Looking back on all the endurance rides I have vetted in the last 10 years, I can't help but recall the many times I treated post-ride colic.

I was never sure what was causing these episodes but I did suspect equine gastric ulcer syndrome (EGUS), and began to experiment with simple management, treatment and prevention.

When the shockingly high prevalence of ulcers in the Thoroughbred racing industry was being studied I began to wonder whether endurance horses were as susceptible to ulcers. I felt the incidence was not as high as in other performance horses but was not sure.

There was no research to be found that only looked at endurance horses so I decided to start a research project which would inform and educate AERC members. I started researching three-meter gastroscopes to find one I liked which would suit the purpose and scope of the study.

Mike Murray, DVM, of the Virginia Tech School of Veterinary Medicine and Merial, Ltd., and one of the undisputed authorities on EGUS, taught me the particulars of scoping horses and diagnosing gastric ulcers. His expertise and assistance was invaluable.

We advertised in Endurance News to find people willing to have their horses examined for gastric ulcers as part of our study.

In the spring of 2003, with the help of AERC members across the country, we organized clinics in eight states representing eight AERC regions. Each clinic was scheduled for around 10 horses that were actively involved in endurance riding. The horses had to be actively training and competing to be eligible.

At the clinics, riders were required to answer an extensive questionnaire. The horses were sedated with xylazine and scoped. When ulcers were found they were graded using a four-point system: No ulcers: no ulcers found in the equine, Grade 1: hyperemia and hyperkeratosis, Grade 2: mild ulceration, Grade 3: bleeding coalescing deep ulcers.

My decision to use clinics rather than check horses at rides, which would be convenient and more economical, was twofold:

1. To examine the equine stomach adequately, sedation and fasting are most important, and contraindicated before or after a ride.

2. There are changes (simple temporary gastritis) associated with the participation in an endurance ride that can be misdiagnosed as EGUS. The goal of the study was to determine the incidence of EGUS in between rides.

There were no readily apparent variables that would pinpoint why EGUS occurs.

In all, 92 active endurance horses were scoped after being placed in stocks and sedated with 200 mg to 300 mg of xylazine HCL. A three-meter by 13 centimeter video gastroscope was passed through the equineÕs left nostril and into the stomach. Eight- to 12-hour fasting allowed good visibility of the interior of the stomach. The entire stomach lining was observed, including the pylorus and, in most cases, even the anterior duodenum. Abnormal findings were noted, graded and photographed. Treatment options were discussed with the owners. Of the 92 horses tested, 78 were Arabians, nine were Arab crosses, two were Thoroughbreds, and three were "other." They ranged in age from 4 to 20, with an average age of 10.8 years. Seventy-three were geldings and 19 were mares.

As suspected, gastric ulcers do occur in endurance horses. There was a 51.09% incidence of EGUS with from grade 1 to grade 3 lesionsÑ47 with and 45 without ulcers. Thirty-three horses (31.7%) had grade 2 and 3 ulcersÑwhat I call clinical lesionsÑand 11 (11.96%) had grade 3 bleeding ulcers.

These numbers are considerably lower than in Thoroughbred racing horses and lower than any of the other performance horse groups that have been studied previously. There were no readily apparent variables that would pinpoint why EGUS occurs. Questions were posed about the horses' training regimen, diet, temperament, trailering, etc. While there is a problem with EGUS in endurance horses, the problem is neither overwhelming nor unmanageable. I have had no trouble managing any cases that I have been asked to care for over the past several years.

If your horse has ulcers, removing the stress (stop competing), treating according to your veterinarianÕs recommendation, and then adopting a management program that reduces the incidence will allow you and your equine to get back to riding this wonderful sport.

Thank you to the AERC members who provided their horses as test subjects. Your time and effort are much appreciated.

A printable Excel spreadsheet containing all of the questions and a breakdown of the answers by numbers of equines and percentages of participants can be found at Ulcer Data Chart (Excel file).