Horse Ulcer Signs

Equine Gastric Ulcer Syndrome (EGUS) is one of the most prevalent and clinically significant conditions affecting horses worldwide. Studies and clinical consensus from organizations such as the American Association of Equine Practitioners (AAEP) and the Merck Veterinary Manual indicate that up to 90% of performance horses and over 50% of foals may suffer from gastric ulcers at some point in their lives. Despite this high prevalence, the signs of gastric ulcers can be subtle, variable, and easily mistaken for behavioral issues or other medical conditions.

This pillar article provides a comprehensive, evidence-based overview of horse ulcer signs, covering the pathophysiology of EGUS, the specific clinical indicators related to performance and appetite, diagnostic approaches, and prevention strategies. Whether you are a competition rider, a breeding farm manager, or a dedicated leisure horse owner, recognizing the early signs of gastric ulcers is critical for improving equine welfare and preventing long-term complications.

Quick Q&A

Question: What are the most common early signs of gastric ulcers in horses? Answer: The most common early signs include subtle changes in appetite (e.g., eating hay but leaving grain), mild colic after eating, decreased performance, and behavioral changes such as girthiness or resentment of the cinch. Many horses also exhibit a poor hair coat or low-grade weight loss. Early detection requires careful observation of feeding behavior and attitude.

Understanding Equine Gastric Ulcer Syndrome (EGUS)

EGUS is an umbrella term encompassing two distinct conditions: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). The stomach of the horse is divided into two regions. The squamous (nonglandular) mucosa lines the upper portion and is vulnerable to acid injury, while the glandular (lower) mucosa produces acid and protective mucus.

• ESGD: Primarily caused by prolonged exposure of the squamous mucosa to hydrochloric acid. This is often due to intermittent feeding patterns, high-grain diets, or intense exercise.
• EGGD: Involves inflammation and ulceration of the glandular mucosa. The pathophysiology is less understood but is linked to stress, nonsteroidal anti-inflammatory drug (NSAID) use, and bacterial factors (though Helicobacter pylori is not a primary agent in horses).

The Merck Veterinary Manual emphasizes that any horse can develop ulcers, but risk factors include intensive training, confinement, transport, hospitalization, and concurrent illness. The AAEP provides clinical guidelines stressing that diagnosis should be based on gastroscopy (endoscopy) rather than relying solely on clinical signs, as signs are often nonspecific.

Key Signs of Gastric Ulcers in Horses

Recognizing the signs of EGUS requires a systematic approach. The clinical presentation varies depending on the severity, location (squamous vs. glandular), and the individual horse's temperament.

1. Appetite and Feeding Behavior Changes

Changes in appetite are among the most reliable indicators of gastric discomfort.

• Selective eating: A horse with ulcers may eat hay or pasture readily but refuse grain or concentrates. This is thought to be because grain increases gastric acid production and may irritate ulcerated tissue.
• Slow eating: Horses may eat slowly, drop feed (quidding), or stop eating mid-meal.
• Poor body condition: Chronic ulcers can lead to weight loss, poor hair coat, and reduced muscle mass despite adequate caloric intake.
• Teeth grinding (bruxism): Especially in foals, grinding teeth can indicate abdominal pain.

2. Performance Decline and Attitude Changes

Performance horses are at high risk, and subtle performance issues are often the first sign noticed by riders and trainers.

• Reluctance to work: The horse may refuse to go forward, resist collection, or show a general lack of enthusiasm.
• Girthiness (cinchiness): Flinching, pinning ears, or biting when the girth is tightened is a classic sign. This is due to pressure on the abdominal wall overlying the stomach.
• Behavioral issues: Irritability, aggression toward handlers, or a dull, depressed demeanor. Some horses become anxious or spooky.
• Poor recovery: Horses may take longer to recover after exercise, with elevated heart or respiratory rates.

3. Colic and Gastrointestinal Signs

Low-grade, recurrent colic is common in horses with EGUS.

• Postprandial colic: Signs of mild abdominal pain (looking at the flank, stretching, pawing) often occur within 30 to 60 minutes after eating.
• Diarrhoea or loose manure: Some horses develop soft stools or diarrhoea, though this is more common with hindgut issues.
• Excessive salivation (ptyalism): Occasionally seen in foals or horses with severe esophageal irritation.

4. Physical Examination Findings

On veterinary examination, certain findings may raise suspicion for EGUS:

• Poor hair coat: A rough, dull coat is often noted.
• Capillary refill time (CRT): Usually normal, but may be slightly prolonged in chronic cases.
• Abdominal auscultation: May reveal decreased borborygmi (gut sounds) during a mild colic episode.
• Body condition score (BCS): Horses with chronic ulcers often score below 5 out of 9.

Regional Considerations: North America, Europe, and Australia

While the pathophysiology of EGUS is consistent globally, regional management practices and risk factors vary.

• United States and Canada: High prevalence in Thoroughbred and Standardbred racehorses, as well as Western performance horses (cutting, reining). The AAEP recommends gastroscopy screening for any performance horse showing subtle signs.
• Europe: The Federation of Veterinarians of Europe (FVE) and national equine veterinary associations emphasize the role of stable management (e.g., turnout time, forage availability). In the UK, leisure horses are increasingly diagnosed, possibly due to awareness.
• Australia: The Australian Veterinary Association (AVA) notes that horses on irrigated pastures may have lower risk, but those in intensive training or stabled for long periods are at high risk. The term "gastric ulcer" is used interchangeably with EGUS.

Spelling variations (e.g., "diarrhoea" vs. "diarrhea", "behaviour" vs. "behavior") are used throughout this article to reflect both American and Commonwealth conventions.

