arsenic, being used as a stimulant. After 1800 there is an uptick in the records of horses being prevented from competing (then called "stopped"), and in 1812 a stable boy was hung on Newmarket Heath for arsenic doping of a horse. In 1903, UK law prohibited horse doping and by 1912, saliva tests were introduced for horses which tested for alkaloids such as theobromine, caffeine, cocaine, morphine, and strychnine. In most major racing countries, positive results automatically disqualified horses. Doping took off, however, in the US in 1933 when pari-mutuel betting was legalized. Estimates suggest as many as 50% of horses were doped during this time, leading to a higher incidence of injuries caused by insensitivity to pain and lack of proper muscle coordination - the principal drugs of the era were cocaine, heroin, strychnine, and caffeine. In the later half of the 20th century, anti-doping efforts increased and became standardized by the FEI. A crackdown on horse doping in 2020 motivated congress to pass the first law establishing national regulations for the sport of horse racing. This law was Horseracing Safety and Integrity Act, which will also create a new enforcement agency to enforce the law. Types Horse Racing regulators in the United States divide drugs and medications into the following categories: Therapeutic medications Approximately 25 medications are now recognized by the Association of Racing Commissioners International (ARCI) for therapeutic use in race horses.</ref> Recent advances in technology resulting in high sensitivity testing continue to enable the detection of ever smaller trace concentrations of medications. This situation has led to the establishment of "thresholds" or "reporting levels," or "decision levels" (California) depending on the semantic preference of individual jurisdictions. These terms apply to the blood concentration of a medication below which it is believed by scientists and racing authorities that the medication has insignificant pharmacological effect. Thresholds (cutoffs) have long been used in human drug testing, however, the concept has been slow to be accepted by horse racing regulators who rely on the mere presence of a substance as a potential rule violation. Therapeutic medications (or drugs) are properly used to alleviate pain and to allow or promote healing. However, in the sport of horse racing powerful painkilling drugs may be used on a daily basis, often in combination with several other potent drugs, to enable injured horses to train and race before their injuries are fully healed. When