Why a broken leg is a horse's death warrant.

Truest Reward was the thirty-eighth thoroughbred to meet its demise in 2019 at the Santa Anita racetrack. The high incidence of horses breaking their legs at this track in recent years has raised many concerns and adverse publicity.

Multiple factors are likely involved. They include not cancelling races when the track is rain-soaked and doping the steeds with anti-inflammatory drugs, sedatives, and muscle relaxants. Although toxicology studies have not shown drug levels that exceeded the racing board’s rules, it remains disturbing that the board allows horses to run while taking multiple medications. Such drugs likely mask early symptoms of skeletal stress, which are exacerbated by too-frequent racing–a habit promoted by those with strong financial stakes in the sport. The problem is not unique to Santa Anita. According to the Jockey Club’s Equine Injury Database, an average of nearly ten horses died while racing or training at American racetracks in 2018. Even more sadly, the same fracture can occur in horses not bred to race.

photograph by Eadweard Muybridge, about 1881
* = cannon bone
Link to Muybridge’s motion picture from 1887, which proved that at times all four feet of a running horse are in the air simultaneously.
The stresses on any one limb when it lands are tremendous.

Consider the long bones in your hand or forefoot. Imagine fusing two of the middle ones side to side, quadrupling their length, depriving them of any overlying muscle, and restricting their blood supply. Such are the cannon bones. They are a major reason why horses can run fast. But if the horse stumbles, gets kicked, or even tries to stand up in its stall, the cannon bone can break. The final snap may occur in a bone previously stressed and cracked, which was either unknown to or ignored by the trainer. Circulating medications may at times mask symptoms of the impending catastrophe.

The bones themselves are problematic. Most of these fractures occur in either the front or hind leg’s cannon bone. I have blogged previously on the versatility of these strong, dense, long bones that have been repurposed as chisels, awls, hide scrapers, buttons, chess pieces, decorative objects, musical instruments, and paving. What makes the cannon bone useful to crafts people makes them useful to horses.

Those affiliated with horse racing, financially, emotionally, or both, describe the final act as euthanasia, which is double speak for kill. With either word, the result is the same: the world is absent one magnificent animal.

*Whistlejacket* by George Stubbs, about 1762
**National Gallery**

So why is an equine cannon bone fracture fatal? Dogs and cats can hop around pretty well on three legs. Horses can’t. If they try, their other hooves become diseased. Casts and body slings are entirely impractical. Surgical fixation with metal plates and screws is sometimes attempted, but such procedures are complicated by several major issues. The fracture ends often tear the skin. Then bacteria-laden soil contaminates the wound. Infection overwhelms the surgical endeavor. The fracture may also strip the foot of its already tenuous blood supply, thus precluding the delivery of nutrients and antibiotics to the injury zone and beyond. Because of the added bulk, placement of sturdy hardware may preclude closure of the surgical incision. Then there is the issue of getting an 1100-pound patient to stand up following general anesthesia. The horse unknowingly and perhaps painlessly exerts tremendous bending and twisting forces that sorely test the stability of the most secure hardware fixation.

Is there hope? A little, especially for incomplete fractures and simple, non-displaced ones. Innovative veterinarian orthopedists can try to stabilize such fractures with screws placed through incisions just large enough to admit the drill, screw, and screwdriver. (three minute video) This is done with nerve blocks in the leg while the horse, awake, remains standing. (The surgeon and assistant perform the procedure on their knees.) Pool therapy, useful for sore tendons, ligaments, and joints in both humans and horses, may have a role in the rehabilitation of minor fractures that are securely fixed. Aquatic suspension may be particularly helpful during recovery from general anesthesia.

Since treatment is woeful and no improvements are on the horizon, hope has to rely on better regulation, which can’t come too soon. On New Years Day, Golden Birthday became the first Santa Anita racehorse in 2020 to meet Truest Reward’s fate from just five days before. And this is sport?