A new study will examine the possible effects of combining furosemide, referred more often by its brand name, Lasix, and bisphosphonates in racehorses.
The study is being conducted by a team of 13 researchers at the University of Pennsylvania's School of Veterinary Medicine and is expected to be completed in about two years.
It will mark the first comprehensive analysis of the two drugs, which, when used together, could diminish bone integrity and compromise cardiac function in racehorses, according to a news release from Penn Vet. These effects can contribute to catastrophic injuries on the racetrack.
"By coupling our state-of-the-art imaging technologies with the scope of expertise among the other investigators on the project, we will be able to produce solid, unbiased data that will address some of the unknowns surrounding the use of these medications," Dr. Mary Robinson, assistant professor of veterinary pharmacology and director of Penn Vet's Equine Pharmacology Laboratory, said in the release.
Nearly 85 percent of racehorses in the U.S. receive Lasix as a preventive therapy for exercise-induced pulmonary hemorrhage. The drug causes a short-term loss of calcium. But horses can recover quickly from such a deficit, so Lasix alone is unlikely to be the root cause for catastrophic, racing-related breakdowns.
The effects of bisphosphonates are largely unknown, according to the release. They are intended to preserve bone integrity, but in young, growing animals, the drug may prevent bone from properly adapting to the forces applied during training, such as galloping.
And bisphosphonates can linger in the bone for at least a year, so there is a higher chance for interaction with Lasix for horses in training. Bisphosphonates also have been associated with increased risks of heart conditions in humans.
"Ultimately, we hope this research will empower us, as an industry, to make more informed decisions or exercise a greater degree of confidence in how we care for these animals that mean so much to us," Gretchen Jackson, a breeder and Penn benefactor, said in the release.
Jackson and her husband, Roy Jackson, owned Barbaro, who won the 2006 Kentucky Derby but shattered a leg two weeks later in the Preakness Stakes and died as a result.
The Penn Vet team will use advanced technology in the study, including standing robotic computed tomography (CT) and a new standing positron emission tomography (PET) system.
"This amazing imaging technology is going to be really instrumental in helping us assess the effects -- or lack thereof -- of these drugs on the bone," Robinson said. "It is the most sensitive technique that we have, from an imaging perspective, to look in detail at a horse's legs and see what's going on metabolically."
The study is supported in part by the Jacksons, the 2019 Eclipse Award-winning breeder George Strawbridge and his wife, Julia, and the Pennsylvania State Horse Racing Commission.