The Curious Case: Why Horses Can’t Throw Up Explained

One memorable incident in my career as a veterinarian involved a horse that was showing signs of severe gastrointestinal distress. The horse was restless, agitated, and appeared to be in pain. As I examined the horse and reviewed its medical history, I quickly realized that the issue was related to its inability to throw up.

The horse had ingested a large amount of toxic plant material, which would typically be expelled through vomiting in other animals. However, due to the horse’s unique physiology, this was not possible. Recognizing the urgency of the situation, we immediately administered appropriate treatments to help the horse pass the toxic material through its system safely.

This incident served as a powerful reminder of the importance of understanding the intricacies of each animal’s physiology and how their unique traits can impact their health. It also highlighted the need for specialized care and quick decision-making in critical situations involving horses and their inability to throw up.

Why Can’t Horses Throw Up

Horses can’t throw up or vomit because of the way their stomachs and digestive system are built. They have a strong muscular valve called the lower esophageal sphincter, which acts like a one-way door. It allows food and water to go into the stomach but stops anything from coming back up.

Horses have smaller stomachs as compared to their large body size, and their shape makes it difficult for them to vomit. The esophagus (the tube that connects the mouth to the stomach) enters the stomach at an angle, making it harder for things to come back up.

This might seem strange to us, as humans can vomit when we’re sick or have eaten something bad. But for horses, not being able to vomit is actually a good thing. They have a unique way of digesting food called hindgut fermentation. It involves helpful bacteria breaking down plant material in their cecum and colon, which is essential for their health.

If horses could vomit, it would interfere with this delicate digestive process and could make them very sick. So, while not being able to throw up might seem odd, it’s a crucial part of how horses stay healthy and digest their food properly. However, it’s essential to keep an eye on their health and quickly get help from a vet if they show signs of stomach problems like colic.

The Role of Stomach and Why Horses Can’t Vomit

The stomach plays a crucial role in the digestion of food. When we eat, food travels down the esophagus and enters the stomach, where it is mixed with gastric juices. These juices contain enzymes and acids that start breaking down the food into smaller particles, making it easier for the body to absorb nutrients.

For most animals, including humans, the stomach has a built-in defense mechanism to protect against harmful substances. If we eat something toxic or spoiled, our body can quickly expel it through vomiting. Vomiting is a forceful expulsion of stomach contents back up through the esophagus and out of the mouth.

However, horses are unique in this regard. They cannot vomit due to the structure of their digestive system. That is because of two main reasons:

Strong Lower Esophageal Sphincter (LES): 

Horses have a powerful muscular valve at the bottom of their esophagus known as the lower esophageal sphincter. This valve remains tightly closed after food enters the stomach, preventing it from flowing back up the esophagus. In contrast, in animals that can vomit, this sphincter can relax and open, allowing stomach contents to be expelled when necessary.

Stomach Shape and Size: 

Horses have relatively small stomachs compared to their large size and unique digestive system. Additionally, the entrance of the esophagus into the stomach is at an angle, making it difficult for stomach contents to move in the opposite direction.

This inability to vomit is essential for horses because they are “hindgut fermenters.” They rely on a specialized microbial fermentation process in their cecum and colon to break down fibrous plant material from their diet. If horses could vomit, it would disrupt this delicate digestive balance and lead to severe health issues.

So, while it might seem strange that horses can’t vomit like humans, it’s a critical adaptation that helps them efficiently digest their food and maintain their overall well-being. However, it also means that horse owners and caretakers need to be vigilant about their animals’ health and seek prompt veterinary attention if they show signs of digestive problems, such as colic.

How Mighty Sphincter Prevents Horses from Vomiting

The mighty sphincter, also known as the lower esophageal sphincter (LES), is a muscular valve located at the bottom end of a horse’s esophagus, where it connects to the stomach. This sphincter plays a crucial role in preventing horses from vomiting or throwing up.

When a horse eats, food travels down the esophagus and reaches the stomach. The LES acts as a powerful gatekeeper that regulates the movement of food between the esophagus and the stomach. Once food passes through the LES and enters the stomach, the sphincter contracts and becomes tightly closed.

