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                               Equine Ulcers – Literature Review

                                                By: Kim Maurin


Often when our horses are behaving poorly, we assume it is the weather. The reality is that many of our horses may be suffering from equine ulcers. 

Ulcers are sores that form on the lining of the stomach. It is suspected that 80 - 90% of performance horses, 70% of endurance horses, 63% of Dressage horses, 60% of show horses have ulcers, while only 50% for less used pleasure horses. Certain breeds are more susceptible to ulcers, such as Thoroughbred and Arabians 90%, warmbloods and sport horses 46-65%. The more active and traveled the horse, the more susceptible. Research shows that more strenuous exercise increases gastric acid production and reduces blood flow to the intestines, which increases the chance for ulcers. Additionally, during exercise, the stomach's acid splashes around, exposing the stomach's upper portion to more acidic pH fluids to exacerbate irritation.









There are three types of equine ulcers: 

Squamous stomach ulcers (upper stomach, most common) 

Glandular stomach ulcers (lower section of the stomach)

Colonic (hindgut, or hindgut acidosis). 


Traditionally, horses eat at a constant rate throughout the daylight hours, and the glands in their lower stomach produce acid 24/7 (up to 9 liters/day!) along with bicarbonate and mucus. When a horse eats forage, they produce saliva, which along with high-roughage feed, acts as a natural acid buffer. Food enters the stomach from the top and is mixed with acids to ferment and breakdown further. The top of the stomach is where food is mixed and does not have as much protection from the acid; this is where most gastric ulcers occur. 


Colonic Ulcers are when the acidic fluids are not moderated earlier in the gastric pathway and create high acid in the colon. Due to the colon's location, along the underside of the belly to the flank area, you often see girthiness and flank tenderness. On the right side



  • Gastric ulcer symptoms may be non-existent or subtle!

  • Changes in temperament, irritability

  • Preferring hay, avoiding grain

  • Tooth Grinding 

  • Loss of appetite

  • Difficulty maintaining weight or weight loss even if eating

  • Changes in hair coat

  • Poor behavior or attitude changes

  • Altered performance

  • Resistance to work

  • "Behavior issues"

  • Laying down more frequently or mild colic 

  • recurrent colic (almost always an ulcer).

  • Stretching often to urinate

  • Inadequate energy

  • Chronic diarrhea

Colonic Ulcers:

  • Resistance to grooming blanketing

  • cribbing

  • weaving

  • wood chewing

  • Flank sensitivity (Ceacum, part of the large colon only on the right side) 

  • Difficulty bending, collecting, extending

  • Low-Grade Colic

  • Girthiness (Right Dorsal Colon) and diarrhea are symptomatic of hindgut ulcers or acidosis.


Risk Factors:

  • Feeding less than 3 times/day

  • Feeding grain with high soluble carbohydrates and comprise a large amount of their diet.

  • Intense exercise

  • Trailering more than 5 miles

  • Bute/Banamine or NSAIDs (Nonsteroidal, anti-inflammatory drugs) impairs the mucosal blood flow and compromises the stomach's mucus-bicarbonate barrier. 

  • A high-grain diet, especially with high starch, tends to incite hindgut acidosis

  • Intermittent feeding

  • Stress

  • Management changes

  • Stall confinement

  • Particular breeds are susceptible



Gastric Ulcers - 

  • The only way to get a definitive diagnosis is by a veterinarian performing a gastric endoscopy (A three-meter long tube with a small camera attached). 

Colonic Ulcers - 

  • Difficult diagnosis 

  • Use of an Ultrasound (no one in the grand valley does this procedure, according to Dr. Carrica.)

General notes:

  • While palpitation can help identify areas of sensitivity, help locate possible areas of ulcers, it has not been proven as a reliable way to diagnose gastric ulcers. There can be many reasons for areas of discomfort. 

  • When ulcers are suspected, but endoscopy and ultrasound are not an option, many veterinarians will support Omeprazole treatment. 



• Omeprazole 

works to reduce the production of stomach acid

  • Paste $10/granules - Abler $5.80/day (Abler is a compounding pharmacy out of the country)

  • Primarily for Squamous ulcers (78% effective)

  • It takes 3 days to begin to work. 

  • Only 25% effective for Glandular. 

  • 15-30% of Squamous ulcers worsen despite treatment

  • 75% of Glandular ulcers worsen despite treatment

  • 28-day continuous dosage 

  • For the most effective results of medication, Omeprazole should be fed after an overnight fast. 

