Tevis 2017 Veterinary Research Project

Posted Friday, July 28, 2017 10:07pm

Transabdominal Ultrasound as a Predictor of Horses Developing Metabolic Problems During a Ride


The Western States Trail Ride has partnered with Drs. Melissa Esser and Hal Schott from Michigan State University to conduct a quick and non-invasive ultrasound study on the abdomens of endurance horses. One of the missions of the WSTF is to contribute to veterinary research as part of our charter. It is our hope to get near 100% rider participation to substantiate and expand this physiological data base on competing Tevis horses.

The process will take place on the Friday before the ride, at 1 hour post-completion or elimination, and 2-4 hours post-completion or elimination.  I am available to answer any questions you might have about the implementation of the study (pstalley@yahoo.com), and Dr. Mike Peralez (msperalez@roadrunner.com) is also available to answer your questions regarding the implementation, design and results of the study itself.

Only in a ride like the Tevis Cup, which has a goal of continuing research, does an opportunity of this significance come along. We welcome the possibility to learn from the data that this study can produce.


Background: Endurance horses are challenged with varied terrain, high ambient temperatures, and prolonged bouts of exercise making them prone to life-threatening metabolic disturbances, termed the “exhausted horse syndrome”. Each year endurance rides experience a handful of equine fatalities, with most due to acute gastrointestinal distress (colic) associated with exhaustion. Many more horses also receive medical care, specifically intravenous fluid therapy, for treatment of exhaustion. Commonly, at referral centers and in the field, ultrasonography is used to characterize the cause of colic, including decreased or absent gastrointestinal motility (ileus). Prolonged exercise contributes to development of ileus (and colic) in endurance horses, as blood is shunted away from splanchnic circulation to exercising muscles for a prolonged period during the ride.


This study has been designed to investigate one of the top causes for 100 mile horses to fail to finish, which is the development of intestinal dysfunction (i.e. decreased intestinal motility, also termed ileus). Our efforts will help to expand our understanding of the development of ileus in endurance horses and determine if our techniques can be utilized in evaluation of horses at risk of developing intestinal dysfunction in the future.


Currently, transabdominal ultrasound is routinely performed in the hospital, and more recently, has become a larger part of the diagnostic abilities of the field equine veterinarian, easily utilized with a horse with colic. The intestines can be rapidly imaged in the lower flank region with skin contact only. We propose to evaluate small intestinal function, or lack thereof, in 100 mile horses that are both successful and those eliminated. We are trying to determine if this rapid and non-invasive diagnostic tool is predictive of horses developing metabolic problems during or after the ride, especially in those horses that may require subsequent aggressive medical treatment.


Procedures: This is a voluntary study in which riders can participate, and it is a non-invasive ultrasound study that should take no more than 5 minutes each time. The ultrasound scans would be performed 3 times for each horse: 1) the evening prior to the ride, 2) within 60 minutes after completion or elimination, and 3) 2-4 hours after completion or elimination. This study should neither impact how the ride is organized or interfere with the rider’s completion. We plan to have 4 teams of 2 people (one ultrasonographer, one recorder) prepared to assess horses at the three points listed above, to minimize or eliminate any wait time for the horses.


Each 5-minute ultrasound will consist of imaging in four locations: 1) stomach size will be assessed on the left side of the abdomen, 2) small intestinal diameter and motility will be assessed in the left inguinal region, 3) small intestinal diameter and motility will be assessed in the right inguinal region, and 4) the duodenum will be assessed for diameter and motility. Video clips (30 seconds) will be taken of the inguinal regions, and the duodenum, and stomach size will be assessed by determining (by counting the number of rib spaces) the caudal most aspect of the stomach wall.


Please consider partaking in this very worthy study. This study is designed to have zero impact on riders and horses during actual competition. Thank you for your thoughtful consideration.


Dr. Langdon Fielding’s blood research will not happen this year as the trail will be different thus rendering any blood value data useless for study and comparison purposes.


Chuck Stalley, 2017 Tevis Ride Director

Mike Peralez, DVM Tevis Head Veterinarian