Does Omeprazole Reduce Cribbing in Horses?

Does Omeprazole Reduce Cribbing in Horses?

Researchers have linked gastric issues, such as colic or ulcers, and cribbing in horses, but they’ve never confirmed if one causes the other. So, a student at Randolph College, in Lynchburg, Virginia, sought to determine if treating gastric ulcers as the cause could reduce the notoriously difficult-to-curb behavior in cribbers.

Reilly Wren presented her study findings at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina.

One theory as to why cribbing sometimes occurs simultaneously with gastric ulcers, said Wren, is that it’s a relief mechanism for stomach discomfort. Cribbing increases saliva production, which helps buffer the stomach acid that causes painful gastric ulcers. When horses crib, they also produce β-endorphin, an opioid that not only gives them an endorphin “high” but also can provide pain relief, Wren explained.

So, in her study, she treated 15 known cribbers with either a control paste or a standard dose (1 mg/kg/day) of omeprazole (GastroGard, the only FDA-approved treatment for gastric ulcers) for 28 days. Her team did not scope the horses to confirm whether they had gastric ulcers, because their focus was on behavior changes, not ulcer resolution.

Before and after the treatment period, Wren noted each horse’s number of crib-bites and time spent cribbing. She also noted body condition score and collected blood and saliva samples to measure β-endorphin concentrations and saliva pH levels.

Wren did not find any significant behavioral or physiological changes in either the treatment or control group horses. Some owners did report improved overall behavior and a reduction in the frequency with which their horses performed other stereotypies.

As a result, said Wren, owners should not rely on this dose of omeprazole to treat cribbing.


Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

Dominance in Human-Horse Relationships

Our equine behavior expert examines if dominance has a role in human-horse interactions, especially during training.

Dominance in Human-Horse Relationships

People desire safe encounters, training success, and satisfying relationships with horses. The concept of dominance offers an appealing strategy for achieving these goals. According to dominance theory, unwanted behaviors such as bucking and biting are direct challenges to the person’s dominance status and can be resolved if the person gains “alpha” status. The principle is simple and popular, but scientists have recently expressed concerns about the use and misuse of dominance theory in equine training and handling.¹³ In this commentary, I summarize and expand on the some of these concerns.

Are Humans Included in the Equine Social Hierarchy?

One definition of dominance refers to an individual’s social status. Dominance rank is the animal’s position in the group, determined by its ability to compete for access to valued resources such as food. Dominance hierarchy refers to the relative positions of all members of the social group, and “alpha” designates the individual with the highest dominance rank. Most contests over resources occur between two individuals, and the largest, strongest, youngest, most experienced, most highly motivated, or temperamentally feisty competitor typically has the advantage. Dominance rank and hierarchy are useful constructs to scientists, but from a horse’s perspective what’s important—and remembered—are past interactions with other horses, which helps resolve future conflicts without fighting, reducing the risk of injury.

This definition is the foundation of the concept of dominance in human-horse interactions: To earn the horse’s respect, the human must hold the high ranking “alpha” position—never mind the horse’s advantage in size, strength, and speed. One question is whether the equine dominance hierarchy even applies to human-horse relationships. Researchers Elke Hartmann, PhD; Janne Winther Christensen, PhD; and Paul J. McGreevy, BVSc, PhD, MRCVS, MACVS (Animal Welfare), Cert CABC, Grad Cert Higher Ed, report that; “there is no evidence that horses perceive humans as part of their social system.”¹

Dominance is not a Substitute for Learning Principles

“Get after him!” “Don’t let him get away with that.” “Be the boss!” These familiar bits of advice are examples of a dominance approach to training. They assume that the horse’s unwelcome behavior directly challenges the human’s superior social status.¹ A serious concern is that more plausible explanations for the unwanted behavior—such as fear or anxiety, inadequate training, confusion, or medical issues—are often overlooked. For example, in one case, a filly would not move forward on the longe line. The owner believed that the horse did not respect her as a leader and attempted to resolve the issue by “getting after” the horse. A veterinary exam revealed that the filly actually suffered from a painful stifle defect requiring surgical repair.

Insufficient training is a common cause of unwelcome behavior. The proper use of learning principles can improve training success and prevent unwanted behavior. Horses learn more readily when they are attentive and calm, so training should reduce fear, not trigger or intensify it.² People who adopt dominance as a guiding principle for horse training and management are more likely to use harsh, punitive methods,¹,² and could become increasingly frustrated and angry if their efforts to prevent or correct the behavior are ineffective. Dominance is not a satisfactory substitute for a working knowledge of science-based learning principles.

