New Study Finds Horses Racing On Lasix At 62 Percent Increased Risk Of Sudden Death

Paulick Report

A new study of data from the Equine Injury Database has revealed that horses medicated with furosemide (Lasix) on race day were at 62 percent increased odds of sudden death compared to horses that were not racing on furosemide.

Funded by the Grayson Jockey Club Foundation, the study was published by Dr. Euan Bennet and Dr. Tim Parkin on Oct. 20, 2022, in the Journal of the American Veterinary Medical Association. It examined the 4,198,073 race starts made by 284,387 Thoroughbred horses at 144 racetracks in the United States and Canada between 2009 and 2021; those numbers represent 92.2 percent of all official race starts during that period.

Of those nearly 4.2 million starts, 536 resulted in a horse’s sudden death, an incidence rate of 0.13/1,000 starts. Sudden death was defined as any horse that was recorded as a fatality within three days of racing, along with one or more of the following fatal injury descriptions or (presumptive) diagnosis, as provided by each participating track to the EID: (1) sudden death (recorded as “SUD” in the EID), (2) pulmonary hemorrhage, (3) exercise-induced pulmonary hemorrhage (EIPH), (4) postexertional distress/heatstroke (PED), and (5) cardiac arrhythmia.