Why can't horses vomit? I know that they cant puke, but I have never really thought about why. So what is the real reasoning, anotomy, science, whatever behind this? Just a random question, but it has me curious!

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.

Horses have a band of muscle around the esophagus as it enters the stomach. This band operates in horses much as in humans: as a one-way valve. Food freely passes down the esophagus into the stomach as the valve relaxes but the valve squeezes down the opening and cuts off the passage for food going back up.

It's just the way they're built. They can't breathe through their mouth either, so I guess it's physically impossible for them to puke. Kind of a set back, eh?

For two reasons. One is that horses do not have the capacity for reverse peristalsis in the esophagus such as humans do. Peristalsis is a wavelike muscular constriction and shortening of a tubular organ that moves content along. In horses it only works to move food toward the stomach. In humans it can work in reverse to regurgitate food or vomitus back toward the mouth. Pets Questions and AnswersPets Questions and Answers


The other reason is because the more acute angle of the joint of the esophagus with the stomach and the thickness and sustained constriction of the sphincter muscle at the stomach entry prevents regurgitation of stomach contents back into the esophagus. A sphincter muscle is circular and it constricts to close off an opening.

The cardiac sphincter regulates passage of food into the stomach. In humans the cardiac sphincter will relax to allow stomach contents to be vomited, but in horses the cardiac sphincter acts as a one way valve, since it only relaxes when food is present in the esophagus and being moved into the stomach.

So when humans vomit, the sphincter relaxes and reverse peristalsis in the esophagus brings stomach contents back up and out through the mouth, which can't happen in horses. Some horses are born with anatomic aberration that allows some backflow of food into the esophagus, but it isn't common.

Add....when food becomes lodged in a horse's esophagus, it is called choke. It is not the same thing as choke in humans, which occurs when the trachea is obstructed. When you see food coming out through the nostrils of a horse, this is not vomiting. This happens with choke, as back pressure and spasming in the esophagus forces trapped food to enter the nasal cavity and to be coughed out through the mouth.

Registered Nurse and 57 years with horses

Horses are unlike cows. Cows have four-chambered stomachs, which allows them to "throw up" their cud and chew it again, because their stomachs can't digest it as well as a horse. A horse's stomach is a lot like ours, it gets the job done, and done well. The muscles in a horse's neck are stronger than ours, which makes it difficult for a horse to vomit, as well as the fact that they have a valve closer to their stomach that is "one way," unlike us.

It is very rare, but horses can and do vomit. They never survive for long afterwards.,

Experience