I found this among a lot of MLP accessories but I don't think it's actual pony wear. It looks like it could be Barbie to me but I don't know. Anyone have a clue??
From all the Barbie horse I have seen I don't think it is but it might be from a Disney princess horse or a Barbie pony. This is only from what I know I know I could be wrong. It does look familier.