Interpersonal Warmth Invites Trust

In psychology, “dominant-submissive” is one axis of the “interpersonal circle.”4 This model also includes a second “warm-cold” axis, and an individual’s relational style is a combination of dominance (low to high) and warmth (low to high). Examples of dominant traits are power, control, competitiveness, self-confidence, and a focus on one’s own needs; examples of warm traits are friendliness, love, compassion, trust, and a focus on the needs of others.

In any relationship, a person’s way of interacting pulls predictable responses from the other individual. These responses are reciprocal on the dominant-submissive axis (dominance evokes submission, and submission evokes dominance), and complementary on the warm-cold axis (warm invites warm, and cold invites cold).

People with a “warm-dominant” relational style are confident, encouraging, and friendly, and they inspire confidence and trust in others. Interpersonal warmth is an important predictor of relationship quality and satisfaction. People with a “cold-dominant” relational style are controlling and competitive, and have trouble expressing most emotions except frustration and anger. People who adopt a cold-dominant style bring out submissive, fearful, avoidant, withdrawn, or oppositional responses in others; it has been called the “dark side of personality and leadership.” In human relationships, conflict associated with a cold-dominant interpersonal style is resistant to change.

It is unknown if the interpersonal circle operates in animal societies, but it might describe how people engage with animals. Going beyond the concept of dominance, this model predicts that a person who is warm, nurturing, and focuses on the horse’s needs will have greater training success. Confident, supportive people also invite trust and curiosity and provide a secure base for the horse to take risks, which promotes both learning and a strong human-horse relationship.


¹​Hartmann, E., Christensen, J.W, & McGreevy, P.D. Dominance and leadership: useful concepts in human–horse interactions? Journal of Equine Veterinary Science 52 (2017) 1–9.

²International Society for Equitation Science. Position statement on the use/misuse of leadership and dominance concepts in horse training. (2017)


4Wiggins, J.S. An informal history or the interpersonal circumplex tradition. Journal of Personality Assessment 66 (1996) 217-233.


Robin Foster, PhD, CAAB, IAABC-Certified Horse Behavior Consultant, is a research professor at the University of Puget Sound in Seattle, Washington, and an affiliate professor at the University of Washington. She holds a doctorate in animal behavior and has taught courses in animal learning and behavior for more than 20 years. Her research looks at temperament, stress, and burn-out as they relate to the selection, retention, and welfare of therapy horses. She also provides private behavior consultations and training services in the Seattle area.

Transport and Exercise’s Effects on Horses’ Microflora

Stress not only leads to stereotypical behaviors and high cortisol (stress hormone) levels but also disrupts the horse’s gastrointestinal (GI) system and microbiome.

Transport and Exercise’s Effects on Horses’ Microflora
Stress triggers clear behavioral and physiological responses in horses. Stress not only leads to the development of stereotypical behaviors and high cortisol (the stress hormone) levels but also disrupts the horse’s gastrointestinal (GI) system, especially the microflora that reside there.Because it is impossible to eliminate all stress in our horses’ lives, Kyla Szemplinski, a 2018 master’s degree graduate of Tarleton State University, in Stephenville, Texas, sought to find out how common stressors—transport and exercise, which we can theoretically control-affect the equine microbiome. She shared her findings at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina. Her thesis committee included Trinette Jones, PhD; Kimberly Guay, PhD; Brandon Smith, PhD; and Jeffrey Brady, PhD.

In her work, Szemplinski studied four drylot-kept adult Quarter Horses consuming free-choice grass (coastal Bermuda grass) hay and a concentrate grain designed for horses of all ages and activity levels. During the transport phase, she hauled each horse in a 16-foot aluminum trailer for 15 minutes, three hours, and six hours, with seven days between each trip. In the following exercise phase, she free-longed three of the four horses at low, medium, and high intensity, with seven days between each exercise session.

Szemplinski collected fecal samples from each horse two hours after its morning meal and 48 hours post-transport or -exercise. She used these samples to assess the horses’ microflora DNA and found that:

  • Exercise did not affect microflora diversity.
  • Bacteroidetes (bacteria that help break down cellulose and pectins in plant cell walls) populations increased post-transport.
  • Firmicutes (which help produce amino acids) decreased post-transport.

The latter two changes were most significant when horses were trailered for at least six hours.

“Further research with longer transport time (more than six hours) and more intense exercise stress are needed to further explore how these two common stressors affect the microflora populations,” Szemplinski said.

In the meantime, owners can be cognizant of transport’s effect and exercise’s potential effect on their horses’ GI systems. Watch for signs of loose stool or gastrointestinal upset, which could indicate microflora disruption and might warrant a call to your veterinarian.


Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

Picky Eater? Add Anise Flavoring to Your Horse’s Feed

A researcher tested common oil-based palatants to find out which horses liked best. Here are her results.

Picky Eater? Add Anise Flavoring to Your Horse's Feed

Manufacturers often add palatants such as peppermint to feeds and medications to make them more appealing to horses. But which flavors do horses truly like?

Jesse Francis, a graduate student at Southern Illinois University, in Carbondale, tested common oil-based palatants to find out. She shared her results at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina.

In her study Francis presented 10 mature stock-type horses with pelleted feed top-dressed with six flavors—anise, apple, banana, orange, peppermint, and spearmint—plus a corn oil control in paired comparison preference tests. They were allowed 15 seconds to sniff the palatants, then three minutes of access to consume the one(s) they preferred.

“The purpose of the sniffing period was to allow the horses to make informed decisions about which diets they wanted to consume,” said Francis.

Though not statistically different, she found that horses selected anise most frequently (65% of the time) and banana and orange least (30% and 35% of the time, respectively). Horses even preferred the plain corn oil control over the orange, she said.

Francis then compared the three most popular palatants—anise, apple, and peppermint—against each other in a second study phase. Using the same design, she noted that anise was again the most consumed flavor, with horses eating more anise-flavored feed than peppermint or apple. Interestingly, said Francis, the horses did not sniff the anise as frequently as they did the apple flavor.

“Oil-based palatants do affect horses’ concentrate preferences,” Francis concluded, noting that her findings are consistent with previous research. She plans to investigate the impact of scent on flavor and feed preference in horses in future studies.

So, the next time your picky eater turns his nose up at his dinner, consider adding anise flavoring to it, and steer clear of citrus.

Horse Vitamins: What’s an IU?

International units are used to quantify similar biologically active substances such as vitamins and hormones. Our equine nutritionist explains.

Horse Vitamins: What's an IU?

QUESTION. I notice on feed and supplement labels that vitamins are typically quantified in “IUs.” What is an IU, and why is it used for vitamins?

ANSWER. IU stands for international units and is a metric system of measure. An IU is used to quantify similar biologically active substances such as vitamins and hormones. They allow for comparison of different preparations of substances with the same biological effect. The exact measurement of one IU varies depending on the compound in question, meaning an IU of vitamin A is not the same as an IU of vitamin D. Essentially, an international agreement exists as to how much of a given compound constitutes an IU.

For example, vitamin E comes in several forms, including alpha tocopherol and dl-alpha tocopherol. These two forms of vitamin E have similar biological activity, but slightly different amounts are needed to have the same biological effect. One IU of vitamin E is the biological equivalent of 0.67 milligrams of alpha tocopherol or 0.9 milligrams of dl-alpha tocopherol. This means that to get the same biological activity you will need more vitamin E if you are using the dl-alpha tocopherol compared to the alpha tocopherol form. Note that this is why we say natural vitamin E (alpha tocopherol) is more “bioavailable” than synthetic vitamin E (dl-alpha tocopherol).

An IU of vitamin A has the biological equivalent to 0.3 micrograms (1/1000th of a milligram) of retinol or 0.6 micrograms of beta-carotene. Vitamin D from cholecalciferol and ergocalciferol has the same biological activity, so in each case 0.025 micrograms of either is 1 IU.

If you want to know how many milligrams of a certain form of a vitamin a feed contains, look at the feed tag’s ingredient list and guaranteed analysis. For example, when looking at vitamin E, if the ingredient list shows dl-alpha tocopherol and guarantees 250 IU of vitamin E, you would multiply the number of IU by 0.9. So in the case of 250 IU, this would be 225 milligrams of dl-alpha tocopherol.

Conversely if a product gives you the amount of vitamin E in milligrams and is using dl-alpha tocopherol and you want to compare it to other products that state IUs, you would multiply the number of milligrams by 1.1. Therefore, a product with 50 milligrams of vitamin E per serving from dl-alpha tocopherol would provide 55 IU. Now you can compare this to other products that state IU regardless of source, because if they have the same number of IUs they should have the same biological activity.

On first glance the IU system can seem arbitrary, but it allows for useful comparisons across similar compounds.


Clair Thunes, PhD, is an equine nutritionist who owns Summit Equine Nutrition, based in Gilbert, Arizona. She works as a consultant with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses and provides services to select companies. As a nutritionist she works with all equids, from WEG competitors to Miniature donkeys and everything in between. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the U.K. Pony Club. Today, she serves as the district commissioner for the Salt River Pony Club.

What’s the Difference Between Gastrogard and Ulcergard?

One is prescribed by your veterinarian, the other is available over-the-counter. Find out more in our Q&A.

