Buenos Aires  - The deaths in the United States of 21 polo horses belonging to the Venezuelan team La Lechuza Caracas caused a stir Tuesday in Argentina, the country of origin for most of the animals.

Argentina said it was considering testing the horses for doping.

An official investigation has been opened into the mysterious deaths of the animals, the United States Polo Association said Monday. The horses died just hours before a quarter-final match Sunday at the 105th US Open Polo Championship in Wellington, Florida. The tournament concludes South Florida's winter polo season.

"This can undoubtedly lead to the implementation of anti-doping testing in polo. It is expensive and hard to do it, but yes, it is a concrete possibility and it is being evaluated," said Francisco Dorignac, president of the Argentine Polo Association, in comments published Tuesday by daily La Nacion.

Argentina is the world's foremost polo-playing country, with some of the best players and best polo horses. The Venezuelan team that lost the horses includes three Argentines: Juan Martin Nero, Guillermo Caset and Martin Espain.

Dorignac was shocked by the events in Wellington. "This is terrible," he said. "We are on alert. We are awaiting the reports to take the relevant measures and precautions."

Experts, breeders and veterinarians in Argentina said the multiple deaths surprised them since the vitamin supplements usually given to polo horses do not have harmful effects.

"The strange thing is that, be they vitamins or whatever, they were given to them before the game, when the normal thing would be to do that afterwards, for recovery," said former polo star Horacio Heguy.

Veterinarian Maximo Aguirre Paz, who specializes in polo horses, warned that "it is not normal that more than 20 horses fall in a sequence.

"It is clear that a toxin has been inadvertently introduced into the horses' systems through a supplement or a vitamin," he noted.

Sources close to the team estimated that the horses were worth 1.5 million dollars.

The team La Lechuza Caracas belongs to Venezuelan multimillionaire Victor Vargas and has been playing annually in the event since 1999. Victor was "in seclusion," according to Peter Rizzo, United States Polo Association executive director.

"This is a very, very traumatic time for him," Rizzo told dpa, the German news agency, Monday.

The investigation is being carried out by the Florida State Department of Agriculture, which is conducting post-mortem examinations and toxicology testing on the remains. Results are expected by week's end, Rizzo said.

Seeking to dampen wild rumours circulating about the cause, Dr Paul Wollenman, a veterinarian who led the effort to rescue the horses as they started to collapse on Sunday, said: "Based on initial, overwhelming clinical evidence this medical event was isolated to the Lechuza barn and horses, and the initial evidence shows no infectious element."

Right before the 3 pm match, as the Lechuza Caracas trainers were preparing their horses, two horses collapsed and several others began exhibiting dizziness and disorientation, according to a statement by the North American Polo League.  (dpa)