The USDA’s Animal and Plant Health Inspection Service (APHIS) announced on Friday (April 14) the use of gas chromatography/mass spectrometry (GC/MS) to enforce the Horse Protection Act (HPA). The method will detect horses that have been subjected to soring.

Since 2004, APHIS’ animal care program has held public meetings and informed horse industry organizations regarding the implementation of GC/MS technologies. USDA officials say this tool will aid APHIS’ efforts to detect the practice of soring, a cruel and inhumane practice used to accentuate a horse’s gait. Soring may be accomplished by irritating or blistering a horse’s forelegs through the injection or application of chemicals, mechanical devices, cuts, lacerations or burns.

APHIS’ animal care program is responsible for enforcing the HPA. The HPA is a federal law that prohibits horses that have been subjected to soring from participating in auctions, exhibitions, sales, or shows. The HPA also prohibits the transportation of sored horses to or from any of these events.

GC/MS is a testing technique used to identify the composition of chemical mixtures, which are sometimes applied to horses’ legs. APHIS collects the samples at shows and sends them to USDA’s National Veterinary Services Laboratories (NVSL) in Ames, Iowa, where testing is conducted to identify any chemicals in the samples. GC/MS can detect minute amounts of substances. Prior to GC/MS analytical techniques, foreign substances were detected by sight or smell.

The testing procedures and enforcement actions are as follows:

  • APHIS veterinary medical officers will swab horses randomly at every sale or show they attend for the remainder of 2006.
  • Swab tubes will be labeled by class and exhibitor number, and that information will be compared to the class sheets provided by show management or a horse industry organization to determine the owner, custodian, trainer, and exhibitor.
  • Swabs will undergo testing at NVSL for the presence of foreign substances via mass spectrometry analysis.
  • Any analysis that indicates the presence of a foreign substance will result in APHIS issuing an official warning letter, known as an APHIS Form 7060, signifying a violation of federal regulations to the owner, custodian, and trainer of all affected horses, as well as the exhibitor of the horse swabbed for samples taken “post show.”

A summary of the test results will be available on the HPA Web site at The summary will name the show, its location (city and state), show date, the number of entries, the number of swabs done for analysis, the number of foreign substance(s) detected, the names of the foreign substance(s) detected, and the percentage of swabs that contained the identified foreign substance(s).

Horse industry organizations have been made aware of this new enforcement measure, and any additional enforcement methods will not be utilized without prior notification to industry representatives and industry publications.

For more information on APHIS’ horse protection program, please visit