Royal Ascot winner Namibian remains in intensive care after having undergoing surgery for colic that has ended his season.
Trainer Mark Johnston said the three-year-old colt is "back on his feet" but the setback has ended plans to run him in the St Leger at Doncaster.
"Namibian was found to be showing signs of colic on Friday morning and our vet John Martin attended and treated him.
"When he was not responding to the initial treatment, a decision was made to transfer him to the Newmarket Equine Hospital and, on arrival there, they decided to operate.
"He is back on his feet but he has undergone major abdominal surgery and part of his bowel has been bypassed.
"He will remain under intensive care for a few days, at least, and we must now hope that there are no complications. Whatever happens, he will not be racing again this year."
Namibian had looked a decent prospect for the world's oldest classic at Doncaster on September 10 after winning the Queen's Vase at Royal Ascot and the Gordon Stakes at Glorious Goodwood.
However, he disappointed in the Great Voltigeur Stakes at York when only fifth of six behind Sea Moon.