What's the Difference Between Gastrogard and Ulcergard?
QUESTION : What’s the difference between Gastrogard (omeprazole) and Ulcegard (omeprazole), and why do I have to get one from my veterinarian while the other is available at my local feed store?

ANSWER: That’s a great question—I know it can be a confusing issue for horse owners.

While both products contain the same specially formulated omeprazole, are proven and FDA-approved, and are manufactured and distributed by the same company, there is a difference between the two.

Gastrogard is used to treat existing equine stomach ulcers. To make a diagnosis, your veterinarian may examine your horse by running an endoscopic camera through its nose, down the esophagus, and into the stomach. If an endoscope is not available, your veterinarian might make a presumptive diagnosis based upon the horse’s history and clinical signs.

If stomach ulcers are diagnosed, Gastrogard is the only proven and FDA-approved product for treating them. When used as directed, and accurately dosed for the weight of your horse, the ulcers should be improved and possibly healed in 28 days. This will depend on the severity or grade of stomach ulcers at the time of diagnosis.

Ulcergard, on the other hand, is used to help prevent your horse from developing stomach ulcers. A horse is prone to developing stomach ulcers during times of stress which include, but are not limited to, training, competition, trailering, confinement (stalling a horse or keeping it in a small paddock), social regrouping, or weaning. When used as directed (a quarter of a tube per day), during these times of potential stress, Ulcergard helps prevent the formation of equine stomach ulcers in horses weighing 600 to 1,200 pounds. Talk with your veterinarian if you horse weighs more than 1,200 pounds to determine the appropriate preventive dose.

Because it is a preventive medication and not being used for treatment, Ulcergard does not require a prescription and thus can either be sold by your veterinarian or purchased in retail outlets. It is the only proven and FDA-approved product for preventing equine stomach ulcers.

It’s important to remember to check the label when putting any product in your horse’s body. Look for the New Animal Drug Application (NADA) number and the statement “Approved by the FDA” on the product’s packaging. This will assure the product has been thoroughly tested for both safety and effectiveness.

Weed Management Plans for Horse Pastures

Fall is a good time to evaluate the quality of your horse pastures, because it is easy to see which weeds were most prevalent and uncontrolled during the summer and are now large and seed-producing.

Weed Management Plans for Horse Pastures
Fall is a good time to evaluate the quality of your horse pastures each year, because it is easy to see which weeds were most prevalent and uncontrolled during the summer and are now large and seed-producing. It is also a good time to develop a weed management plan for pastures in the coming year. When creating an effective weed management plan, consider: the pasture’s purpose, weed species and abundance, which weeds should be controlled and the method of weed control, and sources of information.

Purpose of the pasture.

If pasture is a significant portion of your horses’ diet, you’ll want a high-quality, nearly weed-free forage. Conversely, a “pasture” maintained as a drylot for feeding horses will contain many weeds, but there is little reason to control these weeds since there are few, if any, desirable forages in the drylot. Kentucky horse pastures usually are maintained between these two extremes. Property owners often ask why these weeds are in their pastures, followed by what they should do about them. Forages grown with adequate fertility and not overgrazed will limit weed occurrence but not prevent all weeds from growing.

Weed species, abundance, and distribution.

Plants that we call weeds grow in ecological niches–environments that allow for germination, vegetative growth, and maturation. Horse pastures provide several of these ecological niches that allow some weeds to thrive. Kentucky is located in the temperate transition zone that in which both warm-season and cool-season plants grow.

Warm-season weeds germinate in spring or early summer, grow, and produce seeds before frost.  Cool-season weeds germinate and produce some growth in the fall and seeds the following spring or summer.

When pastures house many weed species, horse pasture managers face the challenge of determining which weeds, if any, they should control. The most abundant weeds in horse pastures are usually annual species that produce thousands of seeds. Spiny pigweed, also known as spiny amaranth, produces more than 100,000 seeds per plant. This weed is widespread and occurs most often in compacted areas along fences and around feeding and watering areas of pastures. Spiny pigweed is also a good example of the “patchiness” of weeds; they often grow only in certain portions of the pasture where their ecological niche occurs.

Which weeds to control and method and time of weed control.

Generally, you should remove poisonous weeds and weeds that inhibit grazing from a pasture.

Poison hemlock occurs widely across Kentucky and is toxic to horses and other animals. Although horses rarely eat it, you should remove it from the pasture.

Musk thistle and bull thistle are found throughout Kentucky and inhibit grazing. Canada thistle occurs less frequently but also inhibits grazing and is more difficult to control.

Large crabgrass and yellow foxtail are warm-season grasses of summer. Horses graze the large crabgrass but not yellow foxtail.

