Ulcers in Horses Explained: Signs, Prevention, and Care

Up to nine in ten racehorses in hard training have stomach ulcers, and so do between a third and six in ten sport and leisure horses. Those are the gastroscopy ranges collected in the European College of Equine Internal Medicine (ECEIM) consensus statement on Equine Gastric Ulcer Syndrome (Journal of Veterinary Internal Medicine 2015;29:1288-1299), and they make ulcers in horses one of the most common and most under-diagnosed conditions in UK and South African yards.

This guide explains Equine Gastric Ulcer Syndrome (EGUS), the two distinct ulcer types every owner needs to know, the symptoms to watch for under saddle and in the stable, current UK veterinary treatment costs, and the management changes that prevent recurrence.

What Are Ulcers in Horses

An equine gastric ulcer is an erosion in the lining of the horse’s stomach. The horse’s stomach is small (around 8 to 15 litres) and evolved for almost-constant trickle grazing. It produces stomach acid continuously, around 1.5 litres per hour, whether food is present or not. When the protective mucosal barrier breaks down, acid eats into the underlying tissue and creates the painful lesion known as a gastric ulcer.

The umbrella term used by UK and international vets is Equine Gastric Ulcer Syndrome, abbreviated EGUS. The 2015 ECEIM consensus statement – which is still the current consensus document, despite a widely repeated reference to a 2020 update that does not exist – divides EGUS into two distinct diseases that share a name but differ in cause, location and treatment. Treating them as one condition is the single most common mistake in equine veterinary practice.

The Two Types of Equine Gastric Ulcers

The horse’s stomach is divided into two regions by a clear ridge called the margo plicatus. The upper portion is the squamous (non-glandular) region; the lower portion is the glandular region. Ulcers in each region are a different disease.

ESGD: Equine Squamous Gastric Disease

ESGD occurs in the upper, unprotected portion of the stomach. Acid splashes upward into the squamous lining during exercise, fasting or stress, and burns through it. ESGD is the type most owners think of when they say “ulcers”. It is strongly linked to intense exercise, intermittent feeding and high-starch diets.

• Prevalence (ECEIM 2015): 37 per cent of untrained Thoroughbreds, rising to 80 to 100 per cent within 2 to 3 months of race training; 17 to 58 per cent of show and sport horses; 37 to 59 per cent of pleasure horses.
• Risk peaks within 2 to 3 weeks of a change in workload, transport or routine.
• Responds to omeprazole in around 70 to 80 per cent of cases. ECEIM reports healing rates of 70 to 77 per cent over a 28-day course, not the near-total resolution often quoted.

EGGD: Equine Glandular Gastric Disease

EGGD occurs in the lower glandular region, which is normally protected by mucus and bicarbonate. The cause is less well understood. Stress (psychological and physiological), NSAIDs, and breakdown of the mucosal barrier appear to drive it. EGGD is more common in warmbloods and is harder to treat than ESGD.

• Prevalence: around 50 to 60 per cent in sport horses, often co-occurring with ESGD.
• Linked to exercise frequency rather than intensity: exercising five or more days a week carried a 10.4 times higher risk of EGGD in Thoroughbred racehorses (Sykes et al., Journal of Veterinary Internal Medicine 2019;33:233-240). The threshold is five days, not six.
• Responds less well to omeprazole alone; often requires sucralfate, misoprostol, or a combination of agents over a longer course.

It is the ECEIM consensus, not BEVA, that sets this position: the committee considers gastroscopy “the only reliable antemortem method for definitively identifying gastric ulceration” and does not recommend starting treatment without it. Treating “ulcers” empirically with a 28-day course of omeprazole without scoping first wastes money on the horses that have EGGD and misses an opportunity to fix the management problem driving the disease.

What Causes Ulcers in Horses

Ulcers are a management disease. The horse’s anatomy assumes continuous slow grazing of fibrous forage. Modern stable life often delivers the opposite.

