Why can't horses vomit?

Answer 1

They can, actually. The act of regurgitation is very, very similar to vomiting, except that it is a much less forceful, somewhat more "passive" process where food from the foregut is brought up--albeit gently--into the mouth to be chewed as cud. Vomiting is much more forceful, and usually an ominous sign in cattle signifying acute gastric distention issues, however it is rare to see a bovine vomit--same with horses.

Answer 2

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.

Answer 3

No, but calves can (those that are younger than three to four months of age) because they don't have a fully developed rumen and rely on the abomasum for their primary digestion of foods like milk.

However, some may argue that the way cattle get a bolus of partially digested feed to come up to be rechewed is considered throwing up or vomiting. But vomiting and regurgitation, though they are different words that mean similar things, are only just that--similar: Vomiting or throwing up refers to the act of ejecting one's stomach contents through the mouth (and can often be violent), not bringing them up, which is the definition of regurgitation. Thus, it is safe to say that no, cows don't throw up as in the context of vomiting, but they do regurgitate in order to chew partially digested forage.

Answer 4

Rabbits have an extremely strong valve between the esophagus and the stomach; overpowering that valve in order to send food out of the stomach is nearly impossible.