Snow Fairy has been ruled out of the Prix de l'Arc de Triomphe and the rest of the season after being found to have heat in a tendon.
An injury sustained at the end of last year threatened to bring the five-year-old's racing career to an end but she roared back better than ever.
Following a comeback victory in the Prix Jean Romanet at Deauville, Snow Fairy registered her seventh Group One haul and broke the Leopardstown track record when winning the Irish Champion Stakes.
Connections had been looking forward to a second trip to Paris on Sunday week after she finished third in last season's Arc, but she was found to be suffering from heat in a tendon after working on Friday.
"She worked yesterday and we were very pleased with her, but last night we found just a little bit of heat in the leg," Dunlop said.
"Taking everything into consideration with the previous injury she's had, it was too much of a risk to carry on, so we've pulled stumps."
The Newmarket trainer did, however, leave open the possibility his pride and joy could return to the racecourse next year if she fully recovers.
"(Owner) Mrs Patino is keen if possible to think about next season, but she will not be running again this year," said Dunlop.