Why Did 21 Horses Die At A Florida Polo Match?

Why did 21 horses from the same polo team die at a Florida match?Veterinarians are saying that it was probably a toxin that caused this terrible tragedy.They are still working to solve this mystery.Here's more from ABC News:

"At least 21 horses have died after coming down with a mysterious ailment moments before they were scheduled to compete in the prestigious U.S. Open polo tournament.

Though the Florida Department of Agriculture was conducting lab tests to determine the cause of death, veterinarians said they suspected the horses were probably killed by some sort of poison."(END OF EXCERPT)Read the rest here.