O’Brien said both Hold That Tiger and Ontario are coughing and they are the first two-year-old’s housed at Ballydoyle to go down with the bug.
He has a number of star three-year-old’s, including Hawk Wing and High Chaparral, on the easy-list but his two-year-old’s had escaped until now.
Hold That Tiger was a heavily backed market leader, 6-4 to 11-10, for Sunday’s Group One Independent Waterford Wedgwood Phoenix Stakes at the Curragh, but trailed in last of nine runners behind stable companion, Spartacus. Ontario fared a little better in fifth.
O’Brien had all of his runners on Sunday blood-tested and was last night awaiting the results.
He didn’t have to get the results, however, to know Hold That Tiger and Ontario are in trouble. O’Brien said: “There is no point making plans for any of them just now.’’
Meanwhile a total of 10 horses, headed by Henry Cecil’s High Pitched, have been left in Saturday’s Group Two Stan James Geoffrey Freer Stakes at Newbury.
The four-year-old was rerouted from a Group One race in Germany on Sunday in favour of a tilt at this mile and five furlong event.
His rivals are headed by the progressive Mubtaker from the Marcus Tregoning yard who ran a neck second to Millenary in the Princess Of Wales’s Stakes at Newmarket last time out.
Also among the confirmations were the James Fanshawe-trained pair of Arctic Owl and Travelmate and Luca Cumani’s Boreas.
Daliapour is set to be Sir Michael Stoute’s only representative while Murghem could run for the in-form Mark Johnston yard.
Amanda Perrett has Maniatis among the acceptors along with Clive Brittain’s Warrsan, while a surprise possible is Persian Punch.
David Elsworth’s nine-year-old disappointed badly last time in the Goodwood Cup when finishing last, some 25 lengths behind winner Jardine’s Lookout.
Nicky Henderson could be double-handed in next Wednesday’s Tote Ebor with both Cupboard Lover and Dancing Bay on course for the York event.
Cupboard Lover is a 14-1 shot for the mile and six furlong contest with William Hill, while Dancing Bay is available at 20-1 with the same firm.
And Henderson confirmed yesterday: ‘‘Both are in good form and on course for the race.’’
Both horses have shown the best of their form on ground that was good to soft at best and the Lambourn trainer admits both will need conditions on the Knavesmire in their favour if they are to run.
He explained: ‘‘Cupboard Lover just needs to get his toe in a teeny bit but he can run on good ground.
‘‘Dancing Bay would need soft ground and that would be the proviso.
‘‘The plan is to run them both but the ground will dictate, Cupboard Lover only needs it good but Dancing Bay would really need it good to soft.’’
Dancing Bay was allotted 8st 4lb in the original handicap while Cupboard Lover was given 8st 2lb for the £185,000 event and Henderson added: ‘‘Both of them look like getting in though as they’re right next door to each other.’’
The six-year-old Cupboard Lover will be looking for his fourth win in a row on the Flat after a so far successful season.
He spent the winter hurdling but turned in a fair performance on the level when second behind Royal Mirage at Windsor in June.
The son of Risk Me followed that up with two wins at Newbury and a win last time out over two miles at Sandown.
Weatherbys have announced plans to launch The Stallion Book on the Internet.
Although the book will continue to be printed in its traditional format and sent free of charge to every breeder with two or more broodmares, stallion owners can now reach mare owners around the world.
Stallion owners will be able to take advantage of a two-page colour entry and an additional on-line slot including the option of video footage and a direct link to the entrant’s own internet site.
Weatherbys plan to update the site every two weeks with new progeny performance records.