The Horseracing Integrity and Safety Authority has issued a request for proposals for scientific studies to establish whether furosemide, the diuretic administered in U.S. racing to mitigate bleeding in the lungs, should be defined as a “performance-enhancing” drug. The result of the study could have massive implications for the U.S. racing industry, which by-and-large allows for the race day administration of furosemide in most races outside of stakes and 2-year-old contests, contrary to raceday bans in nearly every other racing jurisdiction worldwide. Raceday use of furosemide, which is better known as Lasix, is heavily supported by most trainers and veterinarians, but its raceday use is controversial or opposed outright among some other domestic racing constituencies. Under HISA’s enabling legislation, the authority is required to issue a conclusion on raceday Lasix use by May 23, 2026. Last summer, also in accordance with its enabling legislation, HISA established an 11-member Furosemide Advisory Committee to review existing studies and conduct the groundwork to issue the 2026 recommendation. The request for proposals says that studies of the drug “must be sensitive to factors such as racing surface, age of horse, distance of race/exertion, environmental conditions such as humidity and altitude that may influence outcome, and/or the texture of the track surface.” The RFP further states that the study should “pay particular attention to the impact of the proposed work as it applies to racing in North America,” where horses are typically stabled in barns, often in urban areas, and subjected to environmental conditions that are not generally faced in Europe, where most horses are housed at private stabling yards in rural areas. The RFP says that HISA can award up to $1 million in funding for the studies. Previous studies on raceday Lasix use have shown that the drug is successful in mitigating bleeding in the lungs and that horses administered the drug prior to strenuous exercise perform better than horses that have not received an injection. However, those studies have not conclusively determined whether the drug is a “performance enhancer” to the satisfaction of many horsemen, who maintain that horses perform better under the influence of the drug because of its mitigation of bleeding. In that view, furosemide merely allows horses to perform to the best of their physical ability. The RFP says that studies will not be considered for funding without “an objective, quantifiable measure of performance.” The issue is further complicated by the position of animal-rights and animal-welfare groups, which typically support outright bans on any drugs administered on race day, under the argument that a horse that needs pharmaceutical help to perform is unfit to race. Opinion polls have also demonstrated that non-racing fans generally support bans on raceday drugs. However, horsemen who support raceday use contend that the use of furosemide is humane because it mitigates damage from a condition – exercise-induced pulmonary hemorrhage – that is common to equine athletes worldwide. Studies have also demonstrated that chronic bleeding in the lungs leads to long-term damage. Although raceday use of furosemide has long been banned in nearly every other major racing jurisdiction in the world, many horsemen in those jurisdictions acknowledge that horses who struggle with bleeding often receive Lasix treatments during training. HISA’s enabling legislation cited those bans in requiring that raceday Lasix use be banned three years after HISA’s first regulatory programs were launched unless the authority recommended otherwise. Technically, the act required the banning of Lasix at HISA’s launch, but it allowed racing states to apply for three-year exemptions allowing horses to be administered raceday injections of the drug outside of stakes races and 2-year-old races while HISA studied its final recommendation. All states applied for and received the exemptions prior to HISA’s launch. Under the RFP’s requirements, submissions for funding have a deadline of Oct. 15 of this year, with the Furosemide Advisory Committee deciding whether to fund the studies by Nov. 15. The completed studies will be required to be submitted to the FAC by Jan. 10, 2026. Nearly all the members of the FAC are veterinarians. The RFP prohibits the studies from being released publicly prior to Jan. 10, but it also states that the studies are “expected to be published in peer-reviewed journals” after the FAC makes its final determination on its recommendation on May 23, 2026. If the FAC does not issue a recommendation, a ban on raceday use of the drug will go into effect, as per the legislation. :: Want to learn more about handicapping and wagering? Check out DRF's Handicapping 101 and Wagering 101 pages.