This tight closure serves two primary purposes:

Preventing backward flow: 

The primary function of the LES is to prevent stomach contents from flowing backward into the esophagus. This is crucial because stomach acid is highly acidic and could damage the delicate lining of the esophagus if it were to flow in the wrong direction. The LES acts like a one-way door, allowing food and liquids to enter the stomach but preventing them from going back up.

Preserving hindgut fermentation: 

Horses are herbivores and rely on a unique digestive system called hindgut fermentation to break down fibrous plant material effectively. The microbial fermentation process takes place in the cecum and colon of the horse’s digestive tract. If a horse were able to vomit, it could disrupt this critical fermentation process by regurgitating partially digested food from the stomach, potentially causing digestive issues.

The powerful nature of the LES is what sets horses apart from many other animals, including humans, who have the ability to vomit. While vomiting is a helpful defense mechanism for getting rid of harmful substances, it is not compatible with the hindgut fermentation process that is vital for a horse’s digestion.

By having a strong and tightly closed LES, horses can efficiently digest their food, maintain their unique digestive process, and avoid potential complications from stomach acid flowing in the wrong direction. However, it also means that horse owners and caretakers need to be attentive to their animals’ health and quickly address any digestive problems that may arise.

Other Factors

The lower esophageal sphincter (LES) is the primary factor that prevents horses from vomiting, but there are also other anatomical and physiological factors that contribute to this unique ability:

Stomach size and shape: 

Horses have relatively small stomachs compared to their large body size. The size and shape of the equine stomach make it challenging for them to expel stomach contents through vomiting. The entrance of the esophagus into the stomach is at an angle, which further inhibits the backward flow of stomach contents.

Powerful muscles: 

Horses have strong and muscular walls in their stomachs and esophagus. These powerful muscles aid in the process of moving food down the esophagus and into the stomach. However, they also play a role in preventing the reverse flow of stomach contents.

One-way peristalsis: 

Peristalsis is a rhythmic contraction and relaxation of muscles that helps propel food through the digestive system. In horses, the peristaltic contractions of the esophagus are unidirectional, meaning they only move food downward, not upward. This further ensures that stomach contents stay in the stomach and do not move back up the esophagus.

Lack of a diaphragm reflex: 

In many animals, including humans, vomiting is triggered by a reflex involving the diaphragm and abdominal muscles. However, horses lack this specific reflex, which is another reason why they cannot vomit.

These factors, in combination with the strong LES, make horses highly resistant to vomiting. While not being able to vomit is essential for their unique digestive process and overall health, it also means that they cannot use this mechanism to expel harmful substances from their stomachs. As a result, horse owners and caretakers must be vigilant about their horses’ diet and health to prevent ingestion of toxic or harmful materials and promptly address any signs of digestive issues.

Does Vomiting Serve a Purpose?

Vomiting serves a vital purpose in many animals, including humans. It is a protective mechanism used by the body to expel harmful substances, spoiled or toxic food, or any ingested material that could be dangerous. 

Vomiting helps prevent the absorption of harmful substances and protects the digestive system from potential damage. It is an essential defense mechanism to maintain overall health and well-being.

What Happens When Horses Can’t Vomit?

When horses can’t vomit, it means that they lack the ability to expel stomach contents through their mouths. Instead, their powerful lower esophageal sphincter (LES) and unique stomach anatomy prevent any backward flow of food and digestive fluids. 

While this adaptation is essential for their specialized hindgut fermentation process, it also means that horses cannot utilize vomiting as a defense mechanism against harmful substances in their stomachs.

What Does It Means If A Horse Is Throwing Up?

If a horse appears to be throwing up or regurgitating material, it is a cause for serious concern. Horses physiologically cannot vomit, so any observed attempt to do so may indicate a life-threatening condition. It is essential to seek immediate veterinary attention if a horse is showing signs of throwing up, as it could be a sign of a severe medical issue.


Choke is a condition in horses where food becomes lodged in the esophagus, leading to difficulty swallowing and potentially respiratory distress. Unlike vomiting, choke is not the regurgitation of stomach contents, but rather the obstruction of the esophagus. The choke requires prompt veterinary intervention to remove the blockage and prevent further complications.

