Selenium overdose probably killed 21 polo horses, Florida’s top vet says

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The 21 polo horses that died last week shortly before they were to compete in the U.S. Open polo tournament fell victim to a fatal overdose of selenium, a mineral ingredient in a medication meant to help them recover from exhaustion, according to Florida’s state veterinarian.

‘Signs exhibited by the horses and their rapid deaths were consistent with toxic doses of selenium,’ Dr. Thomas J. Holt said today of the circumstances surrounding the loss of the horses, which were all owned by the Venezuela-based Lechuza Caracas team.

The medication was prepared by an Ocala, Fla., retail and compounding pharmacy called Franck’s Pharmacy at the request of the veterinarian who treated Lechuza’s horses while in Florida. Franck’s Pharmacy announced last week that an internal review prompted by the horses’ deaths showed that the compound, a substitute for a medication called Biodyl that is unapproved for use in the U.S., was mixed incorrectly. The specific ingredient believed to have killed the horses was not publicly released until today.

It’s not yet known whether the team’s veterinarian specified an incorrect selenium amount in the prescription or if a pharmacy error was to blame for the dosage mistake. The veterinarian has not been named.

Biodyl was reportedly given on a weekly basis to the Lechuza horses while in training in Venezuela. ‘It’s used to help these horses, not make them super-horses,’ Dr. Rob Boswell told the South Florida Sun-Sentinel of the drug, which is legal and widely used in many countries outside the U.S., including Venezuela.

Although selenium is a naturally occurring mineral, it’s not normally given in supplements since most people and animals get an adequate amount of it through the food they eat, Texas A&M University toxicology professor Dr. Murl Bailey told the Associated Press. And, sadly, the overdose probably caused the horses quite a bit of discomfort before they died, the AP reports:

Bailey said an overdose of selenium can cause the veins in the body to dilate, ‘so there’s really no blood coming back to the heart.’

‘The horses go into shock,’ he said.

Necropsies previously revealed bleeding in the horses’ lungs.

Dr. Tam Garland, division head of the toxicology and drug testing section at Texas A&M’s Veterinary Medical Diagnostic Laboratory, said the horses’ deaths would likely have been painful, and irreversible after the overdose.

‘Hemorrhaging in the lungs tells me these horses couldn’t breathe,’ Garland said.

The laws that apply to mixing compounds to replicate medication that’s illegal in the U.S. are murky; it’s unclear whether Franck’s Pharmacy violated any law by providing Lechuza with the Biodyl substitute.

Investigations are underway by both the FDA and Florida state authorities.

-- Lindsay Barnett

Top photo: Argentine veterinarian Felix Eduardo Crespo feeds a horse at the Lechuza Caracas ranch in Wellington, Fla. Credit: Steve Mitchell / Associated Press
Bottom photo: Two attendees embrace during a memorial service held for the fallen horses on the International Polo Club grounds last week. Credit: Joe Raedle / Getty Images