It took me a moment.
Via Arbroath.
It seems this is photoshopped. The girl in the picture is Amber Amputee ( http://profile.myspace.com/index.cfm?fuseaction=user.viewProfile&friendID=124049594 ). A version of the picture without the horse: http://www.tshirthell.com/images/contestpics/a517_019.jpg, the horse picture: http://www.sewerhorse.com/.