Can Horses Throw Up? Why It’s Impossible (and What to Do)

Can horses throw up? It is one of the most common questions horse owners ask, especially after seeing feed, saliva, or fluid coming from their horse’s mouth or nostrils. While humans, dogs, and many other animals throw up to clear their stomachs, a horse’s digestive system is strictly a one-way path.

Why Can’t Horses Throw Up?

The answer lies in the unique design of the equine digestive system. Unlike humans, dogs, and many other mammals, a horse’s esophagus and stomach are structured for one-way movement, carrying food from the mouth toward the stomach while strongly resisting backward flow. As described in Equine Surgery by Auer and Stick, several anatomical features of the gastroesophageal junction (including the powerful cardiac sphincter and the angled entry of the esophagus into the stomach) make vomiting extremely difficult in horses.

1. A Powerful Lower Esophageal Sphincter

The primary barrier is a thick ring of muscle called the lower esophageal sphincter (or cardiac sphincter), located where the esophagus meets the stomach.

In animals capable of vomiting, this muscle relaxes on cue to let stomach contents travel upward. In horses, however, it acts as a heavy-duty one-way valve that remains firmly locked, preventing backward movement even when pressure inside the stomach reaches dangerous levels.

2. A Sharp Angle of Entry

The structural entry point provides a second physical seal. Rather than connecting in a straight line, the esophagus meets the stomach at a steep, sharp angle.

As the stomach fills, it expands against this junction, creating a natural mechanism that clamps the entry even tighter. Combined with the strong cardiac sphincter, this structural lock ensures stomach contents stay trapped where they belong.

3. A Disabled Vomiting Reflex

Vomiting isn’t just stomach pressure – it requires a complex neural reflex involving the brain, diaphragm, abdominal muscles, and esophageal sphincters working in tandem.

Horses lack the coordinated neurological sequence required for reverse peristalsis. Even if severe abdominal contractions occur, the lower esophageal sphincter fails to receive the signal to relax, meaning stomach contents cannot be expelled through the mouth.

4. A Small Stomach Built for Constant Grazing

Because horses evolved to graze continuously on small amounts of forage, their stomach is relatively small and relies on continuous movement into the intestines rather than long-term storage.

The downside of this design is an inability to relieve sudden pressure. If gas or fluid accumulates due to colic or gastric reflux, a horse cannot naturally empty its stomach, placing them at severe risk of gastric rupture.

5. The Diaphragm Provides Another Physical Barrier

In many animals, powerful contractions of the diaphragm and abdominal muscles help generate the pressure needed for vomiting. In horses, the stomach sits deep within the rib cage and fits tightly against the diaphragm. Combined with the horse’s unique digestive anatomy, this positioning further limits the ability to force stomach contents back into the esophagus.

An anatomical illustration breaking down why horses can’t throw up versus animals that can!

Can Horses Regurgitate?

Although many people use the terms vomiting, and regurgitation interchangeably, they describe different processes. While horses cannot vomit stomach contents, they can regurgitate material trapped in the esophagus or upper throat. Understanding the difference between the two helps pinpoint where the underlying issue is located:

Choke: The Most Common Condition Mistaken for Vomiting

Choke is by far the most common reason owners think their horse is vomiting. Unlike true vomiting, choke is an obstruction of the esophagus rather than the stomach. Feed, saliva, and water become trapped behind the blockage and may drain back through the mouth or nostrils before they ever reach the stomach. To many owners, this can look as though the horse is throwing up, but what they are seeing is actually regurgitated material from the esophagus. Because choke can quickly lead to dehydration, aspiration pneumonia, and injury to the esophagus, it should always be treated as a veterinary emergency.

Why True Vomiting Is a Veterinary Emergency

True vomiting is considered an exceptional event in horses. In the landmark paper Inquiry into the Reasons why the Horse Rarely Vomits, researchers analyzed documented cases to determine the diseases responsible when horses did vomit. Rather than occurring as a normal protective reflex, vomiting was associated with advanced gastrointestinal disease that created extreme pressure within the stomach. The principal conditions identified are summarized below.

