Undetectable drugs might have role in horse racing deaths

Horses prepare to race.
It’s unclear how much bisphosphonates are being administered to thoroughbreds, but the effects of the drugs can have a severe impact on the long-term health of the horse.
(Getty Images)

Horse racing has never experienced a year like this one. A spike of deaths at Santa Anita, Keeneland and tracks in New York, mixed with a controversial finish in the Kentucky Derby that prompted a lawsuit, have left the sport with a crisis-a-week feel.

This week, there is plenty more anxiety as attention turns to the Breeders’ Cup races, horse racing’s version of the Super Bowl. There will be 14 races, each with purses of at least $1 million, on Friday and Saturday at Santa Anita — over a track where there have been six horse fatalities in the last six weeks.

Thirty horses died during Santa Anita’s last winter-spring meet, and there was some speculation that the sport’s annual showcase might be moved to another venue. Santa Anita’s owner, the Stronach Group, responded to the crisis by enacting several reforms in medication usage and veterinarian care that will be used for the Breeders’ Cup races.

But experts are concerned about a drug treatment for which there are no rules, one used on some horses before they start racing, that might lead to more breakdowns and serious injuries.


In humans, bisphosphonates are used to treat osteoporosis. In young horses, they can alter the normal regeneration of bone and act as an analgesic — a pain reliever. And currently, their use cannot be traced.

A horse that has been treated with these drugs and is going to sale as a yearling or 2-year-old will have radiographs that can hide any sign of sesamoiditis, an inflammation of one of the lower bones of the leg. Plus, the analgesic effect will additionally hide any signs of lameness. The horse will look completely healthy.

“It’s a ticking time bomb,” said Dr. Dionne Benson, chief veterinary officer of the Stronach Group. “These medications keep me awake at night.”

One of the many problems with these drugs — commonly sold under the names Osphos and Tildren — is that they are only detectable in the blood for about 30 days, sometimes slightly longer. Their usage can’t even be detected in necropsies. Yet their effect can be long-lasting.

Santa Anita had a sixth horse fatality at the track since Sept. 18 when Bye Bye Beautiful, a 2-year-old filly, broke down Sunday and was euthanized.

Oct. 27, 2019

“If the sale is in September, you’re administering it from February to April,” said Dr. Mary Scollay, executive director and chief operating officer of the Racing Medication and Testing Consortium (RMTC). “Radiographs are taken 30 days out, so the treatment window is outside the window to detect.”

How widespread the usage of these drugs is remains unclear.

“I don’t think we will ever know,” Benson said, echoing a belief shared by Scollay.


“I don’t think there is a way to have an accurate understanding about how bisphosphonates have been administered to horses that are either racing or in training,” Scollay said.

The drugs were approved for use in horses in 2014, but only for those 4 and older. They are used to treat navicular syndrome, an inflammation or degradation of the navicular bone in the front feet that can cause a horse to go lame.

It’s the drug’s off-label use on young horses that has the equine medical community very concerned.

“These are medications for women with osteoporosis,” Benson said. “We’re not taking about people who are running full speed or have an Olympic-level regimen. For the horse, these can be used to make them sound and comfortable in the pasture or trail riding. Those are the kind of things these drugs are appropriate for. I don’t think you use it to get a horse ready for competition.”

“These medications [bisphosphonates] keep me awake at night,” said Dr. Dionne Benson, chief veterinary officer of the Stronach Group.
(THEPALMER/Getty Images)

Experts say a common misconception is that horses are being brought to the track too early and that they shouldn’t be raceduntil they are older. Science paints a different picture.

“Horses have to adapt their bones to the stress of racing,” Dr. Rick Arthur, chief equine veterinarian for the California Horse Racing Board, told The Times last year. “The bones are most adaptable when they are young. When they get older, the bone is not as responsive at 3 and especially at 4.”

An analogy would be to consider which building would be more likely to have less damage during an earthquake — one that has a lot of sway or one that is rigid? Older horses that have not gone through a bone remodeling process while younger are more prone to breakdowns.

Bones are constantly regenerating and creating new bone cells, more frequently in younger horses. During that process, there are cells that help to dissolve or break down bad or weak cells. Bisphosphonates inhibit that process, giving an appearance on radiographs that everything is OK with the bone when there is the possibility the bone has actually been weakened.

Those involved in trying to ban bisphosphonates are careful not to put motives on those who have administered the drugs. The lack of substantive research on the dangers might have led many to believe it’s OK to use the drugs on all horses.

“Commercial consigners will certainly do what’s best for a horse,” said Eric Hamelback, chief executive of the Horsemen’s Benevolent and Protective Assn. (HBPA) “If a medication helps in a certain situation, they will do it. But I don’t think anyone has done it nefariously.”

It remains to be seen how much time NBC will dedicate to recent horse deaths at Santa Anita as part of its 10-plus hours of Breeders’ Cup coverage.

Oct. 27, 2019

Hamelback compares the use of bisphosphonates to another class of drugs once accepted but now shunned.

“It reminds me of when people were using anabolic steroids,” Hamelback said. “There is a therapeutic use to it, but now you don’t see it used. It’s more of an education process that abolished anabolic steroids. … We’ve educated people and put it out there in the public that while anabolic steroids can be beneficial, it is more of a detriment, especially off-label.”

The RMTC board has approved language that will ban the use of bisphosphonates in horses younger than 4. It will be sent to the Assn. of Racing Commissioners International (ARCI), which sets rules and standards for horse and greyhound racing. The CHRB has a similar proposal set for its December meeting that would ban bisphosphonate use for any horse that has been administered the drug in the last six months.

The HBPA has also called for the banning of the drugs, and three sales organizations — Keeneland, Fasig-Tipton and Ocala Breeders’ Sales — are allowing horses to be tested for bisphosphonates. A positive test, if the buyer wants, would rescind the sale.

While there is widespread support to ban these types of drugs, it does little to mitigate the horses that have previously been administered them and are still racing.

“I’m not going to rule it out,” Scollay said about the increase in breakdowns and the use of bisphosphonates. “There are global concerns about bisphosphonates in your horses. To date, it is an unknown. It’s a troubling unknown.”