Buckhorn plantain is a cool-season plant that horses consume when pasture grass is limited.  Many small, tender “weeds” are nutritious and readily consumed when small but rarely consumed as large plants.

Methods of removing horse pasture weeds are limited to hand removal, mowing, and herbicides, and each has its advantages and disadvantages.

Hand-weeding can be very effective and is particularly useful for removing poisonous plants, such as poison hemlock, from a pasture. You should not only control poisonous plants but all remove them from the pasture to prevent animals from consuming them.

The downside of hand-weeding is that the process is slow and inefficient for large areas.  Mowing is rarely effective at killing weeds in pastures—mowing low enough to kill the weeds (2 inches or less) removes valuable forage. Mowing heights of about 6 inches will keep some large weeds from producing seeds but does not control smaller weeds.

Herbicides are efficient and provide excellent control, but in transition zone areas such as Kentucky, one herbicide will not control all the weeds with one treatment.

There are optimum times to control weeds with herbicides. The following months are the preferred time for herbicide treatment for several weedy species in Kentucky:

  • October-November: Common chickweed, henbit, purple deadnettle, dandelion, buckhorn plantain, musk thistle, bull thistle, Canada thistle, poison hemlock
  • February-March: Buttercups, curly dock, broadleaf dock, chicory
  • May-July: Spiny pigweed, white clover, hemp dogbane, goldenrod, cocklebur, perilla mint, common ragweed, jimsonweed

Sources of information.

Consult your local Cooperative Extension Service agricultural agent for specific information on herbicides in your area. Remember, not all herbicides are registered for use in all states and countries, so read the label carefully, and follow all directions. Many Cooperative Extension Services have publications regarding weed control in pastures, including:

William W. Witt, PhD, emeritus professor and weed scientist with the University of Kentucky’s Department of Plant and Soil Sciences, provided this information. Email:

Blue-Green Algae: Dangerous to Pets and Livestock

lue-green algae can produce toxins that affect the nervous system and liver. Exposed animals can die quickly, or they can develop liver failure over several days. Get tips to protect your horse.

Blue-Green Algae: Dangerous to Pets and Livestock
Blue-green algae, also called cyanobacteria, are microscopic organisms normally present in aquatic ecosystems, including lakes and ponds. Scientists have identified thousands of species of blue-green algae; at least 80 are known to produce toxins that can cause illness and death in animals as well as humans.Heavy growth of these toxin-producing algae (“blooms”) can cause high concentrations of toxins in the water. In North America, Anabaena, Aphanizomenon, Oscillatoria, and Microcystis are the blue-green algae species most commonly associated with poisoning.

In Central Kentucky, blooms are most common in late summer and early fall, during hot, sunny weather. Contamination of water with excess nutrients, particularly nitrogen and phosphorus, further encourages algal growth. Common sources of excess nutrients include fertilizer runoff from fields, lawns, and gardens and direct manure and urine contamination from livestock.

Blooms can produce a blue-green sheen on the water surface, or they can be pea-green and thick, like spilled paint. Blooms can also be brown or white. They can form scums, slimes, or mats. It is impossible to tell if a bloom is toxic just by its appearance; consider all blooms potentially toxic.

Blue-green algae can produce neurotoxins (affecting the nervous system) or hepatotoxins (causing liver damage), and some species can produce both types. Neurotoxins can cause muscle tremors, seizures, excessive salivation, diarrhea, difficulty breathing, and death within hours or even minutes of exposure. Hepatotoxins cause vomiting, diarrhea, bloody or dark stool, and pale or jaundiced (yellow) mucus membranes. Animals can die quickly, or they can develop liver failure over several days.

There are no antidotes for blue-green algae toxins, so early decontamination and supportive care can mean the difference between life and death for an exposed animal. If your pet develops these or any other signs after recent exposure to water—even water with no obvious algal blooms–seek immediate veterinary care. Toxins can persist in the water for more than a week after the bloom itself has collapsed.

To prevent blue-green algae poisoning in pets and livestock:

  • Provide plentiful clean, clear, fresh water for your animals. Keep water bowls, buckets, and troughs clean and well-maintained.
  • Never let your pets (or children) swim in, play in, or drink discolored, slimy, scummy, or otherwise suspicious water. Assume any bloom is toxic.
  • Pay attention to local health and water advisories and respect any water body closures. Water that appears clean can still contain high concentrations of toxins.
  • Fence off farm ponds, creeks, and other natural water sources to prevent livestock from contaminating them as well as drinking from them.
  • Fence off backyard ponds and other natural water sources to keep pets from accessing them.
  • Prevent fertilizer and/or manure from running off into water sources.
  • If your pet does access suspicious water, wash him thoroughly with clean, fresh water, and prevent him from licking his fur. Wash your own hands and arms after washing your pet, as exposure to blue-green algae can cause skin, eye, nose, and throat irritations in humans.
  • If animals become ill after exposure to a pond, lake, or other natural water source, seek immediate veterinary care – even if the water appeared clean, toxins can still be present. Tell your veterinarian if your animal might have been exposed to blue-green algae. This can help direct treatment, as many other illnesses can have similar signs.

