CAUTION: This story is nothing at all like the happy sex romps that I usualy write. The young woman doesn't feel too unhappy now, but things may get a lot worse for her.
Madame Top Hat, as she was known to her associates, happily watched the new ponygirl in training as she strutted on the treadmill. The trainee was tall and young and beautiful, with chestnut hair and a clear complexion. She was also blessed with large, natural breasts and a sexily plump belly that flared nicely into voluptuous hips and ass and legs. The new ponygirl was just the kind that a lucky owner would want for personal sexual use or for breeding and, judging from her youth and looks and the way she was strutting, she would make an excellent show pony. She was big and strong enough to be strictly a cart pony too, but that would seem to be a waste of her other good qualities.
Of course, before she could become any of those things, any spirit of rebelliousness or disobedience had to be eliminated, and she had to be trained, which was the job of Madame Top Hat. How the trainee had come under the power of her and her associates was not something that concerned her. Judging from her youth and intelligence, the trainer thought she might have formerly been a student at the nearby university, but she would never bother to find out. In fact, she didn't want to know any personal information about any ponygirls or their backgrounds, not even their former names. They were no more than raw material, brought to Madame Top Hat to be transformed from girls into ponygirls. The trainer was good at her job, and well-paid, and never had any personal opinions or feelings of empathy that might prevent her from doing the best job possible. When Madame Top Hat spoke to her charges, if she used any form of address at all, it would be "Pony", and never anything else that might lead the trainees to believe that they were still human.
That was the first day of the new ponygirl's captivity and instruction. She would spend seven days in the warehouse that Madame Top Hat's group leased, undergoing preliminary training and being evaluated. The only physical changes to be made there had already been done or were in progress. While the trainee was still unconscious from the chloroform, her nipples had been pierced and the large steel rings inserted. This had to be done early in the process so the piercings would heal and could be treated if they became infected. The rings were necessary because, once the field and cart phase began, her reins would sometimes be fastened to them. That phase would take place at the advanced training facility, which was located on a ranch, hundreds of miles away in a remote part of the state. It had to be remote because the training was mostly done outside, and had to be kept from the view of nosy persons. .
The only other physical change, using a butt plug with an attached tail to expand the pony's ass, was also underway. The plug being used was one of those kept in the supply inventory to be inserted into trainees, and would almost certainly not remain with her after she had been auctioned off. Once her sale was accomplished, the ponygirl's new owners would decide what kind of tail, if any, they wanted her to have. Until then, the butt plug would usually be held snugly in place by ropes that were wrapped, both horizontally and vertically, around the pony's body. Another length of that same cordage securely held her arms behind her back. The latter piece of rope would never be untied, remaining in place for the entire training period, right up to the time of her sale, and even after that if the new owners so desired. The tail, however, would be removed for a half an hour a day to give the ponygirl a chance to defecate into the designated place in her stall. After she had emptied her bowels, her body and the stall would be hosed down with warm water, followed by re-insertion of the butt plug.
The only other change to her body would be the unobtrusive tattoo of the logo of the association, and that would be done just before crating her so she could be trucked to the place where she and other ponygirls, from that facility and others, would be offered at auction. Other changes, such as additional piercings or branding or shaving the pony's cunt or trimming her hair into a mane would also be options of the new owners.