Primary and Secondary Gastric Dilation

Gastric dilation occurs when the stomach becomes excessively distended with feed, fluid, or gas. Primary gastric dilation is usually caused by rapid overeating or feeds that expand after ingestion, whereas secondary gastric dilation develops when an obstruction farther down the intestinal tract prevents stomach contents from moving normally.

Because horses cannot vomit to relieve the pressure, the stomach continues to stretch. Without rapid veterinary treatment to decompress the stomach and address the underlying cause, gastric rupture can occur.

Severe Colic and Intestinal Obstruction

Some of the most life-threatening forms of colic including strangulating obstructions, intestinal volvulus (twisted intestine), impactions, and intussusception can also lead to severe gastric distension.

Although the blockage may occur well beyond the stomach, digestive fluids continue to be produced. As these fluids back up through the gastrointestinal tract, pressure inside the stomach rises rapidly. This is why veterinarians often pass a nasogastric tube in horses with severe colic to remove accumulated gastric fluid before the stomach reaches a critical point.

Post-Operative Ileus

Post-operative ileus is a complication that can develop after abdominal surgery when the intestines temporarily stop moving normally. Instead of progressing through the digestive tract, fluid accumulates within the stomach and small intestine, resulting in gastric reflux and increasing stomach pressure.

Careful monitoring and repeated gastric decompression are often required until normal intestinal function returns.

Why Gastric Rupture Is More Common Than True Vomiting in Horses

By the time a horse develops enough pressure to force stomach contents backward, the situation has already become critical. In most cases, the lower esophageal sphincter remains tightly sealed, so the stomach wall fails before the one-way valve opens. As a result, gastric rupture is far more common than true vomiting in horses experiencing severe gastric distension.

Gastric Rupture (The Most Common Outcome)

When pressure inside the stomach exceeds what the stomach wall can withstand, the stomach may tear. Once this happens, feed, stomach acid, bacteria, and digestive fluid spill into the abdominal cavity.

This rapidly causes peritonitis, a severe inflammation and infection of the abdominal lining, followed by endotoxic shock as bacterial toxins enter the bloodstream. Unfortunately, gastric rupture carries an extremely poor prognosis, and most affected horses do not survive despite intensive treatment.

Rare True Vomiting and Aspiration Pneumonia

In exceptional circumstances, stomach pressure becomes so extreme that it mechanically forces open the lower esophageal sphincter. This is not a normal vomiting reflex but rather a mechanical failure of the stomach’s protective barriers.

Because horses lack the coordinated neurological reflexes that normally protect the airway during vomiting, stomach contents can be inhaled into the lungs instead of being expelled safely. This can result in aspiration pneumonia, a severe lung infection that further complicates an already life-threatening gastrointestinal emergency.

Cascading pathways of acute gastric distention.(PATH A) Gastric distention triggers the gastric reflex, forcing the lower esophageal sphincter (LES) open and leading to emesis and secondary aspiration pneumonia as shown in (2A). (PATH B) More commonly, severe intragastric pressure leads to gastric rupture, culminating in fatal peritonitis and endotoxic shock (2B).

What Should You Do If Your Horse Appears to Be Vomiting?

If your horse appears to be vomiting, don’t assume it’s a simple stomach upset. Whether the material is coming from the esophagus (such as with choke) or, in the rarest cases, from the stomach, your horse should be treated as a veterinary emergency until proven otherwise.

1. Contact Your Veterinarian Immediately

Feed, saliva, or fluid coming from the mouth or nostrils is not normal in horses. Early veterinary assessment is essential because conditions such as choke, severe colic, or gastric reflux can worsen rapidly.

2. Remove Feed Immediately

Take away hay, grain, and treats to prevent additional material from entering the esophagus or stomach. Unless your veterinarian advises otherwise, avoid offering more feed until your horse has been examined.

3. Keep Your Horse Calm

Minimize stress and avoid unnecessary movement. If your horse is showing signs of colic, follow your veterinarian’s instructions regarding walking or confinement rather than forcing exercise.

