The horse’s digestive system is large, complex and sensitive to change. Horses evolved over millenia to efficiently extract nutrients from fibrous plant material, grazing on grasses and other roughage for the majority of the day.

The horse’s gastrointestinal anatomy, digestive function and microbial population are all optimized to break down fibrous forages and absorb enough energy to meet the needs of these free-roaming, athletic animals.

This is a key reason why deviating from the horse’s natural diet and feeding pattern can lead to disruptions in digestive health, potentially resulting in colic, gastric ulcers, or gut dysbiosis.

Horse owners can help prevent gut problems in their horses by making management choices that support the horse’s natural foraging behavior and gut physiology. Continue reading to learn more about how the horse’s digestive system works and what you can do to keep it functioning at its best.

The Horse’s Digestive Anatomy

The horse’s digestive system has two parts: the foregut and the hindgut.

The foregut consists of the mouth, esophagus, stomach, and small intestine. Digestion of proteins, fats and hydrolyzable carbohydrates (such as those found in grain) takes place mainly in the foregut.

The powerhouse of the horse’s digestive system is the hindgut, which consists of the cecum, colon, and rectum. It is here that structural carbohydrates (such as those found in stemmy grasses) are digested and waste products are eliminated from the body.

Horse Digestive Tract - Hindgut & Foregut

The Foregut

The foregut consists of the mouth, esophagus, stomach, and small intestine. The stomach and small intestine are responsible for digestion of proteins, fats, and hydrolyzable carbohydrates (sometimes referred to as non-structural carbohydrates or NSC). [1][2]

Mouth

The structures and secretions of the mouth that are involved in feed intake and digestion include the: [1]

  • Lips
  • Teeth
  • Tongue
  • Saliva

All of the parts of the mouth work together to take in food, chew it, moisten it, and move it along to the ensuing structures of the digestive system. [1]

Lips

The lips of the horse are flexible and sensitive to touch and temperature. [1] They are adapted to feel surfaces to identify food. Horse lips are somewhat dexterous; they grasp and pull food into the mouth, towards the teeth, where it is ripped up and taken in for chewing and digestion. [1]

Unlike other animals such as cats and dogs who must lap water into their mouths, the horse’s lips are adapted to work in tandem with the tongue to create negative pressure inside the mouth. This allows them to draw water into their mouths. [1]

Teeth

While other grazing animals such as cows use their tongues to tear up plants, the horse uses its teeth to chew forages. This allows for tougher plant matter to be sheared from its base and consumed. [5]

A horse’s teeth are categorized as either incisors or molars. The incisors are sharp, spade-shaped teeth found at the front of the mouth. They grasp and shear plants and other foodstuffs, beginning the action of cutting large pieces into smaller sections. [1]

The molars are wide and flat and are found along the sides of the mouth. They are used for grinding food into a swallowable ball often referred to as a bolus or ingesta, once combined with water and digestive secretions. [1]

The grinding surfaces of a horse’s molars are made of different compounds called enamel, dentin, and cementum. Each of these materials has a different hardness and wears away at different rates. [1]

This composition ensures that the molars of the horse remain deeply ridged throughout its lifetime instead of being worn down to a smooth surface. The ridges are necessary for chewing to ensure food is well ground before it proceeds past the mouth. [1]

However, grinding tough fibrous feed makes horse’s teeth susceptible to developing sharp edges, which is why ongoing dental care is a fundamental cornerstone of equine management. [1]

Horses are hypsodonts, which means their teeth continue to erupt from the gumline until approximately 17 years of age. [14]

The teeth need to be kept in good working order to optimize digestion. Plants in the equine diet that contain structural carbohydrates need to be broken down sufficiently through chewing to make their contents available for fermentation further down the gastrointestinal tract. [2][15]

Tongue

The horse’s tongue is a strong and dexterous muscle that pushes food towards the molars for grinding and eventually towards the back of the throat where it is swallowed. Along with the lips, the tongue also draws water into the mouth for consumption. [1]

Salivary Glands

As this bolus is chewed in the mouth, salivary glands in the horse’s mouth add saliva to the mix. [1]

Unlike other mammals, the horse’s saliva does not contain much amylase, which is an enzyme that breaks down starch to release sugars. Instead, equine saliva primarily serves to moisten and lubricate the bolus, making it easier to swallow. [1][6]

