By Dr. Cathy Barnette
Dr. Barnette is a paid Consultant for Covetrus®

You and your clients know that digestive conditions are a common cause of morbidity and mortality in horses. This is especially true in performance horses, in which gastrointestinal issues are associated with common management practices and can have significant impacts on athletic performance.¹ A client who understands digestive health is in a better position to care for their horse; therefore, client education is a key component of equine digestive health. As you conduct wellness visits, find time to educate your clients about equine gastric ulcers and hindgut health.

Equine gastric ulcer syndrome (EGUS) can affect any horse, but it presents a significant risk in performance horses. Only 11% of pet “backyard” horses demonstrate evidence of EGUS, while up to 58% of show horses and nearly 100% of racehorses are affected.²

The diagnosis of EGUS is often delayed, because vague clinical signs may be missed by owners and trainers. The owners of high-risk horses should be trained to monitor their horses closely for signs of EGUS, which may include weight loss, bruxism, mild/recurrent colic, abdominal discomfort after eating, training reluctance, behavioral changes, stereotypic behaviors, chronic diarrhea, and poor body/coat condition.^1-3 Any of these signs warrant a veterinary evaluation.

Performance horses should be routinely screened for this condition via endoscopic evaluation of the esophagus, stomach, and proximal small intestine.² Even endoscopy may underestimate the prevalence of EGUS, but it is the best diagnostic test available at this time.³ Ulcers should be inspected visually, with findings documented using a recognized scoring system.^1,2

Some clients may request empirical treatment for EGUS, in place of endoscopy. This is a not recommended, for several reasons. First, the treatment of EGUS can be costly. More importantly, however, treatment protocols vary depending on ulcer location. Equine squamous gastric disease is typically treated with omeprazole or other antacids, while glandular disease often responds poorly to antacids and requires sucralfate.¹ Obtaining an accurate diagnosis is essential to appropriately treat EGUS.

Management changes can help prevent EGUS. Long-term, low-dose omeprazole may be beneficial, but lifestyle changes are likely to have a greater impact.¹ Work with your clients to increase the amount of time that horses have access to pasture, while decreasing the amount of time horses spend stalled. If a horse must be fed grain or a concentrate, aim for small, frequent meals to minimize dramatic changes in gastric pH.¹ Working with your client to enact these changes, when possible, can reduce or eliminate the need for long-term antacid use. 

Equine hindgut health: Our understanding of the equine hindgut microbiota has evolved over time, from the initial characterization of cecal protozoa in 1843 to the identification of gastrointestinal archaea in 1996.⁴ Ongoing scientific advances have improved our understanding of the wide variety of fungi, parasites, protozoa, archaea, viruses and bacteria found in the equine hindgut and better identify the roles played by these organisms.⁵

Diversity of the gastrointestinal microbiota is a key factor in equine health. Horses with gastrointestinal disease typically have a less diverse gastrointestinal microbiota than healthy horses, with fewer species found within their intestines.⁶ The Firmicutes to Bacteroidetes ratio (F/B), a marker of gut dysbiosis, has been observed to be higher in horses with small and large intestinal colic than in healthy horses.⁶ An increased prevalence of Lachnospiraceae and Lactobacillaceae in the intestines has been observed in horses with large intestinal colic, and colitis is also associated with an unbalanced gastrointestinal microbiota.^5,6

Hindgut flora disturbances can often be traced directly to equine management practices. Horses on pasture typically have a more diverse gut microbiota than horses that are housed in a barn and fed a diet high in grain.⁵ Therefore, promoting hindgut health requires similar management changes to those recommended for the prevention of EGUS, with a greater emphasis on pasture foraging when possible.

Clients should be educated about these factors, so they can make the best decisions for their horse’s health. When management situations cannot be changed, probiotics can provide a valuable tool for restoring and maintaining the equine gastrointestinal microbiota. These probiotics, designed to withstand the hostile gastric environment, can reach and establish themselves in the colon for maximal benefits.⁵ When used correctly, probiotics can restore a healthy hindgut microbiota and promote overall equine health. 

Summary
As a veterinarian, there are many ways to support your patient’s gastrointestinal health. First, recommend gastroscopy in horses that are showing potential signs of gastric ulcers and in horses that are at high risk of this condition due to lifestyle. Additionally, educate your clients about these conditions and identified risk factors, helping them make management decisions that may reduce their horse’s risk. Finally, be prepared to treat EGUS and hindgut problems (such as colitis and colic) when they arise. By partnering with your clients and emphasizing gastrointestinal health from the beginning, you are in a better position to address problems early and proactively. 

About the author Cathy Barnette, DVM, is a veterinarian and freelance writer, based in Southwest Florida. After graduating from the University of Florida in 2006, Dr. Barnette spent 14 years working in small animal general practice. Her current professional focus is veterinary writing, creating educational content for veterinary teams and their clients. Dr. Barnette is a paid Consultant for Covetrus. 

REFERENCES

1. Andrews, F.M. (2021). How to Diagnose and Manage Gastric Ulcers as a Medical Reason for Poor Performance. AAEP Proceedings, 67. Retrieved from: https://aaep.org/sites/default/ files/2022-05/Andrews,%20Frank.pdf
2. Sykes, B. W., Hewetson, M., Hepburn, R. J., Luthersson, N., & Tamzali, Y. (2015). European College of Equine Internal Medicine Consensus Statement--Equine Gastric Ulcer Syndrome in Adult Horses. Journal of veterinary internal medicine, 29(5), 1288–1299. Retrieved from: https://onlinelibrary.wiley.com/doi/full/10.1111/jvim.13578
3. Andrews, F. M., Reinemeyer, C. R., McCracken, M. D., Blackford, J. T., Nadeau, J. A., Saabye, L., Sötell, M., & Saxton, A. (2002). Comparison of endoscopic, necropsy and histology scoring of equine gastric ulcers. Equine veterinary journal, 34(5), 475–478. Retrieved from: https://www.researchgate.net/publication/11099600_Comparison_of_endoscopic_necropsy_and_histology_ scoring_of_equine_gastric_ulcers
4. Julliand, V., & Grimm, P. (2016). HORSE SPECIES SYMPOSIUM: The microbiome of the horse hindgut: History and current knowledge. Journal of animal science, 94(6), 2262–2274.
5. Kauter, A., Epping, L., Semmler, T., Antao, E. M., Kannapin, D., Stoeckle, S. D., Gehlen, H., Lübke-Becker, A., Günther, S., Wieler, L. H., & Walther, B. (2019). The gut microbiome of horses: current research on equine enteral microbiota and future perspectives. Animal microbiome, 1(1), 14. Retrieved from: https://animalmicrobiome.biomedcentral.com/articles/10.1186/s42523-019-0013-3
6. Park, T., Cheong, H., Yoon, J., Kim, A., Yun, Y., & Unno, T. (2021). Comparison of the Fecal Microbiota of Horses with Intestinal Disease and Their Health y Counterparts. Veterinary sciences, 8(6), 113. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234941/