Horses would probably be dead or endangered if they were more trouble than they were worth.

The entire way their legs and hoofs are built. They’d have paws with massive claws and massive legs. They’d run more like a big cats.

Man I wish we had shittywatercolour here to draw this up.

Carnivorous Ungulates did exist in the past

Large animals that were difficult or costly to domesticate (like the Aurochs) were generally just wiped out.
My guess is if horses were carnivores they would be extinct or limited to a few in zoos and some of the wilder places (like tigers).

We would be riding cows instead.

Please send help. 🧠