The biggest racing state in the United States is on the verge of banning the anti-bleeding drug, furosemide, in key races.
The Kentucky Horse Racing Commission voted 7-5 in favour of the measure, which must now be approved by state lawmakers to take effect.
It is the first state in the US to ban the raceday use of the drug, marketed under the names Lasix and Salix.
The drug reduces the chance of bleeding in the lungs in horses during physical exertion. However, animals given the drug shed a large amount of water and can race up to 25 pounds lighter.
Supporters of the proposed ban say the move will improve the image of racing, but opponents fear for the welfare of racehorses, predicting more will pull up with blood coming from their noses.
The proposed regulation phases in the race-day ban in graded or listed stakes races, starting with 2-year-old horses in 2014.
While graded or listed stakes races comprise only a fraction of all Kentucky races, they do offer greater prize money.
Kentucky’s racing commission had considered a ban on the raceday use of the drug in all races, but that proposed was lost in a 7-7 vote in April.
The chairman of the Asian Racing Federation, Dr Koji Sato, welcomed the Kentucky move.
Sato said that the profile of Kentucky within US racing is such that the decision by the Kentucky Racing Commission will hopefully encourage other states to follow its example.
“In addition to being a great step forward for Kentucky itself this development carries the prospect of having wider influence in promoting drug-free racing in North America.
“Kentucky plays such a prominent role within US racing and breeding that I am hopeful that other states will follow the example which has now been set by the Kentucky Racing Commission.
“It is the Asian Racing Federation’s strongly-held belief that drug-free racing is essential.
“Ensuring the welfare of our horses, achieving a level playing field for competitors, keeping the trust and confidence of the public, protecting horses and jockeys from injury, promoting the strength and soundness of the breed – these are all very powerful considerations and they all point in the one direction, namely that horses must race free from the influence of medication.”