An infection persisting for over two months causes concern for Aidan O’Brien at Ballydoyle

The master trainer revealed that a low-grade infection has been lingering across a significant portion of his powerful string, attributing several below-par performances to the bug. Christmas Day and Constitution River were among the latest horses impacted by the outbreak

COUNTY KILDARE, Ireland (Special for Turf Diario).— Behind a string of unexpected setbacks for Ballydoyle in recent weeks lies an explanation that Aidan O’Brien has only now chosen to reveal. A low-grade infection has been circulating for over two months among the horses at the powerhouse Irish yard, evolving into a growing concern that is forcing the team to exercise extreme caution.

The master trainer addressed the situation following a weekend in which several of his marquee runners underperformed significantly. The most glaring instance was Christmas Day (Camelot), winner of the Derby (G1), who faded badly to finish ninth in the St Leger (G1) at Doncaster. Likewise, Pierre Bonnard (Camelot) failed to produce his best form, managing only sixth behind Highwayman (Persian King).

Hours later at Leopardstown, Constitution River (Wootton Bassett) travelled like a winner in the Irish Champion Stakes (G1), only to empty abruptly in the closing stages, finishing third—beaten 3/4 of a length by Hotazhell (Too Darn Hot) and Wimbledon Hawkeye (Kameko).

It was then that O’Brien laid bare the ongoing struggle Ballydoyle has been managing behind closed doors. “There’s been a low-grade bug among our horses for the last two months, maybe a bit longer. It shows up in blood tests, or sometimes on a scope, and then it clears up without needing treatment,” he explained.

According to the trainer, the issue has touched virtually the entire stable, though its intermittent nature makes it exceptionally difficult to determine when a runner is truly compromised.

“It’s everywhere, all over the yard. We scope them, test their blood, and if everything comes back clean and we’re happy, we let them run. But sometimes you just don’t know until they actually travel,” he added.

The disappointment with Christmas Day was the tipping point that brought the issue to light. Jockey Ronan Whelanreported to O’Brien that the son of Camelot had coughed on the way to the starting gates and simply ran out of petrol with 200 meters left to run.

The trainer downplayed the severity of the illness, comparing it to minor respiratory discomforts humans often experience without needing to stop their daily routines completely.

“It’s not a major issue,” he clarified, while conceding that it suffices to explain why a world-class horse might suddenly fail to deliver expected performance.

O’Brien was also quick to emphasize that he was not using the bug to diminish the achievements of rivals who have bested his runners recently.

“I wouldn’t take anything away from any horse that has beaten us over the last two months, because I know how difficult this game is,” he stressed.

The case of Constitution River differs slightly from Christmas Day, though it equally raised red flags.

The Eclipse Stakes (G1) victor was coming off a demanding effort at York before making a relatively quick turnaround at Leopardstown. For most of the Irish Champion, he travelled with supreme ease, yet failed to sustain his surge when asked for the ultimate effort. “He travelled like a dream during the race, got right there, and then hit a wall with 100 meters to go. It was very unusual for him,” O’Brien explained.

The plan now is to administer a one-week course of antibiotics—more as a precautionary measure than a response to a severe condition—before significantly easing back on his workload for a fortnight.

Should his recovery prove satisfactory, Constitution River could still return on October 17 for Champions Day at Ascot, with two options under consideration: dropping back to the mile for the Queen Elizabeth II Stakes (G1) or remaining at 2000 meters in the Champion Stakes (G1). “He might blossom again. We’ll keep tweaking things and hopefully get him back on track,” O’Brien noted.

This complication arrives at a delicate juncture in the season, just as Ballydoyle’s premier horses prepare for their final autumn targets. The trainer himself acknowledged that three-year-olds naturally find it tough to maintain peak form after months of intense conditioning through the gruelling Classics campaign.

While Ballydoyle continues to capture major races through sheer stable depth, the hidden struggle inside the yard is now out in the open. O’Brien maintains it is not a crisis and refuses to offer it as an excuse. Nevertheless, with Champions Day and the year-end international fixtures looming, eradicating the persistent bug has become the most critical race on the Irish team's calendar.