Dettori, who had been due to ride in the Prix de l'Arc de Triomphe on Sunday, was unseated from his horse Eland Ally on the way to the start of a race in Nottingham.
"Sunday is out - as is the season," Dettori's spokesman Peter Burrell told the BBC.
One of the biggest names in the sport, Britain-based Italian Dettori ended a six-month ban for doping in May.
The blow means Dettori, who will turn 43 at the end of the year, will be unable to contest what would have been his 26th successive Prix de l'Arc at Longchamp.
He was due to ride Treve after having been paired up with the French thoroughbred for the first time at the Prix Vermeille last month.
Together they comfortably won the Prix de l'Arc preliminary with the combination of the Italian's experience and the three-year-old filly's youth attracting attention in the racing world.
That win confirmed Treve's status as co-favourite for Sunday's race, along with Orfevre and Novelist, but also gave belief to Dettori that he could add a fourth win at Longchamp.
The only non-French jockey to win the Prix de l'Arc four times is Pat Eddery.
With Dettori now out of the frame, Olivier Peslier - looking to become the only jockey to win it five times - and Johnny Murtagh - born in the same year at him, in 1970 - could steal a march.