Horses have a band of muscle across the esophagus as it enters the abdomen. This band operates in horses as much as it operates in us: as a one-way valve. Meals freely passes down the esophagus into the abdomen because the valve relaxes but the valve squeezes down the opening and cuts off the passage for meals going again up.
Horses, nonetheless, differ from and their valve actually works. People can vomit. Horses virtually cannot do this due to the ability of the cut-off valve muscle. Additionally, the esophagus meets the abdomen at an angle which boosts the cut-off operate when the horse’s abdomen is bloated with meals or fuel. Then the abdomen wall pushes towards the valve, closing the esophagus much more fully from the abdomen. Usually, the mechanics are such that the horse’s abdomen ruptures earlier than the valve yields.
If materials does go from abdomen out the esophagus, the horse could possibly die from these. That is why horses cannot vomit. However, there are rare cases that they do, but so rare and that’s for sure.