"He had a little filling in his knee yesterday and X-rays showed a piece that broke off," Hough said. "He worked four days ago and came back fine. It seems like something that's been in there and finally broke off."
Hough said Pretty Wild is not in any discomfort, and that surgery likely will be performed at Belmont by Dr. Steven Selway on Sunday or Monday. Following the surgery, the son of Wild Again will need about 90 days to recover.
In six starts this year, Pretty Wild had one victory, two seconds, and two thirds, including second-place finishes in the grade I Hopeful and Futurity Stakes. He broke his maiden at Belmont by 5 lengths on July 13.