I know this suggestion sounds pretty absurd, but here I go..
Know the trouble of mounts falling to death? I suggest a solution..
Horseshoes! They would be crafted by putting 4 iron ingots, one in each corner of the crafting grid. Horses (possibly hoofed mounts in general) would now gain a new slot for horseshoes. If the horseshoes are inserted into the slot, the horse will gain +2 protection.
But one may ask, how does it help agianst falling?
They can be reforged or modified, but they can only gain thicksoled, strongshod or lightfooted modifiers, which protect agianst falling.
A possible evil alternative to this would be warg claw-covers (I really can't think of a better name..). They would be applied for the horseshoes slot for wargs, but instead of decreasing fall damage, they would buff the attack damage of the warg. Unmodified would be +2? They could be modified with melee weapon damage buffs (sharp, keen, mighty, legendary). They'd be crafted with the same pattern as horseshoes, but with orc steel on any orcish crafting table. They'd offer the warg no protection.
I dont think horseshoes should give pritection
Instead, jungle mud, podzol, barren dirt and other sludgy materials would all slow down horses, but with horseshoes the horses would recieve no speed penalty