Megan C. Romano, PhD, Veterinary Toxicology Resident, University of Kentucky Veterinary Diagnostic Laboratory, provided this information.

Marine-Derived Minerals Might Improve Equine Bone Density

One researcher saw interesting bone changes in racehorses in training who received a supplement containing marine-derived minerals.

Marine-Derived Minerals Might Improve Equine Bone Density
Studies have shown that marine-derived sources of minerals can improve bone strength and density in lab animals and humans. But what effect might they have on Thoroughbred racehorses, which depend on strong bones for long-term soundness?Joe Pagan, PhD, founder of Kentucky Equine Research (KER), in Versailles, recently conducted a study on the topic. He presented his results at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina.

Pagan included in his study 14 Thoroughbred racehorses in training over a 12-week period. Their diets during this time consisted of free-choice timothy hay, fortified feed, electrolytes, and free-choice salt—designed to meet or exceed the nutrient requirements of horses in heavy work. Seven horses in the treatment group also received a marine-derived complex with trace minerals and vitamins (the supplement Triacton), and seven received a placebo.

“We were interested in looking at bone changes such as density and mineral content,” during the study period, he said.

During Weeks 0, 4, and 12, Pagan took radiographs of each horse’s left front cannon bone to estimate bone density. He said he found no significant differences in bone or cortical (bone’s hard outer layer) width or medial or lateral density (inside or outside of the bone) between treatment groups but did, however, note an increase in dorsal and palmar (front and back of cannon, respectively) cortical bone density in the supplemented horses.

“We have to chalk some of these changes up to horses being in training (bone responds to the stress of exercise by laying down more bone cells),” said Pagan. “But since the supplemented horses increased bone density more than the unsupplemented horses, we might also be positively affecting density by adding these nutrients in addition to horses’ normal nutrient requirements.”


Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

Hard to Stomach: Equine Gastric Ulcer Syndrome

Learn to read the vast and varied signs of equine gastric ulcer syndrome.

Hard to Stomach: Equine Gastric Ulcer Syndrome

Learn to read the vast and varied signs of equine gastric ulcer syndrome

The gelding that kicks the stall wall and acts aggressively toward his neighbors at feeding time. The show horse that’s increasingly more reluctant to perform under saddle. The angsty mare that’s always swishing her tail and grinding her teeth. Many owners observe these quirks in their horses and chalk them up to behavioral issues. But is it truly bad behavior or is it a sign of discomfort? As you’re about to find out, equine gastric ulcer syndrome (EGUS) might be to blame.

Stomach Anatomy Basics

The horse’s stomach has two regions: a nonglandular (squamous mucosa) portion comprising the upper third, and a glandular lower portion. The squamous nonglandular region doesn’t feature the thick, protective mucus and bicarbonate (a pH buffer) layer that the glandular region does, leaving it vulnerable to ulceration from gastric acid. 

Frank Andrews, DVM, MS, Dipl. ACVIM, LAIM, LVMA, equine committee professor and director of the Equine Health Studies Program at Louisiana State University’s School of Veterinary Medicine, in Baton Rouge, likens ulcers in the squamous mucosa in horses to gastroesophageal reflux disease (GERD) in humans, in which gastric acid damages the esophageal lining. 

“When the horse has an empty stomach or acid in the stomach due to stress, that acid may splash onto the nonglandular mucosa, especially when exercising,” he says, explaining that the hydrochloric acid the cells in the glandular mucosa produce might damage it.

While the stomach’s glandular region enjoys protective mechanisms such as prostaglandins that maintain mucus and blood flow, it’s not immune to ulcer issues, says Andrews. “The glandular mucosa is less susceptible to acid damage, but it is susceptible to stress, dehydration, and dietary issues,” he says.

Those dietary issues include high-sugar diets, Andrews explains, such as large amounts of sweet feed, which, when fermented by the stomach’s natural bacterial flora (microbiota), create short-chain fatty acids that can eat away at the stomach lining. Other factors can also contribute to glandular ulcers, such as non-steroidal anti-inflammatory drug (NSAID) use, including Bute (phenylbutazone), Banamine (flunixin meglumine), and even Equioxx (firocoxib), which Andrews notes researchers have recently determined can have some deleterious effects on the glandular stomach. 

