This weekend I encountered a kind of kinky female equine transformation story from a very unexpected source... the long-running NPR series
This American Life.
Amy Bonnaffons' story Horse follows a woman who voluntarily undergoes a medical procedure to gradually transform into a horse, and it goes into some detail about the process of it and her emotions. It's read by two actresses, one telling the story and another reading excerpts from a brochure about the horse-ifying process. Equine transformation isn't quite my thing, but I know that for some of you this story will go down like sugar cubes after a nice long gallop. It starts at about 34 minutes into the episode.
I'm not sure, but this story may be just an excerpt from a longer work. Bonnaffons has a collection of short stories out soon, and apparently many of them deal with transformations of various kinds.