A horse’s saliva also contains bicarbonate and saline, which neutralize acids contained in the food and stomach. [1][3]

Once the bolus is sufficiently chewed and moistened, the tongue sends it to the back of the mouth where it is swallowed. [1]

The preceding actions of gathering and chewing food are within the horse’s voluntary control. From the point of swallowing forward, the horse’s parasympathetic nervous system takes over and digestive function is involuntary. [1]

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The Digestive Tract

Once swallowed, the bolus enters the digestive tract, which is most simply described as a very long tube made of several structures including the esophagus, stomach, intestine, cecum, colon, and rectum. [1][5]

This tube is comprised of two layers of muscle. [1] In the first layer, the muscle fibers are wrapped around the tube, and their contraction works to narrow and dilate the tube’s diameter. In the second layer, the muscle fibers run parallel to the tube. Contractions in this layer extend and contract the tube laterally. [1]

The actions of these muscular layers allow for two types of contraction: [1]

  • Peristaltic contractions, which move the food through the system
  • Mixing contractions, which churn the food around to ensure that there is a thorough mixture of food, microorganisms, enzymes, and chemicals to digest food and effectively extract nutrients

The Esophagus

Once the food leaves the mouth, it enters the esophagus. The esophagus is a muscular tube connecting the mouth to the stomach, running parallel to the horse’s spine. [7]

The esophagus’ main function is to transport food from mouth to stomach. [1] The esophagus expands as food moves through it, then contracts to push food towards the stomach. [1][2]

The esophagus is closed off at the mouth end by the glottis and the soft palate, which swings open to let food pass through while preventing any foreign matter from entering the lungs. [1]

Similarly, at the stomach end, the gastroesophageal sphincter prevents solids and stomach acid from entering the esophagus. [1]

If the horse swallows too much fibrous food or if food is not chewed sufficiently, it can get lodged in the horse’s esophagus. This is known as choke. [6] Other factors contributing to choke include insufficient water intake, dental disease, and low saliva secretion. [6]

Can Horses Vomit?

The morphology (structure) and angle of the junction between the esophagus and the stomach make it very difficult for equines to vomit. [1][7]

Horses do have a vomiting reflex which will trigger contraction of the stomach and abdominal muscles. The horse may show signs of colic pain due to this contraction. However, they will not be able to push digesta out past the gastroesophageal sphincter and the continued pressure on the stomach can cause gastric rupture in severe cases. [1]

Horses with severe gastric distention need to be treated by a veterinarian to relieve pressure, reduce pain, and prevent gastric rupture. [7]

 

The Stomach

From the esophagus, the bolus enters the stomach. The stomach is a muscular bag that sits between the horse’s esophagus and small intestine, protected by the ribcage. [1]

Horses are monogastric animals, and their stomach has a single compartment. Other species, like ruminants, camelids, and cervids have multi-compartment stomachs. [6] Unlike ruminants, the horse’s stomach does not have a substantial population of microorganisms.

This means the horse’s stomach is not designed to break down structural carbohydrates, such as cellulose and hemicellulose, found in forages. Instead, these carbohydrates are fermented by microbes in the horse’s hindgut. [2]

The horse’s stomach is also relatively small for its body size and has a limited ability to expand within the abdominal cavity. [1][2] These attributes make the horse well-adapted to trickle feeding, or taking in small amounts of food over the course of many hours. [6]

Horses who take in too much food at one time, consume excess hydrolyzable carbohydrates in a single meal, or eat too quickly are susceptible to colic. [6]

Having a single-chamber stomach differentiates horses from animals such as goats, cows, or sheep, who are ruminants. Ruminants have a four-compartment stomach and they also regurgitate and chew food more than once (i.e. “chewing cud”). [2]

 

Glandular vs. Non-glandular Stomach

The horse’s stomach consists of a glandular region and a non-glandular region, also referred to as the squamous region.