• Intermittent feeding. Stomach acid is produced 24/7. Without a fibrous mat soaking it up, acid splashes onto the squamous lining. Gaps of more than six hours between forage feeds significantly increased the risk of squamous ulceration in a study of 201 Danish horses (Luthersson et al., Equine Veterinary Journal 2009;41:625-630).
• High-starch concentrate feeds. Grain ferments rapidly in the stomach and produces volatile fatty acids that damage the squamous mucosa. The measured thresholds in that same study were more than 1 g of starch per kg bodyweight per meal, or more than 2 g per kg bodyweight per day. The per-meal limit is 1 g/kg, not 2 – the 2 g/kg figure is the whole day’s total, and feeding it in a single meal doubles the evidence-based per-meal load.
• Intense exercise. Galloping compresses the stomach, pushing acid upward against the squamous lining. ESGD risk rises with the volume of fast work.
• NSAIDs. Long-term use of phenylbutazone (bute) or flunixin reduces the protective prostaglandin layer in the glandular region. A documented driver of EGGD.
• Stress. Transport, weaning, isolation, change of yard, hospitalisation, and even prolonged box rest all raise cortisol and reduce mucosal blood flow.
• Limited turnout. Associated with higher ESGD risk in some studies and not others. ECEIM calls the evidence on turnout “conflicting”, and no study supports a specific hours-per-day threshold.
• Lack of water. Dehydration concentrates stomach acid. Horses without continuous access to clean water are at higher risk.

Signs and Symptoms of Ulcers in Horses

Ulcers in horses rarely produce dramatic acute symptoms. The signs are subtle, easy to mistake for behavioural problems, and often appear gradually.

Behavioural Signs of Ulcers

• Girthiness: pinned ears, biting, swishing tail or trying to move away when the girth is tightened.
• Resistance to being saddled or rugged.
• Bucking, rearing or napping under saddle, particularly in upward transitions.
• Reluctance to move forward or lengthen the stride.
• Grumpy or aggressive behaviour around feeding time.
• Yawning, lip-licking, teeth grinding (bruxism).
• Stretching out as if to urinate without producing urine.

Physical Signs of Ulcers

• Dull, staring coat that does not respond to feeding or grooming.
• Picky or inconsistent appetite, especially leaving hard feed.
• Slow weight loss or loss of topline despite adequate calories.
• Recurrent mild colic, often soon after feeding.
• Loose droppings or fibre breakthrough in droppings (a sign of hindgut acidosis).
• Reduced performance, lengthening recovery times, dropping behind the bit.
• Sensitivity to brushing or palpation behind the elbow.

The challenge with ulcers is that no single sign is diagnostic. A horse showing four or five of the above warrants scoping. A horse showing one or two should be evaluated holistically: are there saddle-fit issues, dental pain, kissing spines or stomach disease driving the picture?

How Vets Diagnose Equine Gastric Ulcers

Gastroscopy is the gold standard and the only definitive diagnostic. A 3-metre flexible endoscope is passed through the nose, down the oesophagus, and into the stomach. The horse is sedated and fasted for 12 to 16 hours before the procedure – the window used in the published studies, and not longer, because fasting is itself a documented cause of squamous ulceration. The whole examination takes 15 to 30 minutes and is performed standing.

The vet grades squamous lesions from 0 (intact epithelium, no hyperkeratosis) to 4 (extensive lesions with areas of apparent deep ulceration) on the 1999 Equine Gastric Ulcer Council scale, which ECEIM endorses for ESGD only. There is no validated grading scale for glandular lesions: ECEIM recommends those be described by appearance and contour rather than given a grade, so a “grade 3 glandular ulcer” is not a meaningful reading. Crucially, the scope distinguishes ESGD from EGGD by location and appearance, which determines the treatment protocol.

Blood tests, faecal occult blood tests, and sucrose absorption tests have all been studied as alternatives. None is sensitive enough to replace gastroscopy. A trial of omeprazole (“therapeutic diagnosis”) is acceptable for cost-constrained leisure horses but should be reviewed within 28 days; failure to improve in that window strongly suggests EGGD, hindgut disease or another underlying problem.

Treatment of Ulcers in Horses

Treatment depends on whether the lesions are squamous (ESGD), glandular (EGGD), or both.

