Seeing how both us and birds can vomit, probably. I imagine that developed very early. If you eat something harmful, you’re dead if you can’t vomit. If you don’t have the brainpower to identify safe and harmful things, you’re pretty screwed.
Horses are probably the single most fucked up animal on the planet, with maybe the sole exception of Przewaski’s horse. Seriously we fucked them up so badly, like im pretty sure if every dog was a badly fucked up as horses they would be a hybrid of American bulldogs, Bull terriers, and chihuahuas.
This is to say never use a horse as a barometer for anything when it comes to standard functions.