Kentucky Derby winner Medina Spirit’s cause of death undetermined

A necropsy performed on Kentucky Derby winner Medina Spirit, who died at the end of a workout at Santa Anita Park racetrack in December, failed to determine a definitive cause of death, the California Horse Racing Board announced Friday.

“The definitive cause of death of this horse was not determined after post-mortem examination and extensive laboratory testing,” according to a necropsy done on the 3-year-old colt following his Dec. 6 death.

State officials say the necropsy found an anti-ulcer medication and a diuretic in the 3-year-old colt’s system, consistent with earlier reports, but “no other drugs, heavy metals or toxicants were detected.”

“Considered altogether, the results of the post-mortem examination, histopathology, and ancillary testing, are supportive of a sudden cardiorespiratory arrest as it may occur with acute cardiac failure,” according to the necropsy’s findings, which noted that “mild to moderate” degenerative joint disease was found in the colt’s fetlock and elbow joints but was “unrelated to the cause of death of this horse.”

Two experts reviewed the report, including photographs of the horse’s organs, writing that they agreed with the conclusion of an undetermined cause of death.

“Cases of sudden unexpected death in racehorses are frustrating to deal with, and frequently remain unresolved, as in this case,” Dr. M. Grant Maxie, who is retired from the University of Guelph in Canada, wrote in a letter. “Marked acute pulmonary congestion and edema in this case is consistent with acute heart failure … I agree with the final diagnosis of `Cause of death: undetermined; sudden cardiorespiratory arrest/cardiac failure suspected.”

Dr. Laura A. Kennedy, associate professor at the University of Kentucky Veterinary Diagnostic Laboratory, added that the findings of pulmonary edema and congestion are “common in cases of sudden death, and do not rule-in nor rule-out a particular cause.”

In a statement released shortly after the horse’s death, track officials said, “Following the completion of a routine morning workout, Medina Spirit collapsed on the track at Santa Anita Park and died suddenly of a probable cardiac event according to the on-site veterinary team who attended to him.”

A veterinarian, a safety steward and a member of the Board of Stewards will participate in the review of the necropsy report as required under a CHRB rule, officials noted.

The horse, trained by Bob Baffert, won the Kentucky Derby last May but later tested positive for the steroid betamethasone, leading to challenges to the validity of the victory. Officials at Churchill Downs announced that Medina Spirit would be disqualified if the test was confirmed, and it suspended Baffert for two years.

Baffert and his attorney have insisted that the positive test was the result of a topical ointment known as Otomax being used to treat a skin condition, not an injection aimed at enhancing the horse’s performance in the race.

Medina Spirit — who earned just over $3.5 million — had five wins in 10 starts, including the Robert B. Lewis Stakes and the Awesome Again Stakes at Santa Anita, the Shared Belief Stakes at Del Mar and the Kentucky Derby, and never finished worse than third in any race. He was second to eventual Horse of the Year winner Knicks Go in the Breeders’ Cup Classic at Del Mar on Nov. 6.

Medina Spirit was one of three finalists for the Eclipse Award for a 3- year-old male, garnering 84 votes compared with 131 for Essential Quality, who won the award Thursday night in a ceremony at Santa Anita.

The animal-advocacy organization PETA had called for a thorough investigation of Medina Spirit’s death, and urged action against Baffert, saying seven horses he was training have died in a 16-month period.

In a statement released after the necropsy report was released, PETA’s senior vice president, Kathy Guillermo, said, “How many Bob Baffert- trained horses will drop dead with no known cause before he is booted out of racing? We urge the California Horse Racing Board to retain blood and urine samples from the horses, as new tests to detect as-yet unknown doping agents are likely to be developed.”

Clark Brewster, an attorney for Baffert, issued a statement saying Medina Spirit’s death “was not preventable.”

“We were hopeful that the necropsy would have revealed more information about the pathophysiology that led to Medina Spirit’s sudden cardiac arrest, but it appears that his tragic death was an act of God and was not preventable,” Brewster said. “As was expected, the necropsy results were compatible with sudden cardiac death and were consistent with reports of similar events of sudden death during workouts.

“Investigators determined that a possible defect in Medina Spirit’s cardiac conduction system, which regulates electrical activity in the heart, is a possible explanation. Extensive toxicological testing on multiple samples found no unexpected substances and nothing to suggest that Medina Spirit’s cardiac arrest was caused by the use of medications,” he said.

Dr. Francisco Uzal, a pathologist who oversees the necropsy program for the CHRB, said during a conference call with reporters, “From a diagnostic standpoint, this case is closed. Samples have been saved so if some new technology were to come to light in the future we can always go back to our freezer and get those samples.”

He noted that it was “absolutely frustrating” that the diagnostic team was unable to conclusively determine what caused Medina Spirit’s death.

The CHRB noted that an international study found that a cause of death was determined with certainty in approximately 53% of cases involving exercise-related sudden death in racehorses, with a presumptive cause established in 25% and a specific cause not able to be determined in the remaining 22%.

“Sudden death in racehorses has been extremely frustrating for a long time, not just in California, but throughout the U.S. and across the world,” said Dr. Ashley Hill of California Animal Health and Food Safety. “And, you know, it’s a recognized issue that there are horses that just drop dead during or shortly after exercise, and it’s been extremely frustrating to try and figure out what’s going on …. There is a lot of interest in trying to identify what the mechanisms behind this could be.”

She noted that there is ongoing research looking at genetic and cardiac factors that could be contributing to sudden death in horses.

“… There’s a lot of interest in trying to figure out what’s going on and ultimately prevent this from happening because nobody wants to see a horse go down like Medina Spirit did,” Hill added.