Trainer Ralph Beckett plans to give Moonstone Magic a break after she scoped badly following her disappointing run in Sunday's 1000 Guineas.
The three-year-old impressed on her debut at Leicester in mid-April and followed up in brilliant style in the Fred Darling Stakes at Newbury.
She aimed for a quickfire hat-trick in Sunday's Classic at Newmarket, but trailed home a well-beaten 15th of the 17 runners.
Although an initial scope suggested Moonstone Magic was fine, subsequent tests on Monday revealed the filly was under the weather.
Beckett said: "It's rather strange as she scoped clean immediately after the race, but then we did a trachea wash on her on Monday and while it again looked clean, the bacteriology results said it was dirty.
"We'll give her a break now and bring her back later in the year."
