The man's penis retreated back into his body and formed into the black leathery lips of a mare's vagina. He cried out as his body started to form into a mare's body before it turned into a loud whinny as the last of his clothes fell away torn to bits. A stall door opened seemingly on its own and Harry, drawn by the scent of a new mare trotted forward and mounted the would-be thief.
You couldn't watch anymore and turned back to your feed as the sound of whinnies and neighs filled the stable. Maybe he deserved it, he had tried to steal from the Zoo after all, but it did seem a little extreme. You started eating again finding yourself hungry as the sounds finally faded away.
When you looked back at the transformed man you saw that he, now she, was having her mane brushed by the new attendant as he lead her into a stall down the row from you.
"Good girl, you got your first transformation done without a problem," the attendant said and patted you on the nose. "I knew you could do it. A shame that she's now a mare, but that's justice for you given that he wanted to use you for breeding."
Of course that was what the Zoo wanted to use me for but that wasn't the point. The first attendant came back in a few minutes later pulling a couple of horses that you figured was probably the couple she had been talking with before behind her.
"We had a bit of a problem, but one of your new mares dealt with it," the male attendant said to her as she put the couple in adjoining stalls and they nuzzled each other. "It seems that someone wanted to try and steal another horse."
"This is getting to be a problem," she said with a shake of her head before she looked at you and at the new mare. "Well, we have two new mares, and I think our new friend here is due for a reward. Maybe you won't have to wait as long as I was thinking to be bred."
You whinnied and sighed a little, well, there was nothing you could do. You just lowered your head, resigned to your new fate.