Diagnosis: Confirming Ulcers

Clinical signs alone are insufficient for a definitive diagnosis. The gold standard is gastroscopy (upper airway endoscopy performed under sedation). The AAEP and Merck Veterinary Manual both state that gastroscopy allows direct visualization of the squamous and glandular mucosa and grading of lesions (e.g., Grade 0 to 4 for ESGD).

• Preparation: The horse must be fasted for 12 to 16 hours to ensure an empty stomach.
• Procedure: A 3-meter endoscope is passed via the nostril into the stomach. The procedure is well tolerated with sedation.
• Findings: Ulcers appear as reddened, eroded, or cratered areas. Glandular lesions may be hemorrhagic or fibrinous.

Differential diagnoses include:

• Dental disease (causing quidding and weight loss)
• Hindgut acidosis or colonic ulcers
• Parasitism (e.g., cyathostomins)
• Chronic pain from orthopedic issues (causing performance decline)

Veterinarians may also perform a fecal occult blood test, but this is not specific. Response to treatment (e.g., omeprazole) can support a presumptive diagnosis when gastroscopy is unavailable.

Treatment and Management

Treatment aims to reduce gastric acidity, promote mucosal healing, and address underlying risk factors.

Medical Therapy

• Omeprazole: A proton pump inhibitor (PPI) that suppresses acid secretion. It is the only FDA-approved medication for EGUS in horses. The standard dose is 4 mg/kg once daily for 28 days, but higher doses may be needed for EGGD.
• Sucralfate: A cytoprotective agent that binds to ulcerated tissue. Often used in conjunction with omeprazole for glandular ulcers.
• Antacids: Short-acting and rarely used as sole therapy.
• Misoprostol: A prostaglandin analogue used for NSAID-induced ulcers, but with potential side effects (diarrhea, sweating).

The AAEP guidelines emphasize that treatment should be continued for the full duration, even if clinical signs resolve quickly.

Dietary and Environmental Management

• Forage-first diet: Provide free-choice hay or pasture. Forage buffers stomach acid and stimulates saliva production (a natural buffer).
• Reduce grain: Limit concentrates to no more than 0.5% of body weight per meal. Soaking hay or using low-starch feeds may help.
• Frequent feeding: Divide daily rations into multiple small meals. Avoid prolonged fasting (more than 6 hours).
• Turnout: Maximize pasture turnout. Continuous grazing is ideal.
• Stress reduction: Minimize transport, competition stress, and social isolation. Use calming supplements if needed.

Prevention Strategies

Preventing EGUS is far more effective than treating it, especially in high-risk populations.

• Feeding management: Ensure horses have access to forage at all times. If hay must be restricted (e.g., for metabolic conditions), use slow-feed nets.
• Grain reduction: Avoid feeding large grain meals. Use fat or fiber-based energy sources instead.
• NSAID caution: Use NSAIDs (e.g., phenylbutazone, flunixin meglumine) judiciously. Always provide with food.
• Supplementation: Some studies suggest that alfalfa hay (due to its calcium content) may help buffer stomach acid. However, this must be balanced with other nutritional needs.
• Regular gastroscopy: For high-performance horses, annual or biannual gastroscopy is recommended by the AAEP.
• Probiotics and prebiotics: Emerging evidence suggests that gut health supplements may support mucosal integrity, but more research is needed.

The Kentucky Equine Research (KER) organization emphasizes that prevention begins with understanding the horse's natural evolutionary need for continuous grazing.

Prognosis and Long-Term Outlook

With appropriate treatment and management, the prognosis for EGUS is generally good. Squamous ulcers (ESGD) often heal within 2 to 4 weeks of omeprazole therapy. Glandular ulcers (EGGD) may take longer (4 to 8 weeks) and have a higher recurrence rate.

Factors that worsen prognosis include:

• Chronic NSAID use
• Concurrent disease (e.g., pituitary pars intermedia dysfunction, PPID)
• Inability to modify management (e.g., racehorses in training)
• Severe or perforated ulcers (rare but life-threatening)

Recurrence is common if risk factors are not addressed. Long-term management with dietary changes and stress reduction is essential.

When to Call Your Veterinarian

Any horse showing persistent changes in appetite, behavior, or performance should be evaluated. Emergency signs include:

• Severe colic (rolling, sweating, high heart rate)
• Signs of shock (pale mucous membranes, weak pulse)
• Blood in the manure (melena) or vomited blood (hematemesis)

In foals, ulcers can be rapidly fatal. Signs include diarrhea, teeth grinding, salivation, and lying on the back. Immediate veterinary attention is required.

References

[1] American Association of Equine Practitioners (AAEP). Equine Gastric Ulcer Syndrome (EGUS) Guidelines. Available at: aaep.org. [2] Merck Veterinary Manual. Overview of Gastric Ulcers in Horses. Available at: merckvetmanual.com. [3] The Horse: Your Guide to Equine Health Care. Gastric Ulcers: Signs, Diagnosis, and Treatment. Available at: thehorse.com. [4] Kentucky Equine Research (KER). Nutritional Management of Gastric Ulcers. Available at: ker.com. [5] Federation of Veterinarians of Europe (FVE). Equine Welfare and Management Guidelines. Available at: fve.org. [6] Australian Veterinary Association (AVA). Equine Gastric Ulcer Syndrome: Clinical Update. Available at: ava.com.au. [7] VCA Animal Hospitals. Gastric Ulcers in Horses. Available at: vcahospitals.com. [8] DVM360. Equine Gastric Ulcer Syndrome: Diagnosis and Treatment Updates. Available at: dvm360.com. [9] Cornell College of Veterinary Medicine. Equine Health: Gastric Ulcers. Available at: vet.cornell.edu. [10] European Medicines Agency (EMA). Omeprazole in Equine Medicine: Regulatory Status. Available at: ema.europa.eu.