Michigan State University School of Veterinary Medicine has been a leader in research on colic in the long-distance endurance horse for a while.
Dr. Harold C. Schott II DVM, PhD, DACVIM, a member of the AERC Research Committee, and professor at MSU large animal clinical sciences, in association with the American Endurance Ride Conference, published a report in 2015 regarding 71 horse fatalities among the 270,070 starts in AERC-sanctioned rides during the years of 2002-14.
Schott found that fatality rates in endurance rides are low overall but increase with the length of the ride. The risk in limited-distance rides of 25-30 miles was 0.14 fatality per 1,000 starts. The risk increased by 10 to 1.46 fatalities per 1,000 starts in the 50- and 100-mile rides. Schott further reported that 75 percent of the horses that had a necropsy done had developed colic prior to their deaths.
Aware of this data, MSU is financing a team of researchers to collect data, including ultrasounds, on the horses in 100-mile rides. The research team was present — with equipment and staff — at the Big Horn 100 on July 15.
Dr. Melissa Esser, DVM and assistant professor at MSU, heads the team that also includes Dr. Lisanne Gallant, DVM and medicine resident at MSU, and Madison Dale, an undergraduate student.
Esser stated, “I chose five rides to do over the summer of 2017, the Big Horn of course, we’re here, the Bitmore Challenge Endurance race (Asheville, N.C) we did that in May, The Old Dominion (northern Virginia) in June, and of course we’ll be going to the Tevis Cup (Placer County, Calif.) and Virginia City (Virginia City, Nev.).”
Eighteen owners of horses competing in the Big Horn 100 signed up to be part of the research project. The team focuses on the 100-mile rides. According to Esser, “It’s those 100-mile rides that are challenging, that set the horses up for becoming dehydrated. These are the ones that we expect to see changes in their gut motility.”
Colic is a general word that means abdominal pain. In long-distance endurance rides the type of colic is not usually due to a mechanical obstruction of the gut but to metabolic factors. According to Esser, there is concern that the horse will develop an ileus with an inability of the intestine to contract normally and move waste out of the body. In a metabolic colic the intestines simply quit working. The fluid and gas formed from digestion will blow up the abdomen, cause abdominal pain and rarely cause a rupture of the intestine. This type of colic is brought on by a combination of dehydration, electrolyte loss and energy depletion.
The goal of the research is to identify factors that could promote early treatment of colic to prevent serious illness or death. “We’re looking at differences in motility at the beginning of the ride, to the end of the ride. We’ll look at the successful finishers and the unsuccessful finishers. This is a way to investigate and reduce that percentage,” Esser stated.
This was of particular interest to many riders of this year’s Big Horn 100. In 2016 at the Big Horn 100, a horse ridden by Linda Fisher — Kenlyn Arabians — from Denver, developed colic on the 100-mile ride and despite IV fluids died the day after the race. Five other horses developed less severe colic and were successfully treated. Dr. Essser states she was not aware of this ride’s recent history prior to the team’s arrival in the Shell Valley.
An ultrasound of abdomen, which takes about 15 minutes, was taken before the race, at the Battle Creek vet check and hour stop, at the finish line, and one last time the morning after the ride. Horses that went out via rider option or had been pulled by a veterinarian, and were competing in the 100-mile ride, were also checked.
Suzanne Hayes, Ovando, Mont., pulled her horse at Battle Creek. She noticed that Sanstormm, a gelding, had quit taking as many drinks and grabbing bites to eat along the way. At the rest stop he “kept pawing the ground with his foot and nosing its stomach.” Despite getting a B-plus rating on gut motility from the vet at that stop, she decided to pull.
Hayes has been riding endurance since the early 1970s. She has competed seven times in the Tevis as well as the Big Horn 100 numerous times. Hayes was one of five horse-and-rider teams chosen to represent the United States at the World Equestrian Games in 2010. She knows her horse.
Sanstormm was given some IV fluids at Battle Creek and then trailered back to the Picht ranch where the 100-mile ride began and ended. Waiting for him was the team of researchers.
Sanstormm had recovered some in spirit during that time. He had urinated, but was still dehydrated. The ultrasound showed that there was decreased motility in the intestines. Esser recommended that the horse not be fed anything that night. IV fluids were continued and he recovered with no known long-term effects.
Despite being disappointed at not finishing one of her favorite rides, Hayes said simply, “I’ll be ready to do it again.” Hayes is 63 years old.
The research team is headed next to the Tevis Cup (aka — The Western States Trail Ride) on Aug. 5-6. They will collect their last set of data at the Virginia City 100 on Sept. 16. The data will be analyzed and recommendations made. Riders who participated in the study will be sent a copy of their research conclusions, according to Esser. With this research the hope is early recognition and treatment of colic to reduce even further the small percentage of these long-distance equine athletes that might develop a metabolic colic during the event.
By Laurie D. Morstad