Treating Squamous Ulcers (ESGD)

The licensed treatment is omeprazole (GastroGard or Peptizole) at 4 mg/kg orally once daily for 28 days, followed by gastroscopy to confirm healing. Around 70 to 80 per cent of ESGD cases heal on this protocol. A reduced dose (1 to 2 mg/kg once daily) may then be continued, but it is a recurrence-prevention dose rather than a taper: it holds ulcers off only for as long as the horse stays on it, and horses taken off omeprazole at day 28 ended the study in the same state as horses never treated at all (Andrews et al., Equine Veterinary Journal Supplement 1999;29:81-86). The common instruction to taper for a fixed two to four weeks to head off rebound acid hypersecretion is not supported: serum gastrin returns to baseline within 2 to 4 days of the last dose, and the authors concluded that their results “do not support the use of tapering protocols in horses” (Clark et al., Journal of Veterinary Internal Medicine 2023;37:1537-1543). Whether to continue at all is a decision for the vet, not an automatic next step.

Once-daily dosing on an empty stomach gives the best absorption. UK retail price for a 28-day course is around £350 to £600 depending on dose and supplier.

Treating Glandular Ulcers (EGGD)

EGGD responds poorly to omeprazole on its own. The ECEIM consensus (the 2015 one) recommends omeprazole as for ESGD plus sucralfate at 12 mg/kg orally twice daily, and a minimum of 8 weeks of combination therapy before other agents are considered. Misoprostol is given at 5 micrograms/kg orally every 12 hours – twice daily, not three times a day; in the only trial to compare them head to head it out-performed omeprazole plus sucralfate, healing 72 per cent of cases against 20 per cent (Varley et al., Equine Veterinary Journal 2019;51:575-580). Misoprostol is a synthetic prostaglandin analogue borrowed from human medicine and is not among the substances listed as essential for equidae in Regulation (EC) No 1950/2006, so using it in a horse is a prescribing decision for your vet. Re-scoping is essential to confirm healing.

EGGD treatment is typically 50 to 80 per cent more expensive than ESGD due to longer courses and combination therapy. Some horses require ongoing low-dose maintenance.

Supplements and Supportive Care

Several UK supplements support gastric health alongside drug treatment.

• Pectin-lecithin complexes. Aimed at the squamous mucosa.
• Sea buckthorn berry products. Some evidence of mucosal protection.
• Marine-derived calcium and magnesium preparations. Acid-buffering effect.
• Alfalfa chaff. A small feed of alfalfa before exercise creates a fibrous mat that buffers acid splash during work. An alfalfa hay-and-grain diet raised gastric pH and produced significantly fewer and less severe squamous lesions than grass hay (Nadeau et al., American Journal of Veterinary Research 2000;61:784-790). One caveat before reaching for it on a glandular case: weanlings fed alfalfa chaff had significantly more severe lesions at the pylorus than those on grass hay (Vondran et al., BMC Veterinary Research 2016;12:110).

Feeding and Management to Prevent Ulcers

Drug treatment heals the lesions. Without management change, they come back within weeks. The protocol below is built from the risk factors identified in the ECEIM consensus and the Danish risk-factor study above. Neither the BHS nor BEVA publishes owner-facing ulcer-management guidance, so be wary of any feeding protocol presented as theirs.

1. Ad-lib forage. Aim for at least 1.5 to 2 per cent of bodyweight in forage daily. Use small-hole haynets, two or three nets at a time, to extend chew time without overfeeding.
2. Keep forage gaps under six hours. That is the interval the Danish study linked to squamous ulceration. Top up haynets before bed, before exercise, and on returning from a ride.
3. Feed alfalfa before fast work. A small feed of chopped alfalfa shortly before exercise creates a fibrous mat in the stomach. No trial has fixed the exact quantity or the exact interval, so follow the feed manufacturer’s rate or your vet’s advice rather than a number off the internet.
4. Cut starch. Replace cereal-based hard feed with high-fibre, high-oil alternatives. Keep starch under 1 g per kg bodyweight per meal; under 2 g per kg total per day.
5. Multiple small meals. Three or four small hard-feed meals beat one or two large ones.
6. Maximise turnout, ideally with company. In one study of Thoroughbreds in training, horses with some turnout were less likely to have ESGD, and less likely again if turned out with other horses. But ECEIM rates the overall evidence “conflicting”: other work found no effect of time at pasture, and no difference in stomach pH between a grass paddock and a stable. Turnout is worth maximising on its own merits – just treat “horses ulcerate less on grass” as unproven rather than a rule, and note that no study sets a daily minimum.
7. Provide social contact. Horses kept in isolation have higher ulcer rates than those with companions.
8. Constant access to clean water. Empty buckets between drinks; check automatic drinkers daily.
9. Minimise NSAID use. If long-term anti-inflammatories are needed for conditions like arthritis in horses, ask the vet about COX-2 selective alternatives such as firocoxib.
10. Reduce stress. Stable routine, predictable feeding times, gradual workload increases. Reassess yard routine if a horse ulcerates repeatedly.

