Like the show, the author of Equestria: A History Revealed seems to love any kind of pun, ranging from horse related puns, to any kind of pun that can be mustered. If there's a word that can be substituted for a horse pun, you can bet it'll be used. Not even the bibliography is exempt from this. The sources are chockfilled with bad puns too.
"Ravished by civil wars up the ass (no pun intended, the deciding battle was fought on Donkey Doodle Peak), and saddled with the responsibility of repairing the broken nation, the new griffon government desperately needed supplies and help."