Technology commonly used to test blood for drugs and the air for pollutants may one day aid in the detection of chemical “soring,” the application of mustard oil, diesel fuel, kerosene or other irritating agents to a show horse’s legs to accentuate his gaits.

Gas chromatography, a method of isolating and analyzing volatile constituents using gas, shows promise as a method for identifying the use of soring substances, according to U.S. Department of Agriculture (USDA) veterinarians.

“At this point, [we are] testing this equipment and determining its applicability as a Horse Protection Act enforcement tool,” says Todd Behre, DVM, Horse Protection Coordinator for the USDA’s Animal and Plant Health Inspection Service (APHIS).

Also accomplished by mechanical means, such as pressure shoes, soring is a concern among many gaited breeds but is a particular problem at Tennessee Walking Horse events, where the high-stepping “big lick” running walk is prized. Soring is prohibited at shows and sales under the federal Horse Protection Act (HPA) of 1970, which is enforced by USDA inspectors and “designated qualified persons” (DQPs), who check horses at a sampling of shows each year.

Currently, soring is identified by observing the horse in motion, assessing stance and appearance, and conducting a physical examination, which consists of manual palpation of the lower legs, paying particular attention to the pastern area, coronet band and the bulb of the heel. However, says Behre, gas chromatography may prove to be a valuable additional tool.

Field testing of the technology began in April 2004, when USDA inspectors collected about 150 samples at two Tennessee Walking Horse shows. For each test a swab was swiped on the left and right pasterns of a horse and deposited in a glass vial for analysis using the gas chromatography machine.

Swabs found to have a foreign substance on them will be sent to another laboratory for identification. From these results, a “library” of illicit substances recognizable through gas chromatography can be established.

“This technology has a lot of potential, even just to disqualify [sored] horses and keep them out of the ring,” says Keith Dane, USDA liaison and past president of the organization Friends of Sound Horses. “If [gas chromatography] proves to be usable, testing for soring would be ironclad.”

This article originally appeared in the July 2004 issue of EQUUS magazine. Check out the November 2005 issue of EQUUS for a special report on the soring controversy.