Why can't horses vomit?

The muscle that acts like a one-way valve where the esophagus connects to the stomach actually does its job, unlike in humans where it can let food travel the opposite direction, back to the mouth. Another reason that horses can not vomit is because the esophagus is connected to the stomach at an angle where it is forced shut when the horses stomach bloats. This can cause colic when the horses stomach bloats, and untreated, the stomach will rupture and the horse will die.