Speaking with NME about his hoofed "Lord of the Rings" souvenirs, Mortensen revealed that one of them had in fact stood in for Brego during filming. "There were actually three horses that I bought, they were up for sale once the movies were done," he explained. "There were the two I'd ridden — a chestnut and then the big bay that Aragorn rides."
But he decided not to keep the third horse, which stood in for Arwen's Asfaloth in the movies. According to Mortensen, he gave that particular horse to the woman who served as stunt double for Arwen in the memorable scene in which Arwen escapes from the Black Riders with Frodo. Mortensen added that he became friends with the stunt double, explaining, "I knew how much she liked that horse, so I bought it for her."
While both of Mortensen's horses have since passed away, he revealed that the one who played Asfaloth is still alive and kicking. That's welcome news for anyone who rightfully thought Asfaloth was an MVP of the trilogy.