Horses Cannot Vomit At All

The digestive system of a horse (Review) is a remarkable, and sometimes perilous, one-way street. This is primarily due to an incredibly powerful muscular ring, the cardiac sphincter, located where the esophagus meets the stomach. This biological valve clamps shut with such immense force that it effectively prevents any backward flow of food or gas. The sharp angle at which the esophagus connects to the stomach further reinforces this one-way system, making regurgitation a physical impossibility for the animal.

This unique anatomy is why colic, a general term for abdominal pain, is so life-threatening for equines. When gas, fluid, or an impaction builds up, a horse has no simple release valve to relieve the mounting pressure. The cardiac sphincter is so unyielding that the stomach wall will stretch to its limit and can even rupture before the muscle allows any contents to be expelled. This catastrophic event is often fatal, highlighting a critical vulnerability in an otherwise resilient animal and necessitating immediate veterinary intervention to manually relieve the pressure.