In fairly sure armor for horses were used in that era, as joker said, with advances in weaponry armor for horses became a must. And guns weren't common enough to make armored horses obsolete. The cataphracts of the Byzantines and the teutonic knights used barding a lot, a simple cloth protects against an arrow a lot more than nothing. They did have lighter cavalry for speed which had no barding, I know the winged hussars (when are these guys from again? 1500s I think) didn't use barding and they had huge armor. I guess it depends heavily on place and time.