Ulcer Signs to Watch For: Nosing or kicking at the abdomen

Signs to Watch For

At the University of Pennsylvania School of Veterinary Medicine’s (Penn Vet) New Bolton Center, in Kennett Square, horses are sometimes video-monitored over a 24-hour period to assess behavioral patterns that might suggest physical discomfort, says Sue McDonnell, MS, PhD, CAAB, founding head Penn Vet’s Equine Behavior Program. She notes that when horses exhibit attitude or performance changes, they often have gastric ulcers as a primary or a secondary problem.

“In my experience, at least 60-70% of horses that have gastric ulcers show some sort of behavior suggesting discomfort around the time of feeding or whenever they have not had something to eat for a few hours,” she says. “The signs a horse might show are highly variable between individuals and might even be different within an individual over time.” These, say McDonnell and Andrews, might include:

  • Looking back at or nosing the abdomen behind the shoulder, on both sides of the body. The coat might be ruffled where the horse nuzzles repeatedly;
  • Acting anxious or restless in combination with clusters of behaviors suggesting physical discomfort (weight-­shifting, rotational headshaking, kicking up at the abdomen, tail-­swishing or -slapping, lip-licking, tongue extension, and chewing motion when not eating);
  • Food-aggressive behaviors around feeding time, such as rushing to the feed bucket, pawing, threatening neighbors, and kicking the wall;
  • Reluctance to perform;
  • General grumpiness with herdmates and/or caretakers;
  • Rough hair coat;
  • Weight loss and poor body condition;
  • Girthiness;
  • Mild colic episodes;
  • Intermittent eating patterns (leaving feed for a time and then returning);
  • Teeth-grinding;
  • Lack of energy;
  • Decreased water intake;
  • Stretching out as if needing to urinate;
  • Lying down more than normal; and
  • “Just not looking or acting right.”

“What we see are vague clinical signs, so we spend a lot of time talking with the owners, the trainers, and the people that handle the horse to see if they notice any of these things,” says Andrews.

McDonnell says that when comparing gastroscopy findings (those seen when the veterinarian views the horse’s stomach through an endoscope passed through his nostril and down the esophagus), some horses with minor ulceration might show dramatic behavioral changes, while horses with more extreme ulceration might exhibit only mild symptoms. “The message should be that individuals may have a varying response,” she says.


Arriving at a Diagnosis

“We know that if we are going to try to figure out the reason for a behavior change, we don’t want (the horse) to have ulcers on board at the time,” says ­McDonnell. “A wise first step is to have gastroscopy performed to establish from the beginning if the horse does or does not have gastric ulcers. For those with ulcers, the usual recommendation is to treat and then confirm healing with follow-up gastroscopy. If behavior problems remain, you can then work on figuring out what else might be bothering the horse.”

While the only definitive method of diagnosis is gastroscopy, says Andrews, owners and veterinarians can, in his opinion, consider treatment first. “We obviously like to have a diagnosis, but I don’t think it’s wrong for a practitioner to give a seven-day trial treatment with GastroGard (the trade name for omeprazole, used to treat stomach ulcers),” he says. To again draw an analogy to human medicine, Andrews says, “People experiencing dyspepsia (indigestion) don’t typically get scoped on the first visit; they might get a sample of Prilosec (omeprazole) or Nexium (esomeprazole) with the instructions to ‘Try these and call us back.’ ”

If the behavioral signs resolve with treatment, then you have your ulcer diagnosis, as omeprazole does not affect any other behavior-altering diseases, he says.

Andrews says recently introduced tests that measure blood in the manure to diagnose EGUS have not been fully validated yet in horses.

“The human card test, ‘guaiac test,’ was evaluated and found to be helpful when positive, but when negative, many of those horses had ulcers also,” he says. “The test was developed for people as a colon cancer screening test, but it’s less reliable in horses as a diagnostic test for stomach ulcers,” because blood in manure could come from anywhere in the GI tract.

Some horses with ulcers might have mild anemia, says Andrews, who suggests owners have blood drawn during horses’ annual checkups to establish a bloodwork baseline. “While levels may be within the normal range, if you follow the horse throughout the years, you may see the red blood cell count decrease, which could signal the horse is having an issue with ulcers.”

Treatment Plans

Omeprazole (again, GastroGard) and the lower-dose product (UlcerGard) are currently the only FDA-approved drugs for treating and preventing stomach ulcers in horses. While both products contain the same active ingredient, UlcerGard is designated for gastric ulcer prevention and GastroGard for treatment and prevention of recurrence. UlcerGard, says Andrews, delivers one quarter the dose of omeprazole that GastroGard paste does.

