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YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BY A43 TheHorse.com/AAEP2017 March 2018 THE HORSE AAEP Wrap-Up MICHELLE ANDERSON; ALEXANDRA BECKSTETT; STACEY OKE, DVM, MSC; CLAIR THUNES, PHD When Endurance Horses Colic: What Vets Need to Know ompetitive endurance riding chal- lenges a horse's athletic ability, stamina, and conditioning over rugged routes ranging from 50 to 100 miles. Because of the sport's strenuous nature, endurance horses are at risk for colic due to dehydration, fatigue, and metabolic disorders. Colic prevention, early intervention, and proper management during competi- tion can mean the difference between life and death for endurance horses, said Yvette Nout-Lomas, DVM, PhD, Dipl. ACVIM, ACECC, assistant professor of equine internal medicine at Colorado State University's (CSU) Veterinary Teach- ing Hospital, in Fort Collins. Nout-Lomas reported on a study in which she and American Endurance Ride Conference (AERC, the U.S. governing body for endurance) veterinary chair Jeanette Mero, DVM, of Mariposa Equine Services, in California, reviewed AERC data, including recorded equine fatalities related to endurance competition. During endurance rides, mandatory veterinary inspections take place be- tween ride phases (about every 15 miles) to ensure horses can continue safely. At these inspections, veterinary offi- cials evaluate heart rates, dehydration status, presence of gut sounds, and gait. Elimination is most commonly related to lameness, dehydration, and metabolic issues, Nout-Lomas said. The researchers found that of elimi- nated horses, 12% required emergency treatment. Most of these horses suffered from tying-up and colic. The AERC data indicated that ileus (slowed intestinal motility) and enteritis (inflammation of the small intestine) are the two most common causes of fatal colic in endur- ance horses. The endurance horse fatality rate from 2002 to 2016 was 0.026%, which Nout- Lomas noted is lower than most other horse sports. Still, she and Mero saw a need for veterinarians to better understand colic in endurance horses and how to treat it to improve outcomes. For example, she said, most colicking horses have elevated heart rates (some- times over 100 beats per minute) due to pain. However, endurance horses usually have superior fitness and/or naturally low heart rates, so even those with severe colic might not exhibit abnormally high heart rates. "Heart rates of 50 to 65 beats per minute (during a colic episode) are common," Nout-Lomas said. Also, Arabians, which are the most prevalent breed in endurance, are more susceptible to rectal tears than other horses. Dehydration might also increase rectal tear risk. So, the researchers rec- ommended avoiding rectal exams when conducting initial colic evaluations on Arabians or Arabian crosses. To address dehydration veterinarians should fluid-resuscitate horses early and aggressively with a balanced intravenous (IV) electrolyte solution, Nout-Lomas said. Clinical signs of dehydration could include a persistently elevated heart rate (more than 60 beats per minute 20 min- utes or more after stopping exercise) and anorexia, she said, noting that "horses with evidence of gastrointestinal (GI) disease or suspected to have GI disease should not be administered intragastric fluids due to concern of stomach disten- tion and possible fatal rupture." These horses are more likely to benefit from IV fluids, she noted. Dehydration also makes horses susceptible to kidney damage related to non-steroidal anti-inflammatory drug (NSAID) administration. For that reason, Nout-Lomas recommended avoiding NSAIDs for pain management in colicky endurance horses until a veterinarian is confident the horse is rehydrated. Gut Health: Preventing Gastric Ulcers and Colic ISABELLE ARNON