The glandular region consists of cells that continuously secrete stomach acid and enzymes. [7] The stomach lining in this area is well protected from the harmful effects of stomach acid by a thick barrier of mucus. [7]

The non-glandular region of the stomach is less protected from stomach acid and is more susceptible to gastric ulcers. [6]

This area is particularly vulnerable when the horse’s stomach is empty; the horse continues to secrete stomach acid even in the absence of food, but there is a lack of saliva or food to buffer the acid and protect gastric tissue. [6]

Diagram of the Horse's StomachIllustration:

Digestion in the Stomach

The primary function of the stomach is to mix food with stomach acid and enzymes. These enzymes are responsible for the initial digestion of proteins, and to a lesser extent, fats and carbohydrates in the horse’s diet. [1]

Despite the low pH of the gastric juices, some microbes survive this environment and contribute to breaking down feed in the stomach. [16] The microbes in the stomach break down readily fermentable carbohydrates and produce acids such as lactate and volatile fatty acids (VFAs). [17] Grain feeding is associated with higher levels of lactate in the stomach, which may contribute to increased risk of gastric ulcers in horses fed high-grain diets. [18]

Gastric acids and enzymes in the stomach are unable to break down structural carbohydrates, such as cellulose and hemicellulose found in hay and grass. These structural carbohydrates are the horse’s primary source of energy and are fermented in the hindgut. [1][3][4]

Once the digesta is thoroughly mixed with stomach acid and enzymes, it exits the stomach through the pyloric sphincter and enters the small intestine. [1]

The Small Intestine

The small intestine is a long, muscular tube comprised of three contiguous parts: [7]

  • The duodenum
  • The jejunum
  • The ileum

Digesta is moved through the small intestine by contracting and relaxing muscles in peristaltic waves. [7]

The small intestine is the site of most nutrient absorption for proteins, fats, and hydrolyzable carbohydrates in the horse’s diet. [5]

The lining of the small intestine consists of finger-like projections called villi that increase the surface area available for absorption of nutrients. [1] Cells lining the small intestine secrete enzymes that breakdown these nutrients into smaller fragments that can be absorbed.

The length, flexibility, and mobility of the horse’s small intestine contribute to high risk factors of gut disorder in horses. Examples include: [7]

  • Volvulus: Twisting of the small intestine, potentially leading to obstruction
  • Incarceration: Parts of one intestinal structure get trapped in its own folds or the folds of another structure
  • Intussusception: A section of intestine telescopes inside itself

The small intestine is attached to the other structures of the body by the mesentery, which is a thin, fan-shaped tissue that loosely holds the structures in place while allowing slight movement within the abdominal cavity. The mesentery also contains blood vessels and nerves that supply various organs of digestion. [7]

The liver and pancreas are considered accessory organs for digestion. They aid in the process by secreting enzymes and other substances such as bile into the intestinal lumen to break down feed.

Nutrient Digestion in the Small Intestine

Table 1: Description of which nutrients are digested and absorbed within the small intestine.

Nutrient Digestive Enzymes End Products for Absorption
Protein
  • Proteases
  • Single amino acids
  • Dipeptides
  • Tripeptides
Fats
  • Lipases
  • Bile
  • Fatty acids
Hydrolyzable carbohydrates
(i.e. starches and sugars)
  • Amylase
  • Brush border disaccharidases
  • Monosaccharides

 

The Hindgut

Once the food has moved through the small intestine, it continues its journey through the last part of the ileum into the horse’s hindgut. [7] The hindgut of the horse consists of three structures: [7]

  • The cecum
  • The colon (large and small)
  • The rectum

Horses are hindgut fermenters. The majority (up to 70%) of the horse’s dietary energy comes from fermentation of structural carbohydrates (fiber) in the cecum and the colon. [1][5]

Hindgut Fermentation

The horse does not have the necessary enzymes to digest the fibrous part of plants in the stomach and small intestine. Instead, horses have a symbiotic relationship with microorganisms in the hindgut that do produce these necessary enzymes. [5]

Various microorganisms such as bacteria, protozoa, and fungi in the hindgut ferment structural carbohydrates in forages, converting them into volatile fatty acids (VFAs) and lactic acid. These acids are absorbed by the horse’s intestinal tissue, where they are picked up and circulated through the bloodstream as an energy source. [5]

Microbes in the hindgut also produce vitamin K and water-soluble B vitamins such as biotin. However, its in unclear how much of these can be absorbed in the horse’s hindgut. [7]

pH Balance

The pH level in the hindgut must be maintained above 6 to ensure a viable microbiome for effective fiber fermentation. In horses with healthy digestive systems, the pH is between 6.4 and 6.7. [2]

Horses with a pH lower than 6 are considered acidotic (too acidic), which can lead to proliferation of undesired microorganism and inadequate populations of desired ones. [2]

Microbiome

Imbalances in the gut microbiome increase the risk of osmotic diarrhea and endotoxemia, a serious condition characterized by the presence of bacterial endotoxins in the bloodstream. [2]

An inadequate or unbalanced diet can contribute to disruption in the equine gut microbiome, which can disrupt normal hindgut fermentation.

