur....." He grabbed the bottle and looked at it. He noticed some small words he hadn't seen before "sexual activity with the subject will cause changes in humans......"