David Menuisier's three-year-old had previously finished second in Goodwood Group Three and still appeared to be in with a shout of victory on the Knavesmire before dropping away in the final furlong.
The Pulborough handler expects the Makfi colt to be out of action for at least two weeks, with future targets now up in the air.
He said: "Unfortunately entering the last furlong, I don't know exactly when, he suffered a cut behind his pastern. It is about an inch-long cut and it needed to be stitched.
"The problem with that area is the chance of infection and there is a little bit of an infection there, so he is on antibiotics now.
"It will probably be two or three weeks before he is back in work, so all plans are now on hold.
"It is a shame as he was still travelling well along with the winner and the second, and then he just lost his action in a matter of strides."
Menuisier had more luck in Ireland on Sunday, however, with Sinfonietta bringing home a decent cheque after finishing third in the Irish Cambridgshire at the Curragh.
While the five-year-old is entered in the British version at Newmarket on September 30, Menuisier is circumspect about his chances of running.
He said: "I was delighted with his run. I thought the ground might have got a bit quick for him, but it was OK and he got a good ride from Seamie Heffernan.
"He is entered in the English Cambridgeshire but I am not sure he will get in and the ground might not be quite right for him.
"I might have a look in France, but he doesn't qualify for handicaps there, only conditions races.
"I would like to go back to Ireland with him, but I don't think there's a suitable race for him this year now."