Insufficient fiber and too much starch and sugar are all contributing factors to hindgut fermentation dysfunction in horses. [5]

The Cecum

The first section of the hindgut is the cecum, which is a large, comma-shaped organ that can hold about 30 liters (7.9 gallons) of food and water and is one meter (3.3 feet) or longer. [7]

The cecum functions as a fermentation vat where microorganisms process carbohydrates and release byproducts, which are then absorbed by the horse. [1]

Microorganisms can also breakdown protein that has passed through the small intestine and use the amino acids for their own purposes.

Gravity pulls the bolus from the small intestine into the cecum. Contractions in the cecum churn the food and liquid from the tract, mixing them thoroughly with microorganisms to promote fermentation. [1]

After the ingesta is thoroughly mixed with microorganisms and digestion and fermentation are underway, peristaltic contractions move the ingesta towards the cecocolic orifice, which connects the cecum with the colon. [1]

Since the cecocolic orifice is relatively small, food that is not sufficiently broken down is in danger of getting stuck at this opening in the tract. [1] This is called an impaction and can happen at several locations within the gastrointestinal tract of the horse. [6]

The Colon

The horse’s colon, also known as the large intestine, is a long, muscular tube that can hold 80 liters (21 gallons) or more of food and water. [7]

In the colon, ingested food and water are further mixed with microorganisms, continuing the digestive process. Strong muscle contractions churn the ingested material to ensure thorough mixing with microorganisms. [1]

The colon absorbs volatile fatty acids released by microorganisms into the horse’s body where they are used immediately as an energy source or stored for future use. [2]

Water and electrolytes are also absorbed in the colon. However, these compounds are also partially secreted back into the intestinal lumen from the blood. This helps improve gut motility and prevent impactions. [7]

In addition, non-protein nitrogen such as urea enters the large intestinal lumen from the blood to be excreted in the feces. [7]

Journey Through the Colon

The colon is made up of two horseshoe shapes stacked one of top of the other. The “heels” of the horseshoes point towards the back of the horse on the left and the right of the body, while the curves that make up the “toes” point towards the head. [7]

The bottom horseshoe is referred to as the ventral colon, and the top one is referred to as dorsal colon. [1][3]

The right side of the ventral horseshoe is attached to the cecum by the cecocolic orifice and is positioned towards the hindquarters of the horse. [7]

Horse's Cecum and Colon - Digestive Anatomy

Right and Left Ventral Colon

After the cecocolic orifice, the right ventral colon curves towards the head on the right side of the body before curving at a gentle angle known as the sternal flexure. From there, the left ventral colon curves towards the hindquarters. [7]

After the left ventral colon, the colon makes a hairpin turn called the pelvic flexure.

At the pelvic flexure, the diameter of the colon changes drastically, narrowing from 25 cm (10 in) to 8 cm (3 in). [7] The change in diameter along with the very tight curve mean that this site in the tract is another common location of impaction. [6]

Left and Right Dorsal Colon

After the pelvic flexure, the colon travels back towards the head stacked on top of the previous horseshoe shape. The first part of the colon after the pelvic flexure is called the left dorsal colon. [7]

The curve at the toe of this upper horseshoe is known as the diaphragmatic flexure. [7]

After the diaphragmatic flexure, the part of the colon that travels back towards the hindquarters is known as the right dorsal colon. [7] Here, again, the diameter of the tube narrows as it approaches the transverse colon, making this another potential site for impaction. [1]

Final Stages of Digestion

Following the right dorsal colon, the digesta travels to the next structure: the transverse colon. [1] The main function of the transverse colon is to transport the digesta to the descending colon. [7]

