Marylou Whitney’s Birdstone, winner of the Belmont (gr. I) and Travers Stakes (gr. I) this year, has been retired after a radiograph taken Nov. 2 revealed a medial chip in the colt’s left front long pastern bone (P1).

The son of Grindstone, out of Dear Birdie, by Storm Bird, finished seventh in the Oct. 30 Breeders’ Cup Classic–Powered by Dodge (gr. I), and had been scheduled to race as a 4-year-old with the Whitney Handicap (gr. I) one of his main objectives.

“Soundness was not an issue, but at the level of competition he runs at, we regularly take a survey of radiographs to help us monitor his physical status and well-being and help Nick (trainer Zito) plan for his future training,” veterinarian Joe Migliacci, DVM, said.

“The most recent radiograph that I received (Wednesday) morning by Fed-Ex revealed the fracture