The operators of the Golden Gate Fields racetrack near San Francisco, Calif., are investigating how a retired Thoroughbred racehorse wound up for sale at a livestock auction.

Golden Gate Fields General Manager Joe Morris said that a 2-year-old Thoroughbred named New Macho Man retired from racing after sustaining a leg injury. Golden Gate Fields has a policy banning the sale of its retired racing horse at auction, he said. The ban is intended to prevent horses from being bought by so-called “kill buyers” who sell horses for slaughter in Mexico and Canada.

Following his retirement, the New Macho Man’s trainer gave the horse to a friend with the stipulation that the animal was only to be used for riding, Morris said.

“It’s hard to know what happens (if) somewhere down the line the horse goes to someone else and then to someone else after that,” said Morris