4. Don’t Try to Treat It Yourself

Do not attempt to pass a hose or tube down your horse’s throat or give medications unless directed by your veterinarian. Improper treatment can worsen an esophageal obstruction or increase the risk of aspiration.

5. Watch for Other Warning Signs

While waiting for your veterinarian, note any additional symptoms, including:

• Feed or saliva draining from the nostrils
• Repeated swallowing or coughing
• Neck stretching or repeated attempts to swallow
• Severe abdominal pain, rolling, or pawing
• Heavy sweating or signs of shock

These observations can help your veterinarian determine whether the problem is more consistent with choke, severe colic, gastric reflux, or another emergency.

How Veterinarians Diagnose the Cause

Because horses cannot normally vomit, a veterinarian’s first priority is determining where the material is coming from. Feed and saliva draining from the nostrils usually point toward an esophageal problem such as choke, whereas fluid originating from the stomach may indicate gastric reflux or another life-threatening gastrointestinal emergency.

The diagnostic process typically includes:

Physical Examination

Your veterinarian will begin with a thorough physical examination, checking your horse’s heart rate, temperature, hydration, abdominal sounds, and signs of pain. They’ll also ask when the problem started, what your horse was eating, and whether colic signs developed before the episode.

Passing a Nasogastric Tube

A nasogastric tube is one of the most valuable diagnostic tools in horses with suspected choke or severe colic. If an esophageal obstruction is present, the tube may identify where the blockage is located. If large volumes of fluid are recovered from the stomach, it suggests gastric reflux, indicating that digestive contents are not moving normally through the intestines.

Endoscopy

If choke is suspected or the esophagus may have been damaged, your veterinarian may perform an endoscopic examination. A flexible camera allows direct visualization of the esophagus to identify obstructions, inflammation, ulcers, or injuries that are not visible during a routine examination.

Additional Tests

Depending on your horse’s condition, further diagnostics such as blood tests, abdominal ultrasound, or abdominal fluid analysis may be recommended to evaluate severe colic, intestinal obstruction, infection, or other underlying diseases.

Identifying the source of the problem is critical because a horse that appears to be vomiting may require very different treatment depending on whether the disease involves the esophagus, stomach, or intestines.

Treatment Depends on the Underlying Cause

There is no single treatment for a horse that appears to be vomiting. Management depends entirely on the underlying cause, which is why an accurate diagnosis is essential before treatment begins. The following overview reflects current recommendations from the American Association of Equine Practitioners (AAEP) and the Merck Veterinary Manual. The original references are provided in the Sources section below.

Early treatment greatly improves the chances of a successful outcome, particularly for choke, which often resolves without long-term complications when treated promptly. In contrast, conditions associated with gastric reflux or true vomiting usually indicate severe gastrointestinal disease and require immediate veterinary intervention. Delaying treatment increases the risk of life-threatening complications such as gastric rupture, peritonitis, or endotoxic shock.

Can These Emergencies Be Prevented?

While not every case can be prevented, good feeding and management practices can reduce the risk of choke, certain forms of colic, and other digestive disorders that may cause a horse to appear to be vomiting. The following recommendations reflect current guidance from the American Association of Equine Practitioners (AAEP) and the Merck Veterinary Manual. See the Sources section below for the original references.

• Soak feeds that expand with water, such as beet pulp, according to the manufacturer’s instructions.
• Introduce dietary changes gradually to give the digestive system and gut microbes time to adapt.
• Provide unlimited access to clean, fresh water to help reduce the risk of dehydration and impaction colic.
• Feed smaller, more frequent meals rather than large grain meals whenever possible.
• Schedule regular dental examinations, as poor dentition can interfere with chewing and increase the risk of choke.
• Maintain an effective parasite control program based on your veterinarian’s recommendations, particularly for young horses.
• Monitor horses closely after abdominal surgery, since post-operative ileus and gastric reflux require early recognition and treatment.
• Learn the early signs of choke and colic and contact your veterinarian promptly rather than waiting to see if the problem resolves on its own.

Although these measures cannot eliminate every emergency, they can help reduce the risk of serious digestive disease and improve the chances of a successful outcome through early recognition and prompt veterinary care.