Spontaneous Gastric Reflux

Spontaneous gastric reflux is a condition that can occur in horses, leading to the backward flow of stomach contents into the esophagus. Unlike vomiting, which is a forceful expulsion, gastric reflux is a passive flow of stomach contents due to abnormal relaxation of the LES. This condition can lead to esophageal irritation and discomfort for the horse.

How Many Stomachs Does a Horse Have?

Contrary to a common misconception, horses do not have multiple stomachs like ruminants (such as cows). Horses have a single stomach, but their unique digestive system is designed to efficiently digest fibrous plant material through hindgut fermentation.

What Do the Most Digestive Disturbances Result From in Horses?

Most digestive disturbances in horses result from factors like sudden changes in diet, overeating, consuming spoiled or toxic food, lack of access to fresh water, and feeding management issues. These disturbances can lead to conditions like colic and gastrointestinal upset, which can be serious and require veterinary attention.

Can a Horse Regurgitate?

No, horses cannot regurgitate in the way that some other animals can. The powerful lower esophageal sphincter prevents any backward flow of stomach contents, making regurgitation impossible for horses.

What Happens if a Horse Throws Up?

As horses physiologically cannot vomit, the scenario of a horse throwing up is very rare and would be a sign of a severe medical problem requiring immediate veterinary attention.

Will a Horse Die if It Throws Up

It is highly likely that a horse would die if it throws up. Horses are unable to vomit due to the powerful lower esophageal sphincter (LES) and unique stomach anatomy, which prevents the backward flow of stomach contents. 

If a horse attempts to vomit forcefully, the pressure built up in the stomach and esophagus can cause serious and potentially life-threatening complications, including rupture of the esophagus, aspiration of stomach contents into the lungs, and damage to the digestive system. Immediate veterinary attention is crucial if a horse shows signs of attempting to vomit, as it indicates a severe medical emergency.

How Do You Settle a Horse’s Stomach?

To help settle a horse’s stomach and support digestive health, it’s essential to maintain a consistent and balanced diet, avoid sudden changes in feed, ensure access to clean and fresh water, and provide regular exercise. Any signs of digestive disturbances, such as colic or choking, should be addressed promptly by a veterinarian.

How Horses Adapted to Survive Without Vomiting

Horses have adapted to survive without vomiting by developing a strong lower esophageal sphincter (LES) and a unique stomach shape that prevents the backward flow of stomach contents. This adaptation is crucial for their hindgut fermentation process, which enables them to efficiently digest fibrous plant material.

The Risks of  Horse’s Inability to Vomit.

The inability to vomit can be both an advantage and a risk for horses. While it protects their hindgut fermentation and digestive process, it also means they cannot expel harmful substances from their stomachs through vomiting. This makes horses more susceptible to digestive disturbances like colic and requires vigilant management of their diet and health.

Why Can’t Horses Burp or Vomit

Horses cannot burp or vomit primarily due to their powerful lower esophageal sphincter (LES) and stomach anatomy. The LES prevents any backward flow of stomach contents, and the unique stomach shape makes it challenging for gas or stomach contents to move in the opposite direction.


Overeating is a common issue in horses and can lead to various digestive problems, such as colic and choking. Since horses cannot vomit, overeating can put them at a higher risk of stomach distension and discomfort.

What Other Animals Can’t Throw Up

Aside from horses, certain other animals, such as rabbits and rats, are also unable to vomit due to their unique digestive physiology and stomach anatomy.


Horses cannot vomit due to the powerful lower esophageal sphincter (LES) and unique stomach anatomy, which prevents the backward flow of stomach contents. While this adaptation protects their hindgut fermentation process, it also means they cannot use vomiting as a protective mechanism.

Horses are susceptible to digestive disturbances like colic and choking, so proper feeding management and prompt veterinary attention are crucial to maintaining their digestive health.


Can horses burp?

Horses cannot burp due to the structure of their digestive system and strong lower esophageal sphincter (LES).

How do you get gas out of the horse?

To help a horse expel gas, encourage exercise, and provide access to fresh water and forage.

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