  • Timing of feed = withhold feed overnight, administer Omeprazole, 60 - 90 minutes of roughage, and then grain/supplemental feeding.

  • Once Omeprazole treatment is complete, Ad lidem feed is recommended.

  • Due to intestinal damage, DO NOT administer Bute with Omeprazole.

  • Beware of gastric rebound after completing a 28-day dosage. Once a horse has been treated and healed with Omeprazole for squamous ulcers, there is often a recurrence of ulcers. This is due to a phenomenon known as Rebound Acid Hypersecretion (RAHS). The body actually increases acid secretions after omeprazole treatment. The increase in acid can cause heartburn, acid regurgitation, and dyspepsia, leading to the formation of new ulcers.

  • Typically, the horse will resume treatment with Omeprazole once again, restarting the cycle. Consider an Equisure/RiteTrac/Ugard pH balancer feed supplement and pro/prebiotics.


A short term dosage of 30 - 60 days is less likely to be problematic for protein, calcium, and mineral absorption.

  • As of 2017, there is no research found in this review that has identified an Omeprazole overdose or concerns regarding risks associated with Protein Pump Inhibitors such as Omeprazole.  

  • It does impact calcium absorption. Limestone variant of calcium was reduced by 20% and KER's BMC by 15%.(small sample size)

  • Omeprazole draws calcium from the skeleton to maintain blood calcium to support muscle and nervous system function. (small sample size)

  • Some studies have also shown magnesium uptake.

  • study on Omeprazole published in the Journal of Equine Veterinary Science concluded: "Oral administration of Omeprazole in healthy equines interfered with the metabolism of digestive biomarkers of lipid, mineral and protein metabolism, although the animals were treated for a maximum of 11 days. Horses treated with a proton-pump inhibitor need to be evaluated regularly to avoid significant modification in their metabolic parameters." 



• Omeprazole injection (BET Pharmacy - a compounding pharmacy)

  • 1 shot/week for 2(CSU Study) -4 weeks ~$156.25/shot

  •  100% healing of ESGD over 3 weeks (24 horses, 2017)

  • 75% healing of EGGD over 2 weeks with a minimum of 4 weeks total treatment. (22 horses, 2017)

  • Same dietary requirements for efficacy

  • Injection sites should be administered in different areas to reduce injection site reactions.


• Misoprostol  

  • $50 - $80/day 

  • Is superior to Omeprazole/Sucralfate combination. 

  •  Misoprostol is given in conjunction with Omeprazole if no improvement after 30 days. 

  • To be used instead of Sucralfate


• Sucralfate 

Sucralfate is used to treat gastric ulcers and ulcers of the right dorsal colon in adult horses. It provides a protective coating to the horse's hindgut, allowing existing ulcers to heal. Sucralfate appears to provide significant pain relief in horses that show abdominal pain due to ulcers.

  • Protectant in combination with Omeprazole ($4.49/dose x 21 days or can be purchased with Omeprazole for $407 for a 30-day treatment program)

  • Should be administered 60 - 90 minutes after Omeprazole


• Omeprazole & Sucralfate (or Pectin-lecithin) in combination can provide more effective treatment for Glandular Ulcers


• Antibiotics may be necessary for Glandular Ulcers.


• Foods high in Amino Acids L-glutamine and L-threonine MIGHT aid in therapy as they help repair and nourish the cells lining in the stomach and intestines.


• Do not use antimicrobials as it is unclear at this time as to how they affect the gastrointestinal tract's biome.



  • Compounding pharmacies are frowned upon by Veterinarians because of non-FDA approved products. The FDA wrote to ABLER in 2014 that their ABprozole product had 11% more Omeprazole in the package than was listed on the bag. 

  • BET pharmacy was in a class-action lawsuit against the FDA in 2004 involving illegal inspections of their facilities and other unlawful activities concerning other compounding pharmacies. Currently, the FDA has Omeprazole under review. BET Pharmacy is no longer on the FDA watch list.



• On-demand forage or pasture - more saliva production, forage traps the acid in the lower portion of the stomach, protecting the stomach's upper regions.

• In lieu of pasture, hay nets with smaller holes. Horses "graze" all day.

• Decrease the stress of training. 

• Grain that is high-fat, high-fiber content - rice bran oils provide lipids that are water-soluble fats that help transport nutrients into the bloodstream and support healthy gut lining. 

• Alfalfa has a high calcium content that might provide an effect similar to antacids.

• Don't exercise on an empty stomach

• Prebiotics & probiotics

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