The descending colon of the horse is a free-floating, looped, muscular tube that turns the bolus, which has been stripped of all absorbable nutrients, into fecal balls. [7]

This organ is segmented in a way that slows the passage of the food to draw as much moisture out of the feces as possible before it is eliminated from the horse’s body. [1]

The horse does a very good job of retaining a high proportion of the water it takes in. [1] When the fecal balls are formed and the water has been extracted, the colon moves the digested material into the rectum. [7]

The Rectum

The rectum is a relatively short, straight muscular tube. [1] The rectum widens at the end into a structure known as the rectal ampulla or the anal canal. [7]

The fecal balls move through the first part of the rectum and collect in the anal canal. Once sufficient fecal matter has collected in the anal canal, the pressure on the walls of the rectum signals to the horse’s brain to allow the anal sphincter to relax.

With that, the fecal balls are released from the horse, and digestion is complete. [7]

How to Support a Horse’s Digestive Health

The equine digestive system is finely tuned to process a diet rich in fibrous plant material. In the wild, horses graze on roughage for up to 16 hours daily.

When horses are fed in a manner that deviates from this natural grazing behavior, it can disrupt their digestive health, potentially leading to conditions such as impaction colic, gastric ulcers, or imbalances in the hindgut microbiome.

To safeguard against such issues, horse owners should prioritize management practices that align with the horse’s natural foraging behavior and digestive physiology. [8]

Feeding strategies that take into account the size and structure of the horse’s gastrointestinal tract, ideal pH balance, microbial population and importance of adequate hydration can optimize your horse’s long-term health and well being.

Effective management strategies for supporting the horse’s digestive system include: [4][5][8][12]

  1. Feeding a forage-first diet with adequate long-stemmed forages
  2. Feeding small, frequent meals and avoiding long periods without food
  3. Limiting the intake of grains to prevent hindgut disruption
  4. Ensuring adequate water supply and feeding salt to encourage hydration
  5. Providing your horse with adequate turnout to support gut motility
  6. Making dietary changes slowly to allow the microbiome to adapt
  7. Providing routine dental care to support chewing
  8. Conducting routine fecal egg count tests to check for parasites
  9. Feeding digestive supplements to maintain gut health

 

1) Feeding a Forage-Based Diet

Forages typically refer to the edible parts of plants other than separated grain, and include grasses and legumes that are common in the equine diet. [9]

Horses are expected to consume roughly 2 – 2.5% of their bodyweight in dry matter per day. [10] To support digestive health, the majority of this dry matter should be provided by forage. [8]

Based on this, a typical 500 kg (1100 lb) horse should consume approximately 10 kg (22 lbs) of hay per day. [8]

Feeding forage first helps maintain gut health by supplying fiber for hindgut microbes. Forage should be available at all times to mimic the horse’s natural feeding behavior, which involves consuming small meals throughout the day.

Domestic horses, particularly athletes, are often fed grains that are rich in non-structural carbohydrates to meet their high energy needs. [8] However, high-forage diets can reduce the risk of digestive issues like colic and gastric ulcers, even in cases where grains are considered necessary. [8]

Long-Stemmed Forages

Long-stemmed forages describe grasses and legumes that have not been processed into pellets or cubes, and that maintain their natural structure, cut no shorter than 2 inches (6 cm) in length. [4]

Feeding long-stemmed forages provides the type of structural carbohydrates that the horse’s digestive system is best adapted to ferment. This ensures the horse can efficiently produce volatile fatty acids, which are its main source of energy. [8] Long-stemmed forages also provide fiber for proper gut function, helping to prevent colic and other disorders. [4]

Horses are highly motivated to consume long-stem forages. Feeding large quantities of pelleted feed can alter a horse’s behavior, causing them to spend much less time eating and more time standing idle or searching for other fibrous material to chew. [19]

However, pelleted feeds or forages may necessary in some cases. For example, older horses, especially those with bad teeth, may need softer hay that is easier to chew, but it is still important to ensure adequate fiber intake for optimum health. [10]

2) Feeding Small, Frequent Meals

In the wild, horses graze continuously, which introduces a steady flow of saliva and food into their digestive systems. [8] This helps prevent gastric ulcers and best suits their small stomachs, reducing colic risk from feeding large grain-based meals.

