Duodenal Ulcers in Horses: Causes, Signs, and Complications
- Duodenal ulcers affect the first part of the small intestine and are considered part of equine gastric ulcer syndrome (EGUS).
- Signs are often vague and can include poor appetite, mild recurrent colic, weight loss, attitude changes, poor performance, and in foals, drooling, teeth grinding, diarrhea, or poor nursing.
- Complications can be serious, including duodenal stricture, delayed stomach emptying, worsening stomach and esophageal ulcers, and rarely perforation.
- Diagnosis usually involves your vet combining history, exam findings, and gastroscopy; some horses also need bloodwork, abdominal ultrasound, or referral care.
- Treatment often includes acid suppression with omeprazole, management changes, and sometimes mucosal protectants such as sucralfate, based on your vet's plan.
What Is Duodenal Ulcers in Horses?
Duodenal ulcers are sores or erosions in the lining of the proximal duodenum, the first section of the small intestine just beyond the stomach. In horses, these lesions are generally grouped under equine gastric ulcer syndrome (EGUS) because ulcer disease can involve the lower esophagus, stomach, and the entrance to the duodenum.
These ulcers matter because the duodenum sits at a critical transition point in digestion. When this area becomes inflamed or ulcerated, a horse may develop vague digestive signs at first, then more significant problems if healing does not occur. In some cases, scarring can narrow the outflow from the stomach into the intestine, which can make other ulcers worse by slowing gastric emptying.
Adult horses and foals can both be affected, but the pattern may look different by age. Foals are at higher risk for severe peptic ulcer complications early in life, while adult horses more often show subtle signs such as poor appetite, low-grade colic, or reduced performance. Because the signs overlap with many other equine conditions, your vet usually needs to rule out several possibilities before deciding on a treatment plan.
Symptoms of Duodenal Ulcers in Horses
- Poor appetite or slower eating
- Mild, recurrent colic or abdominal discomfort
- Weight loss or poor body condition
- Attitude or behavior changes, including irritability with work or grooming
- Poor performance or reluctance to train
- Teeth grinding in foals
- Poor nursing in foals
- Excessive drooling in foals
- Diarrhea in foals
- Severe colic, reflux, or signs of gastric outflow obstruction
Many horses with ulcer disease show nonspecific signs, so the pattern matters as much as any one symptom. A horse that becomes picky with feed, loses condition, acts uncomfortable after exercise, or has repeat mild colic episodes deserves a conversation with your vet.
See your vet immediately if your horse has severe pain, repeated colic, marked depression, poor nursing in a foal, heavy drooling, or signs that feed is not moving out of the stomach normally. Those signs can point to complications such as delayed gastric emptying, stricture, or more extensive ulcer disease.
What Causes Duodenal Ulcers in Horses?
Duodenal ulcers in horses are thought to be peptic acid-related lesions, meaning stomach acid and digestive contents play a role in damaging tissue near the stomach outlet. In horses, ulcer disease is strongly linked with risk factors such as intense athletic work, high-concentrate diets, intermittent feeding, stall confinement, travel, social stress, and concurrent illness. Horses produce stomach acid continuously, so long gaps without forage can leave the upper digestive tract less protected.
Diet and management can add to that risk. Grain-heavy feeding and lower roughage intake are associated with ulcer development, while more continuous forage access helps buffer acid and increase saliva production. Some horses also worsen during periods of training, transport, or other stressors that change normal eating patterns.
In some cases, duodenitis or enteritis may contribute, and excessive or inappropriate use of NSAIDs can also injure the gastrointestinal lining. That said, ulcers are not caused by one single factor in every horse. Your vet will usually look at the whole picture, including age, workload, feeding routine, medication history, and whether there may be another intestinal or colic-related problem happening at the same time.
How Is Duodenal Ulcers in Horses Diagnosed?
