Irish St Leger Victory Amid Infection Concerns at Ballydoyle

By the Editorial Team · Monday, September 14, 2026

Scandinavia won the Irish St Leger for trainer Aidan O’Brien despite a low-grade infection affecting several horses in his stable at Ballydoyle. This victory, along with multiple Group 1 wins that weekend, highlights the stable's resilience while the infection is managed with ongoing treatment and future race plans remain uncertain.

Scandinavia secured a fifth Group 1 victory on Saturday despite challenges posed by a mysterious infection affecting horses at Ballydoyle, trainer Aidan O’Brien revealed. The four-year-old colt, ridden by Ryan Moore, triumphed in the Irish St Leger at the Curragh, overcoming softer ground conditions and a stable-wide health concern that has impacted O’Brien’s string in recent weeks.

O’Brien disclosed that his yard has been battling what he described as a “very low-grade infection” for the past couple of months. Although the precise cause remains unidentified, the illness has been intermittently detected through blood tests and scopes. The trainer noted that horses are always tested before races but that symptoms can sometimes emerge during travel. Despite treatment with antibiotics, O’Brien acknowledged some horses had underperformed recently, including Derby winner Christos Day, who displayed signs of illness in the St Leger at Doncaster on Saturday.

“Every now and then it pops up in their bloods and scopes, but we can’t put our finger on where it is or what it is,” O’Brien said. “We’ve given them antibiotics and they should be running more consistently in a month or so.” Still, he expressed satisfaction with the weekend’s overall results, highlighting two wins at the Curragh amid tough competition.

Scandinavia outpaced stablemates Queenstown and Jan Brueghel in the Irish St Leger, starting as the 4-11 favorite. O’Brien praised Scandinavia’s stamina and galloping ability, stating the horse maintains a “high cruising speed” and has “an unbelievable amount of stamina.” Looking ahead, he indicated that Scandinavia might be rested for the remainder of the season, with decisions on future plans pending.

Earlier on the same card, O’Brien celebrated his 12th victory in the Moyglare Stud Stakes as Sun Goddess dominated the race. The filly won by six and a half lengths, leading to odds shortening for the next year’s 1,000 Guineas, where she is now favored at 3-1. O’Brien described her as “a big, strong, powerful filly” who adapts well to soft ground and showed no signs of exertion after racing.

O’Brien also secured wins in the other Group 1 contests that day. Comanche Brave, ridden by Donnacha O’Brien, claimed the Flying Five, while Folsom Blues, partnered with Joseph O’Brien, won decisively in the National Stakes.

The weekend’s successes came amid the ongoing health concerns at Ballydoyle but demonstrated the resilience of O’Brien’s stable despite recent setbacks.

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