In contrast, domestic working horses are often fed just two large meals daily. Although unavoidable for some operations, this practice can negatively impact gut health. [8]

Ulcers

Horses who are fed two daily meals have a higher risk of gastric ulcers. Intermittent feeding leaves the stomach empty and exposed to the continuous production of stomach acid. [8]

Feeding small, frequent meals of forage, provides a buffering effect so the average pH of the stomach remains above 4.0. This reduces the risk of ulcers from excess stomach acidity. [8]

Extending Access to Rationed Hay

The best way to mimic the horse’s natural feeding behavior is to provide free-choice access to forage. However, not all horses can have free-choice forage in their diet.

Horses that are overweight and are consuming calorie-dense forage such as immature grass hay may need to have their hay rationed to support healthy weight loss.

To avoid extended periods without access to forage, consider using a small hole hay net to slow down their intake. [11]

3) Limiting Grain Intake

Horses fed high-grain diets without enough long-stem forage are at risk of consuming excessive hydrolyzable carbohydrates. [5] This can lower the pH of the hindgut, leading to an imbalance of microorganisms and increasing the risk of acidosis, colic and gastric ulcers.

High-grain diets are also a contributing factor for behavioral problems and can increase the risk of laminitis, particularly in horses that are are insulin resistant. [8][9]

If forage is not sufficient to meet the energy needs of the horse, consider fat- and fiber-based energy sources instead of grains. [8] Soya hulls and beet pulp are low in starch and sugar, but high in readily fermentable fiber to supply energy through hindgut fermentation.

For those with high energy requirements, such as heavily exercising horses or lactating mares, consider adding oils, which are an energy-dense alternative to grains.

Rapid Hindgut Fermentation of Starch

Horses fed large amounts of grain in a single meal often experience hindgut dysfunction because the stomach and small intestine cannot breakdown all of the starch in the diet. The excess starch reaches the hindgut where it is rapidly broken down by microbes. [8]

Rapid fermentation of starch changes the hindgut pH, altering the balance of microorganisms. For this reason, the horse should be fed no more than one to two grams of starch per kilogram of bodyweight in any one meal. [8]

For a 500 kg (1100 lb) horse this translates to 1 – 2 kg (2 – 4 lb) of starch per day. Oats are approximately 40% starch so this would be between 2.5 and 5 kg (5.5 – 11 lb) of oats per day.

4) Ensuring Adequate Hydration

Water is one of the most important aspects of a horse’s diet, yet it is often overlooked. [3][4] Access to clean, fresh water is critical to support digestion and body temperature regulation. [4]

Horses that do not get enough water are at risk of dehydration, impaction colic and gastric ulcers. [4][20]

Feeding salt is also important to encourage water intake and ensures your horse’s sodium requirement is met. It is recommended to feed 1 – 2 ounces of salt per day and provide horses with loose, free-choice salt.

5) Providing Adequate Turnout

Turnout outside of the stall, whether on a dry lot or with pasture access, helps to mimic natural equine behaviors and supports gut health. Providing turnout can also enable social interaction and reduce stress in horses. [21]

Some studies, but not all, show reduced prevalence of gastric ulcers in horses with access to pasture. [22][23][24] This variability may be due to differences in fiber and hydrolyzable carbohydrate content of the pastures provided.

In one survey study, horses with some access to pasture had reduced risk of ulcers and this risk was further reduced when they were turned out with other horses. [25]

Pasture access has also been shown to alter the gut microbiome of horses which may impact their metabolism. [26][27][28]

Horses with metabolic syndrome still need turnout, but allowing pasture intake can increase their risk of laminitis. For these horses, turnout in a dry lot with appropriate hay can provide benefits without impacting metabolic health. Always consult your veterinarian and equine nutritionist about appropriate turnout for horses with metabolic syndrome or with a history of laminitis.

6) Making Dietary Changes Slowly

When a horse’s diet is changed too quickly, especially when introducing grains or concentrates, it can disrupt the hindgut microbiome. This can lead to digestive issues and an increased risk of colic. [8]

It’s recommended to make dietary changes gradually over the course of two to three weeks, mixing increasing amounts of new feed with the old.

Similarly, horses should be gradually introduced to fresh spring pasture, starting with one hour per day and increasing by 15 minutes incrementally to adjust from a hay-based diet to pasture.

