LEXINGTON, Ky. -- A group of racing companies that includes Churchill Downs, Keeneland, and the New York Racing Association are in discussions on a plan to prohibit the raceday use of furosemide in races for 2-year-olds and in stakes races, according to three officials with knowledge of the discussions. The plan, which could be announced as soon as this week, would go into effect for 2-year-olds in 2020 and then be expanded to all stakes at the tracks in 2021, according to the officials. As a result, if the plan goes through, the Triple Crown races held at Churchill Downs and Belmont, owned by NYRA, would not be Lasix-free until 2021. The plan has been hashed out among the tracks over the last few weeks in the wake of intense scrutiny of the racing industry brought about by a spate of fatalities this winter at Santa Anita Park in Southern California. Although raceday furosemide use has not been linked to fatalities, Churchill Downs and the New York Racing Association each host Triple Crown races, and the tracks are eager to counter the critical narratives buffeting the racing industry with an announcement that pushes back against the notion that the sport is too reliant on medication. Any restriction on raceday furosemide use is controversial among many rank-and-file trainers, and a Kentucky group representing that faction, the Kentucky Horsemen’s Benevolent and Protective Association, is almost certain to challenge the plan. That could take the form of a lawsuit seeking to invalidate the restrictions under an interpretation of Kentucky law that maintains that private companies cannot act as regulators. Furosemide, the only medication legal to administer on raceday in the U.S., is a diuretic used to mitigate bleeding in the lungs. The medication is banned for raceday use in most racing countries worldwide. Officials with knowledge of the plan commented on the condition of anonymity given the controversy surrounding raceday use of the medication. Officials for the tracks involved did not respond on Tuesday morning to phone calls. Last month, the owner of Santa Anita Park, The Stronach Group, and the state’s predominant horsemen’s group, the Thoroughbred Owners of California, agreed on a plan to phase out raceday use of Lasix beginning with the foal crop of 2018. Those restrictions will also be put in place at Golden Gate Fields, which is also owned by The Stronach Group. The Stronach Group also owns Pimlico, the site of the Preakness Stakes, the middle leg of the Triple Crown. Coverage of the Santa Anita deaths has underlined that raceday use of Lasix remains a convenient target for critics of racing, given the isolation of North America within the international racing community on the issue. However, many horsemen have privately expressed extreme displeasure with the efforts to restrict raceday use of the drug due in the wake of the Santa Anita deaths, saying that the two issues are unrelated and that supporters of a prohibition on raceday use have exploited the situation to press their case.    The Kentucky Horse Racing Commission is scheduled to meet at 1:30 p.m. on Tuesday. While it is possible the plan could be discussed at the meeting, it is not listed on the official agenda distributed on Monday.