Gastric ulcers are a common yet often overlooked health issue in sport horses, affecting their performance, behavior, and overall welfare. The recently published study by Pineau et al. sheds light on the critical link between nutrition, gastric health, and ridden behavior in horses. By transitioning show-jumping horses to a low-starch, high-fiber diet, the researchers observed significant improvements in both gastric disease and pain-related behavior, highlighting the importance of tailored feeding strategies.

The Scope of the Problem

Equine Gastric Ulcer Syndrome (EGUS) encompasses two primary conditions: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). These conditions likely stem from different causes—excessive acidity in the stomach for ESGD and compromised mucosal defenses for EGGD. Gastric ulcers are especially prevalent in sport horses, with rates ranging from 17% to 58%, largely due to intense exercise, travel, and high-starch diets designed to meet energy demands. Clinical signs include poor performance, behavioral changes, and in severe cases, colic.

Despite the widespread prevalence, limited research exists on how gastric ulcers impact ridden behavior. This study aimed to bridge that gap, examining whether dietary changes could alleviate gastric disease and improve horses’ performance under saddle.

Study Design: A Cohort of Elite Athletes

The study involved nine Warmblood show-jumping horses housed at a professional stable. All horses followed a consistent training regimen and competed regularly in Fédération Equestre Internationale (FEI) events. Initially, the horses were fed a pelleted diet high in starch (29%) and sugar (2.5%). They were then transitioned to a low-starch (11%), muesli-type feed over 12 weeks. Alongside, their hay intake and feeding frequency were kept constant to ensure no confounding variables.

Comprehensive evaluations were conducted at the beginning and end of the study period. These included clinical exams, blood tests, gastroscopies to score gastric ulcers, standardized exercise tests (SETs), and assessments of pain-related behavior using the Ridden Horse Pain Ethogram (RHpE).

Key Findings: Healing the Gut, Easing the Ride

1. Improved Gastric Health
   At the outset, eight of nine horses exhibited gastric lesions, with a median total Equine Gastric Disease (EGD) score of 4 out of 8. By the end of the study, the median score dropped to 1, with two horses showing complete healing. Squamous and glandular ulcer scores both improved significantly, demonstrating that dietary intervention alone can promote healing without pharmaceutical treatments.
2. Reduced Pain-Associated Behavior
   The RHpE scores, which assess signs of pain during ridden exercise (e.g., head tilting, tail swishing, irregular gait), also improved. Median scores fell from 6 to 3, correlating strongly with the reduction in gastric ulcer severity. This finding underscores the link between gastric pain and behavioral changes, emphasizing the value of addressing gastrointestinal health to improve ridden performance.
3. Stable Fitness Levels
   The standardized exercise tests revealed no significant changes in heart rate, speed, or lactate levels, indicating that the horses maintained their fitness throughout the study. However, post-exercise lactate levels were slightly lower, suggesting better adaptation to exercise and reduced fatigue.
4. Enhanced Biochemical Profiles
   Blood tests showed reduced levels of muscle enzymes like creatine kinase (CK) and aspartate aminotransferase (AST), alongside increased vitamin E concentrations. These changes may reflect improved muscle health and antioxidant capacity, potentially linked to the diet’s higher digestibility and nutrient profile.

Why Diet Matters

The study reinforces the critical role of diet in equine health, particularly for horses in demanding athletic environments. High-starch diets have long been associated with gastric ulcers due to their impact on stomach acidity and microbial fermentation. Conversely, low-starch diets not only reduce acidity but may also promote gastric mucosal healing through:

• Improved pH Regulation: Reduced starch intake minimizes the production of volatile fatty acids, which can damage the stomach lining.
• Enhanced Saliva Production: The textured feed encouraged chewing and saliva production, helping to buffer stomach acid.
• Increased Nutrient Bioavailability: The cooked, flaked feed improved starch digestibility, reducing fermentation in the hindgut.

The inclusion of alfalfa (lucerne) chaff and prebiotic additives in the feed may have further contributed to the protective effects observed.

Practical Implications for Riders and Veterinarians

The findings highlight actionable strategies for improving the health and performance of sport horses. Key takeaways include:

• Transition to Low-Starch Diets: Gradual changes to a high-fiber, low-starch diet can significantly improve gastric health without the need for medications.
• Monitor Ridden Behavior: Behavioral changes, such as head tilting or reluctance to move forward, may signal underlying gastric pain and should prompt further investigation.
• Use Ethograms for Pain Assessment: The RHpE provides a valuable, field-friendly tool for identifying pain-related behaviors during exercise.

Limitations and Future Directions

While the study provides compelling evidence, its small sample size and focus on a specific population (elite show-jumping horses) limit its generalizability. Future research could explore the effects of dietary interventions across different equine disciplines and assess long-term outcomes.

Additionally, while the RHpE proved effective, more sophisticated tools could further elucidate the biomechanical impacts of gastric ulcers on locomotion.

Conclusion

This study underscores the impact of dietary management on equine gastric health and ridden behavior. By addressing the root causes of gastric ulcers, riders and veterinarians can enhance both the performance and well-being of sport horses. As the equestrian community continues to prioritize welfare, nutritional strategies will undoubtedly play a pivotal role in ensuring the health and welfare of performace horses.

Link to the study can be found here: Pineau V, Ter Woort F, Julien F, et al. Improvement of gastric disease and ridden horse pain ethogram scores with diet adaptation in sport horses. J Vet Intern Med. 2024;38(6):3297-3308. doi:10.1111/jvim.17223

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