Orcs should be capable of riding wargs without a saddle. This averts the issue of either having lots of saddles available in the early game, or restricting the amount of warg-riding orcs in the early game to avoid having lots of saddles around.

Gnolls should be able to generate riding leocrottas.

When you cause a monster’s mount to become scared, there is a chance that the rider gets thrown off, possibly taking some damage. This also happens to the player if their steed gets scared.