Hindgut Ulcers and Colonic Disease

Beyond the stomach, the horse can also develop ulcers and inflammation in the colon and caecum, collectively called Right Dorsal Colitis (RDC) when chronic. Risk factors overlap with gastric ulcers (NSAIDs especially), but the presentation is different: intermittent colic, weight loss, low blood protein, fluid in the abdomen.

Hindgut disease cannot be diagnosed by gastroscopy. Faecal sand tests, ultrasound, abdominocentesis and blood protein levels are the working tools. Treatment focuses on removing the NSAID, increasing forage, adding psyllium husk for the sand component, and supportive nutrition. The condition is more difficult to treat than gastric ulcers and warrants referral to a specialist equine internal medicine service.

Ulcers UK and South Africa Treatment Costs

Approximate 2026 treatment costs, indicative only.

• UK gastroscopy: £250 to £450 depending on practice and travel.
• UK omeprazole 28-day course (4 mg/kg, 500 kg horse): £350 to £600 (GastroGard or Peptizole).
• UK combination EGGD treatment (omeprazole + sucralfate, 6 weeks): £700 to £1,200.
• UK insurance: Most policies cover gastric ulcer treatment if the policy was active before the diagnosis and if the condition is not pre-existing. Check the wording on chronic conditions.
• SA gastroscopy: R3,500 to R6,500.
• SA omeprazole 28-day course: R5,000 to R9,000 (Peptizole, Ulsazol).
• SA combination EGGD treatment: R10,000 to R18,000.

Compounded omeprazole from veterinary pharmacies is cheaper but bioavailability varies widely between products; the licensed oral pastes named above have the strongest evidence base.

Frequently Asked Questions

How do I know if my horse has ulcers?

The most reliable test is gastroscopy. Indirect signs include girthiness, pinned ears at saddling, picky appetite, dull coat, recurrent mild colic and reduced performance. Any horse showing four or more of these signs should be scoped.

Can ulcers cause back pain in horses?

Yes, indirectly. Horses with painful gastric ulcers often guard the abdomen, alter their posture under saddle, and develop secondary muscle soreness in the back and shoulders. Owners commonly report back pain that resolves only once the ulcers are treated. Saddle-fit issues and ulcers frequently co-exist; both must be addressed.

How long does it take for ulcers to heal?

Squamous ulcers (ESGD) heal in roughly 70 to 80 per cent of horses over a 28-day course of omeprazole at 4 mg/kg. Glandular ulcers (EGGD) need combination therapy, and ECEIM advises completing a minimum of 8 weeks of it before other agents are considered. Re-scoping at the end of treatment confirms healing; clinical signs alone are unreliable.

Can stress cause ulcers in horses?

Yes. Transport, change of yard, hospitalisation, weaning, illness, and intensive competition campaigns all raise cortisol, reduce mucosal blood flow and predispose to both ESGD and EGGD. Stress is the leading suspected driver of glandular disease.

Will ulcers come back after treatment?

Yes, frequently, unless management changes alongside drug treatment. Studies show 40 to 60 per cent of treated horses re-ulcerate within 90 days if forage, turnout, starch and exercise routine remain the same. Drug treatment without management change is a waste of money.

Can horses eat normally with ulcers?

Most can, but appetite is often patchy. Some horses leave hard feed entirely. Forage tends to be eaten more reliably than concentrate. If a horse loses appetite completely, contact the vet; total anorexia is more consistent with severe ulceration, choke, or another acute problem.

Is alfalfa good for ulcers?

Yes. Alfalfa hay or chaff buffers gastric acid through its calcium and protein content and the fibrous mat it creates in the stomach. A handful 30 minutes before exercise reduces splash damage to the squamous mucosa. Alfalfa is most useful as part of a forage mix, not as the sole hay.

For related care information see our guides to coughing in horses, horse body condition scoring, and equine Cushing’s disease.