The Southern California racetrack, well-known for historical wins by way of thoroughbred greats including Seabiscuit, John Henry, and Zenyatta, is suffering to explain a series of fatal injuries in horses. In much less than three months, 22 horses have died on the Santa Anita tracks in Arcadia, most of them from catastrophic limb fractures, leading managers to close it down on 14 March. The string of fatalities has spurred outcries from animal welfare activists and triggered the first monetary loss—however, it additionally mystifies scientists who examine horse racing and racetracks.

Some believe heavy rainfall may have triggered abnormal compaction of the dust track layers, growing the fracture hazard when horses’ hooves penetrate the floor at excessive speeds. “Dirt tracks are in particular risk due to the fact they could appear best on the surface; however, conceal the compaction deep below,” says Nathalie Crevier-Denoix of the French National Institute of Agricultural Research and the National Veterinary School in Alfort, near Paris. However, a battery of assessments by U.S. professionals has failed to expose anything unusual.

Injuries are so extreme they cause death or require immediate euthanasia because they can not be repaired on every racetrack. The maximum not unusual type is a fracture of the front fetlock, a hinge joint among the foot, and the decreased leg bones that are “a vital surprise absorber, like aircraft landing equipment,” says Susan Stover, a veterinary researcher at the University of California, Davis. The catastrophic damage price has doubled at Santa Anita compared to the final year.

A horse’s age, intercourse, and racing reveal can all affect its hazard of harm, as can preexisting pressure fractures. Some specialists also suspect veterinary tablets. Joe Pagan, president of Kentucky Equine Research in Versailles, these days found that furosemide, used to prevent airway hemorrhaging because of exertion, and omeprazole, a treatment for stomach ulcers, both affect calcium excretion and absorption, could theoretically weaken bones; the Stronach Group, which owns Santa Anita, currently said it might ban the use of medication on racing days. But Pagan says a connection to the accidents is “a huge stretch.

Others have cited that more than 90% of racehorses nationally have stomach ulcers, and the maximum is dealt with furosemide, so the medication’s consequences wouldn’t be constrained to Santa Anita. Instead, many scientists assume something about Santa Anita’s dirt music has to be to blame. After the 21st demise this season, the Stronach Group invited Mick Peterson of the Racing Surfaces Testing Laboratory, a nonprofit business enterprise in Lexington, Kentucky, to look at the trouble. Peterson ran chemical and x-ray diffraction research heading in the right direction samples, checking out, amongst different things, the soil’s density, moisture content material, and mineralogical traits. He also examined the consistency of the music’s layers.

The pinnacle layer, the cushion, is smooth and granular to hose down the pony’s foot’s impact; the one below, called the pad, is tougher and more compact, considering the extra “push-off ” of the hoof. (Below, which might be greater layers referred to as the hardpan and the base.) Horses probably modify to different surfaces so long as they are consistent, Peterson says, however accidents should result if the track characteristics alternate from stride to stride. His team added a gadget, towed in the back of an automobile, that mimics a galloping horse’s forelimb plunging into the track and collects information on deceleration, sliding floor elasticity, and electricity absorption. They also used floor penetrating radar to determine the depths of the layers every 10 centimeters and the music.

None of the assessments revealed something unusual. “There’s not anything that we recognize, based totally on what we recognize; it is incorrect with the music,” Peterson says. Santa Anita reopened its tracks on eleven March, after his consequences had been available; inside days, a 3-year-old filly sustained fractures in both forelimbs and was euthanized. The shutdown resumed. Peterson says modern trying-out methods ought to overcome the problems with moisture management on the dust song.

He says the cushion layer works satisfactorily when it incorporates about 14% water. Track managers have an array of strategies for coping with moisture, including sealing water out all through wet weather by rolling the floor in a single day or “harrowing” and watering the tune for the duration of dry climate to offset evaporation. However, moisture levels can exchange dramatically throughout a race day, particularly when heavy rainfall alternates with light solar and desert winds.

Similarly, Santa Anita’s grandstand casts a huge, evolving shadow throughout part of the dirt music. The departure of Dennis Moore, a pro floor manager who retired from Santa Anita in December 2018, may additionally have performed a role. However, it’s no longer clear how many practices have been modified on account of that. “If the renovation wasn’t perfect, which could have been an issue,” Peterson says. Peterson is now studying how well extraordinary control strategies work after rainstorms.

Necropsies of the fallen horses may also provide clues, revealing whether certain injury styles have been more unusual. Santa Anita officers failed to reply to Science’s request for remark. They have naturally decided they can’t look ahead to technological know-how to provide you with definitive answers. Moore has been delivered lower back as a consultant, and as Science went to press, Santa Anita changed into slated to reopen on 29 March.