WEST PALM BEACH, Fla. -- Florida's top veterinarian, Dr. Thomas J. Holt, on Tuesday blamed the deaths of 21 elite polo horses on an overdose of a mineral that helps muscles recover from fatigue. Holt said toxicology tests on the dead horses showed significantly increased selenium levels. The horses from the Venezuelan-owned Lechuza Caracas team began collapsing April 19. A Florida pharmacy that mixed the supplements for the team said Tuesday that the strength of selenium was incorrect.
"Signs exhibited by the horses and their rapid deaths were consistent with toxic doses of selenium," Holt said.
The team was preparing to play in the sport's U.S. Open and was seen as a top contender.
Jennifer Beckett, chief operating officer for Franck's Pharmacy in Ocala, Fla., would not say whether the incorrect amount was specified in the veterinarian order or was a pharmacy error.
"We continue to cooperate fully with the authorities as their investigations proceed," she said. "We cannot discuss further details."
Lechuza had no comment on the toxicology report.
The polo team had hoped to get a compound similar to a name-brand supplement known as Biodyl. The supplement is used around the world but hasn't been approved by the Food and Drug Administration in the U.S.
Veterinarians often turn to compounding pharmacies like Franck's for medications that can't be found on shelves, but the dispensaries generally can only recreate unapproved drugs in limited circumstances, such as for health reasons.
The FDA and state authorities are investigating.
Biodyl is a supplement made in France by Duluth, Ga.-based animal pharmaceutical firm Merial Ltd. It wasn't clear how close Franck's mixture came to the name-brand drug. Lechuza said what they ordered was supposed to contain vitamin B, potassium, magnesium and selenium.
The injections provided by Franck's were given to the horses just hours before their deaths.
Dr. Murl Bailey, a toxicology professor at Texas A&M University's College of Veterinary Medicine & Biomedical Sciences, said selenium is a common mineral needed in small doses by humans and animals for growth and tissue stabilization. It can also help muscles recover from fatigue.
"It's a naturally occurring mineral in the Earth's crust," Bailey said. But he said it was generally not needed as a supplement since most people and animals get it in their food.
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.