Aidan O’Brien withdrew all four of his horses from the Prix de l’Arc de Triomphe on Sunday in Paris after they tested positive for a prohibited substance.
It is believed that the prohibited substance was found in contaminated feed.
The Irish coach should drive Mogul, Japan, Serpentine and Sovereign in the richest race in Europe, which Enable wants to win for the third time to a record win.
His sons Joseph and Donnacha also withdrew horses to run in other races at the meeting.
A total of 11 horses trained by the trio are missing.
“Unfortunately, the results of the urine samples from the horses from the French laboratory were positive,” said O’Brien’s Ballydoyle Racing base in a statement.
“There is a chance the pollutant might have left its system by the time of the race on Sunday, but we have no guarantee of that.
“To protect the integrity of racing, we decided to withdraw all of our horses (on Sunday) from racing.
“Joseph and Donnacha O’Brien will too.”
UK trainer Roger Varian, who uses the same feed supplier, withdrew his seven intended runners from meetings on Saturday.
Aidan O’Brien’s runners’ ability to take part in the Paris Longchamp game was questioned on Friday night.
France Galop announced that five horses tested positive for the banned substance zilpaterol, which was believed to be in contaminated animal feed.
The two runners from O’Brien in France on Saturday were allowed to race after urine samples sent to the Irish Equine Center became clear again.
But its contenders for the Arc have yet to be cleared, and the withdrawals will throw a cloud over a highly anticipated game.
Aidan O’Brien’s lead Arc contender, Love, was pulled out earlier this week after heavy rain left the officials very soft.
The absence of his quartet results in Enable, Frankie Dettori’s mountain for British coach John Gosden, facing 10 rivals – the field has been reduced from 15 to 11. She is now the all-time favorite for historic success.
Aidan has also removed St. Mark’s Basilica from the Prix Jean-Luc Lagardere, as horses trained by the O’Brien family have been withdrawn from a total of three other Group 1 races.
Joseph should saddle leading competitor Pretty Gorgeous in the Prix Marcel Boussac, while Fancy Blue will miss the Prix de l’Opera for Donnacha.
