Read down on the ebay article it says it's made with Genuine leather (I think it mentions Horse Hide).
It says "horse butt facsimile pillow." "Facsimile" being the operative word.
It also says "Hand Painted Leather sculpture" It says it's a 'soft sculpture.' I doubt Horsehide from the rear of a horse would be 'soft.'
It does say that it's made with genuine leather but it doesn't say that it's made with genuine horsehide leather. I would think THAT would be a selling point if asking $125 for a small pillow.
The leather for horse butt doesn't come from the area on the back of the leg next to the tail as seen in the pillow. It comes from the skin that covers the sides of the rear legs. This can be seen in the illustrations of the horsehide leather cuts on
http://horween.com/index.php/leathers/ under 'Equine Hide Shapes.'
It does, however, talk of using an authentic horsehair tail.
I suppose the only real way to be sure would be to ask the woman who is making them. I'll send off an e-mail and find out for sure.
Stitchawl