7) Providing Routine Dental Care

Proper digestion begins with healthy teeth, which are crucial for adequately grinding feed. This chewing process reduces the size of plant material, increasing the surface area for enzymes to effectively break down nutrients. [5]

Horses with poor dental health are more likely to suffer from impaction colic and other gut issues. [10]

Regular dental care is essential, with yearly dental floating recommended for most horses. Older horses or those with specific dental problems may require more frequent examinations. [29]

8) Conducting Routine Examinations for Parasites

Parasites can also impact the horse’s digestive system, potentially causing malabsorption of nutrients, colic, impaction, and in severe cases death. [12]

Although it is impossible to keep a horse parasite-free, regular fecal testing and appropriate deworming protocols are important to maintain your horse’s digestive health. [12]

9) Feeding Supplements for Gut Health

After all other management and feeding strategies to support gut health are in place, you may want to consider adding a gut supplement to your feeding program. Depending on your horse’s unique needs, you can choose supplements that target the foregut, hindgut or both.

Antacids to neutralize stomach acid are popular for reducing the risk of gastric ulcers. However, maintaining an artificially elevated pH in the stomach can hinder the digestive process and can reduce the horse’s appetite. [30]

Instead, you can support your horse’s gut health by providing nutrients that promote the stomach’s natural defenses against ulcers. This includes the amino acid glutamine, a key energy source for cells in the digestive tract, and immune nucleotides, which aid in the rapid turnover of gut cells. [31][32][33][34]

To support hindgut health, consider adding probiotics, which are beneficial microbes added directly to the feed. These provide support for fiber fermentation on an ongoing basis. You may also want to provide prebiotics, which are nutrients that promote the growth of beneficial microbes in the hindgut.

Mad Barn’s Visceral+ is a gut health supplement designed to support the stomach, hindgut and immune system in horses. This pelleted supplement has a low feeding rate of 80 grams per day and does not include any grain fillers.

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Summary

The horse is a hindgut fermenter whose digestive system is adapted to a forage-based diet. Mimicking the horse’s natural eating pattern and diet composition can reduce the risk of gastrointestinal illness while optimizing digestion and overall gut health.

  • The foregut consists of the mouth, esophagus, stomach, and intestine. The stomach and small intestine are responsible for digesting proteins, fats, and non-structural carbohydrates in the horse’s diet.
  • The hindgut is the digestive powerhouse where structural carbohydrates are fermented by microbes. The hindgut is made up of the cecum, colon, and rectum.
  • Microorganisms and digestive enzymes are responsible for breaking down feed for absorption.
  • Feeding the horse a long-stemmed, forage-first diet with plenty of water, ensuring good dental health, and staying up to date on parasite control are effective strategies to keeping a horse’s digestive system healthy.
  • Hay and pasture alone will not meet all of the horse’s nutrient requirements. Provide a concentrated vitamin and mineral supplement to fully balance the diet.

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References

  1. Goff, J. P. Digestion Absorption and Metabolism, Dukes’ Physiology of Domestic Animals, 13th ed. Wiley-Blackwell, 2015.
  2. Hoffman, R. M. Carbohydrate Metabolism in Horses. Reviews in Veterinary Medicine, United States: International Veterinary Information Service, 2003.
  3. Julliand, V. and Grimm, P. Equine digestive microbiota: beneficial and detrimental effects to the horse?, in European Equine Health and Nutrition Congress, Utrecht, 2021.
  4. Nielsen, B. The Basis of Equine Nutrition, in WEVA Congress, 2023.
  5. Janssens, G. P. J. Horse Digestion and Bottlenecks in Formulating Horse Feeds. Proceedings of the First European Nutrition & Health Congress. 2002.
  6. Reed, S. M. et al. Equine internal medicine, 3rd ed. St. Louis, Mo: Saunders Elsevier, 2010.
  7. Krunkosky, T. M. et al. Gross and Microscopic Anatomy of the Equine Gastrointestinal Tract, in The Equine Acute Abdomen, A. T. Blikslager, N. A. White, J. N. Moore, and T. S. Mair, Eds., 1st ed. Wiley, 2017, pp. 1–18. doi: 10.1002/9781119063254.ch1.
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