The 3-year-old son of Ghostzapper ran seven furlongs in 1:28 2/5 April 22, which was his first work since running fifth in the April 8 Santa Anita Derby (G1).
"He had a good work last week and he didn't come out of it well," Shah said. "The ankle injury would have taken a significant amount of time to recover from ... and it was unlikely he could get back to the level of winning graded stakes, so we decided to retire him."
Prior to the Santa Anita Derby, Iliad ran a far-back second behind Mastery in the March 11 San Felipe Stakes (G2). He broke his maiden by 3 1/2 lengths for Hall of Fame trainer Bob Baffert in December at Los Alamitos Race Course, then—after being moved to trainer Doug O'Neill—won the seven-furlong San Vicente by 3 1/2 lengths Feb. 12 at Santa Anita.
"He certainly had us all dreaming out there for a while, but he was unable to run his best race in the Santa Anita Derby," Shah said of the ridgling, who once had Triple Crown aspirations.
The owner said he plans to make Iliad a stallion, but he has not yet settled on the details.