"Stalled," by MC
The other thing that is appealing (to me) about bestialization fantasies is the idea of long-term bondage / objectification / dehumanization. Overnight. Days. Weeks. Months. Forever.
Whenever I fantasize about being a pony-boy (which is not so often, really), this is the sort of image that comes to mind. Not being out on the track, the center of attention, but being left alone in my stable, for hours on end, looking forward to a visit from the groom, or a chance to play in the yard with the other ponies. Perhaps I am moved from one farm to another; no one ever tells me what’s going on. Why would they?
I think this is part of the appeal of latex fetishism as well, for lots of folks. And certainly chastity. It is weirdly paradoxical, since these are precisely the kinks that are most difficult to sustain for any long period of time.