A low-grade infection has been running through Ballydoyle runners for over two months, trainer Aidan O'Brien revealed on Sunday. O'Brien voiced his concern after a number of below-par performances at the Irish Champions Festival and at Doncaster during the St Leger meeting for his string.“There is a low-grade infection running through our horses for the last two months, [maybe] a little bit more,” said O'Brien. “It would pop up in their bloods and an odd one would have a funny scope and then it would disappear without being treated.“It was with them all, through the whole place. We blood them and scope them and if all that is right, and everyone is happy, we let them run. But sometimes you don't know until they travel.”In the G1 St Leger won by Highwayman (Persian King), G1 Derby hero Christmas Day (Camelot) ran ninth, while Pierre Bonnard (Camelot) was sixth.Said O'Brien, “Ronan [Whelan] said he [Christmas Day] coughed going to the start. He just said he ran out of gas going to the furlong marker.“Horses do those things a lot of the time at home. It's like yourself when you get up in the morning, you could have a phlegmy throat and give a few coughs and that's it. What do you do? Stay in bed if you have a flu or a cold?“You ask an athlete do you not run, or not race, if you have a flu or feel a bit chesty. It's just not the way the world is. It's there and they are working through it and it will disappear.“I only said it because Ronan brought it to the fore yesterday and the horse ran the way he did. It was just to make everyone aware of it. It's not a big issue.”Below par performances were not limited to the U.K., with multiple Group 1 scorer Constitution River (Wootton Bassett) third in the G1 Irish Champion Stakes and Florida Bay (Mehmas) filling that same position in Sunday's G1 Goffs Vincent O'Brien National Stakes.“You are never sure anyway, especially with three-year-olds come this time of year after being training for the Classics,” said O'Brien. “It's hard for them to keep turning up and sometimes they will disappoint.“I wouldn't take away from any horse that has run against us in the last couple of months ever, because I know how difficult it all is. But he [Constitution River] did an unusual thing – he travelled through the race like a dream and he went there and hit a wall half-a-furlong down.”O'Brien said Constitution River is set to undergo a course of antibiotics but could still be seen again either over a mile in the G1 Queen Elizabeth II Stakes or the G1 Champion Stakes over a mile and a quarter, both on Champions Day at Ascot on October 17.“Obviously we backed him up a little bit quick after York after having a tough race and he might have felt it a little bit, but don't take away from the first or second in any way. I'm just saying that's what would be going on in my mind,” he said.“He'll probably have a week's antibiotics as a cover thing and have an easy couple of weeks. Then we'll see whether he will go to Ascot for either the mile or the mile-and-a-quarter. It is possible that he'll really bloom again.“It was unusual what he did yesterday, the way he went through the race, but that's the way it is and we're used to it all the time. We'll keep tweaking things and hopefully get him back.”The post ‘Low-Grade Infection’ Disrupting Ballydoyle Runners appeared first on TDN | Thoroughbred Daily News | Horse Racing News, Results and Video | Thoroughbred Breeding and Auctions.