Equine drug testing is a form of drug testing applied to performance horses in regulated competition. Most common in racehorses, drug tests are also performed on horses in endurance riding and in international competition such as the Olympics and FEI-sanctioned competition. Many horses in a competition sanctioned by various national organizations, such as the United States Equestrian Federation in the USA are also tested for improper drug use. An organization for cooperation and harmonization regarding horseracing is the International Federation of Horseracing Authorities (IFHA) that have several members in over 50 countries worldwide. Before the mid-1980s, the use of high potency performance altering substances in racing was less well controlled due to the inadequacy of analytical technology. Around that time, highly sensitive ELISA testing of horse urine was introduced to racing regulators by a group at the University of Kentucky. This proprietary technology essentially solved the problem of the abuse of high potency drugs in racing horses. ELISA tests are now marketed worldwide out of Lexington, Kentucky. Today, further advances in testing technology have augmented and in many instances replaced ELISA tests to detecting doping. Traces of therapeutic medications and dietary and environmental substances can be detected using current testing technology. This has created controversy over a "zero tolerance" approach to drug testing, and resulted in the establishment of regulatory limits or "thresholds" (the urine or blood concentration of a substance below which there is no pharmacological activity, i.e., there is no effect, a so-called "No Effect Threshold" or NET). Recent challenges in drug testing include the development of effective regulatory methods for the newer hormonal products such as the various human recombinant erythropoietin products and variants and growth hormones. A high-quality ELISA test for human recombinant erythropoietin is now available, and recently the first Mass Spectral Confirmation method to detect use of human recombinant erythropoietin (rhEPO) in horses or any species was developed. History The early history of horse doping is unclear, although according to Euripides (480-406 BC), some horses were fed human flesh to make them faster and more savage. However, during Roman times, the use of hydromel for chariot race horses was punished by crucifixion. The evolution of horse doping is less well known over the following millennia, but in 1666, the use of "exciting substances and methods" was prohibited at horse races in Worksop, England. In 1533, there were reports of a substance, probably related to