An obstruction to the small intestine was discovered late on Wednesday after vets were called in to examine the dual- classic winner. Balanchine had begun to show signs of colic, a problem that can kill. The vets carried out an emergency operation that night.
Yesterday, Simon Crisford, speaking for the filly's owners, the Godolphin Management Company, thanked the veterinary team, including Huw Neal and Andrew Edgar of Greenwood, Ellis and Partners, for the speed at which worked. 'They did a fantastic job,' Crisford said.
'Balanchine is receiving intensive post-operative treatment. Her progress so far is satisfactory. We are constantly monitoring the situation and are hopeful of a favourable outcome.' he added.
The next few days are crucial to her recovery, but yesterday it seemed unlikely she would run again this season.
The filly spent her two- year-old days with Peter Chapple-Hyam, who trained her to two successes before she was sold by Robert Sangster to Godolphin.
She was sent to spend the winter in Dubai in the care of Hilal Ibrahim. A Classic campaign was mapped out for Balanchine and she returned to this country to be stabled at Newmarket, with John Gosden's assistant, Jeremy Noseda, overseeing her routine.
After finishing a short- head second to Las Meninas in the 1,000 Guineas, the filly took the Oaks in style. Then, three weeks ago, Balanchine put on a superb display to defeat the colts in the Irish Derby. She came home four and a half lengths ahead of the Epsom Derby runner-up King's Theatre, with Epsom third Colonel Collins again filling the minor placing.
Her owners had mapped out a campaign which would have reached a climax with a run in the Prix de l'Arc de Triomphe at Longchamp in October. But her illness will almost certainly rule out those plans.
Colonel Collins, one of Balanchine's victims at The Curragh, ran poorly in the Group Two Prix Eugene Adam at Saint-Cloud yesterday. The even-money favourite could finish only sixth.
Three days ago, it was announced that Robert Sangster had sold a majority share in Colonel Collins to Gary Tanaka, an American businessman. Yesterday's run was the colt's final appearance in Europe before a career in the United States.
The son of El Gran Senor held every chance two furlongs out but was soon beaten once John Reid asked him for an effort. Carnegie, the 8-5 second favourite trained by Andre Fabre, took up the running a furlong out to win by half a length from Cafe Milano.
Chapple-Hyam, the trainer of Colonel Collins, said later: 'He hasn't run his race. He was in a perfect position at the turn. The race was run to suit him and I cannot explain it. He will still go to America and will probably run in the Secretariat Stakes.'