In addition, Andrews includes a supplement regimen. “Supplements like SmartGut Ultra (which contains sea buckthorn, pectin, lectin, glutamine, and aloe vera) do have some protective properties so, when we treat with GastroGard, I’ll simultaneously supplement with SmartGut Ultra to help maintain stomach health,” he says.

After the manufacturer’s recommended month of initial treatment, Andrews suggests tapering the GastroGard dose. “We’ll go from a typical 1,000-lb (horse) dose of 4 mg/kg to 1 mg/kg for two weeks before taking the horse off the medication,” he says. “GastroGard inhibits gastric acid secretion, but it leads to increased gastrin (a hormone) in the blood; that gastrin will stimulate parietal (stomach wall) cells after discontinuation of treatment, causing rebound hyperacidity.” Tapering the dose helps prevent this.

Good Horsekeeping

Certain management tactics can help ward off gastric ulcers and their accompanying negative behaviors.

“I don’t think horses should go more than about an hour without access to some sort of roughage, which appears to be quite protective against ulcers,” says McDonnell. “When horses are without hay, they begin to rummage around and may lick walls and chew on wood.”

Horses evolved as trickle feeders, she explains, meaning they are meant to graze or browse almost continuously, punctuated with short 30-minute rest breaks.

After treatment Andrews recommends owners try to mitigate ulcers by changing management strategies. “We recommend no more than 5 pounds (twice a day) of sweet feed,” he says. “Owners might feed more grain if it’s a low-sugar (low-starch) grain. Studies show adding corn oil (4 to 8 ounces, twice daily) to the diet helps increase mucous production and might increase blood flow by increasing protective prostaglandins (lipid compounds that behave like hormones) in the glandular portion of the stomach. In addition, corn oil supplementation will add energy to the horses’ diet and produce a shiny hair coat,” Andrews says.

He offers a few other general management strategies:

  • Take advantage of pasture turnout;
  • Minimize stress;
  • Get the horse out of the stall and into a social group he gets along with; and
  • If the horse is on phenylbutazone or flunixin meglumine, reduce the dose, if possible, or switch to firocoxib, which is a “COX-1 sparing,” or COX-2 selective drug; COX-1 is an enzyme that plays a role in protecting the stomach lining.
On the Road

On the Road

Traveling, competing, and life on the road present their own set of challenges. Andrews recommends taking a proactive approach to maintain stomach health in the face of travel stress. He suggests:

  • Bringing hay from home or having hay shipped in for a consistent diet;
  • Considering feeding alfalfa, which increases stomach pH and neutralizes stomach acid, offering buffering effects;
  • Encouraging water consumption by acclimating the horse to flavored water at home or offering one bucket of fresh water and one bucket with flavored gelatin or Gatorade added. Find a flavor the horse likes, so he will turn to the familiar taste of flavored water and drink more on the road, maintaining hydration and reducing stress;
  • Adding a product comparable to Morton’s Lite Salt (potassium/sodium chloride mixture) to the grain to stimulate the desire to drink; and
  • Administering preventive UlcerGard when shipping.

Andrews describes a new feed product, Purina Outlast, which he says the company tested on horses with heavy travel schedules. It features a proprietary calcified product touted for buffering stomach contents. While other buffering products do exist, they have not been tested as rigorously as this one, he says.

“Outlast supplement added to the grain prevented ulcers from becoming more severe compared to the horses fed the regular grain,” says Andrews. “This product might be helpful for horses in stressful situations and periods at risk for gastric ulcers, especially during travel.”

The Whole Horse

When addressing ulcer issues, McDonnell says the more natural environment the horse lives in, the less stress he’ll experience as a whole. “We often see horses return to the clinic with a relapse of ulcers. You do need to address the horse’s environment if you expect them to remain ulcer-free for long,” she says. “You have to look at the entire program, not just nutrition. Unfortunately, stressors of all types appear to contribute to ulcers, and ulcer discomfort itself is stressful, so there may be a downward spiral.”

While some horses are simply predisposed to ulcers, says Andrews, if you manage diet and stress, you can help minimize your horse’s possibility of getting them. And that makes for a happier horse and a happier you.


Freelance journalist Natalie DeFee Mendik is a multiple American Horse Publications editorial and graphics awards winner specializing in equestrian media. She holds an MA in English from Colorado State University and an International Federation of Journalists’ International press card, and is a member of the International Alliance of Equestrian Journalists. With over three decades of horse experience, Natalie’s main equine interests are dressage and vaulting. Having lived and ridden in England, Switzerland, and various parts of the United States, Natalie currently resides in Colorado with her husband and two girls.