Famed Las Vegas magician Roy Horn, one half of the iconic Siegfried and Roy duo, remains in critical but stable condition after getting mauled by a white tiger during a performance Friday night. "The doctors are encouraged that he will recover," says Horn's spokesman, "but it will be several days until the full extent of his injury is known." Horn, who turned 59 Friday, is on a ventilator and is responding to voice and touch. The prognosis for the Siegfried and Roy show, meanwhile, looks grim. Officially, the long-running spectacle has shut down until Christmas. Unofficially, there's talk the tragedy may force it to close for good.