Diagnosis starts with a careful history and physical exam, but symptoms alone are not enough to confirm duodenal ulcers. Many horses with EGUS have vague signs, and some horses with ulcers show very little outwardly. Your vet will ask about appetite, training intensity, turnout, travel, feed schedule, medications, body condition, and any episodes of colic or poor performance.
The most useful test for ulcer disease is gastroscopy, where your vet uses a long endoscope to examine the esophagus, stomach, pyloric region, and proximal duodenum. This is the best way to directly identify visible ulceration and assess severity. In practice, some horses are treated based on strong suspicion, but scoping is especially helpful when signs are persistent, severe, or not responding as expected.
Depending on the case, your vet may also recommend bloodwork, abdominal ultrasound, fecal testing, or referral evaluation to look for dehydration, inflammation, protein loss, other causes of colic, or complications such as delayed gastric emptying. If a horse has severe pain, reflux, or signs of obstruction, more urgent hospital-based workup may be needed.
Treatment Options for Duodenal Ulcers in Horses
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call and physical exam
- Empiric treatment plan from your vet when ulcer disease is strongly suspected
- FDA-approved omeprazole course when feasible, often without immediate gastroscopy
- Diet and management changes such as more continuous forage access, less grain, more turnout if appropriate, and reduced training intensity
- Targeted short-term follow-up to monitor appetite, comfort, manure, and body condition
Recommended Standard Treatment
- Exam plus gastroscopy to confirm ulcer location and severity
- Omeprazole treatment course, commonly about 28 days, with dosing tailored by your vet
- Possible addition of sucralfate for painful or more complicated upper GI ulcer disease
- Nutrition and management plan focused on frequent forage intake, stress reduction, and exercise modification
- Recheck exam and, in some horses, repeat gastroscopy to document healing
Advanced / Critical Care
- Referral hospital evaluation for severe pain, reflux, suspected obstruction, or foal complications
- Repeat or advanced endoscopy, bloodwork, ultrasound, and intensive monitoring
- IV fluids, pain control, gastric decompression or reflux management when indicated
- Combination medical therapy directed by your vet for severe ulceration or delayed gastric emptying
- Hospitalization and discussion of prognosis if stricture, perforation, or other major complications are suspected
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Duodenal Ulcers in Horses
Bring these questions to your vet appointment to get the most out of your visit.
- Based on my horse's signs, how likely are duodenal or pyloric ulcers compared with other causes of colic or poor performance?
- Would gastroscopy change the treatment plan in this case, or is a trial treatment reasonable first?
- Are there signs that suggest delayed gastric emptying, stricture, or another complication?
- What feeding changes do you recommend for my horse's workload, turnout situation, and body condition?
- Should we reduce training or hauling during treatment, and for how long?
- Is sucralfate appropriate along with omeprazole for this horse, and how should the medications be timed?
- What warning signs mean I should call right away or consider referral care?
- After treatment, what prevention plan makes the most sense for this horse's future ulcer risk?
How to Prevent Duodenal Ulcers in Horses
Prevention focuses on lowering the everyday factors that expose the upper digestive tract to acid and stress. Horses do best when they have frequent access to forage, fewer long fasting periods, and a feeding plan that does not rely heavily on large grain meals. Many horses at risk also benefit from more turnout, steadier routines, and less abrupt change in housing, herd dynamics, or travel schedule.
Management around exercise matters too. Intense work can increase acid exposure in the upper digestive tract, so your vet may suggest adjusting training intensity during high-risk periods. Some horses benefit from feeding forage, including some alfalfa when appropriate, before exercise to help buffer stomach contents. Any feed change should be made thoughtfully and with your vet's guidance.
Medication prevention is sometimes part of the plan, especially for horses with a history of ulcers during transport, competition, or other stressful events. Your vet may recommend a preventive omeprazole strategy in selected cases. It is also wise to review NSAID use, because dose, duration, and drug choice can affect ulcer risk. Prevention works best when it matches the individual horse's lifestyle rather than using a one-size-fits-all plan.