Tevis Research Evaluates Horses' Blood Chloride Levels

Tevis Research Evaluates Horses' Blood Chloride Levels

“The lower chloride levels are associated with a loss of chloride from sweating and an indirect measure of the decrease in blood volume,” explained Fellers.

Photo: Anne M. Eberhardt/The Horse

During the 2012 Tevis Cup 100-mile endurance ride, Langdon Fielding, DVM, Dipl. ACVECC, of Loomis Basin Equine Medical Center, in California, and head Tevis veterinarian Greg Fellers, DVM, oversaw a research project aimed at improving veterinarians' ability to quickly and accurately identify horses in danger of metabolic failure. And the team is back again this year to further that research.

A preliminary analysis of data taken last year from approximately 176 horses at the 36-mile checkpoint, Robinson Flat, showed that lower chloride values in the blood were associated with a horse’s failure to complete the event.

“This research project looked to answer two questions,” Fellers said. “Is it possible to sample on-site during a competition and run results within an hour hold? Second, is there something in the blood work that can help officials identify a horse that might have trouble coping with the exertion of the ride and be unable to complete?”

The research team tested blood samples for packed cell volume, plasma protein, acid/base balance, and electrolytes. They also looked at recorded physical exam parameters such as heart rate and capillary refill recorded at the same 36-mile check point; however, none of those were associated with future problems.

“The lower chloride levels are associated with a loss of chloride from sweating and an indirect measure of the decrease in blood volume,” explained Fellers.

The researchers' ultimate goal is to create a metabolic score based on field blood work and to improve event completion rates and prevent injury to the horses. For now, Fellers believes, the greatest application will be for treating veterinarians who can pull a blood sample on a metabolically unstable horse and understand the significance of a low chloride level.

This year, the research team will attempt to replicate their results from 2012 and double their sampling numbers to further determine the predictive value of their data. The 2013 Tevis Cup will take place July 20. 

About the Author

Marsha Hayes

Marsha Hayes has been covering endurance, trail, and other equine topics since 2005. She believes every horse has a story.

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