Mistress Jane wanted to try riding an old human horse. So she climbed it and she whipped it and it carried her for a few minutes before it got tired. She did not let it go. Rather, she got it to carry her some more by whipping it. It was fun for her but an absolute nightmare for the human horse which had to endure pain and torture as she did her thing.
Lady Alisha's pony doesn't want to behave like a pony should do. He always tries to speak and communicate like a human telling her that he is not a horse! That's something she absolutely cannot deal with. A slave is whatever she tell it what it has to be. In this case it's a horse or a pony and she punishes him for his misbehave by slapping him until he understands...