Constitution Hill won't be racing at the Cheltenham Festival, his trainer Nicky Henderson has said.
The star horse, who hasn't lost a race and won the Champion Hurdle last year, didn't do well in a practice run at Kempton Park last week.
He was found to have a bit of mucus in his lungs when they checked him and, even though he seemed a bit better after that, a blood test on Thursday brought more bad news.
They checked him again on Friday morning, and Nicky Henderson shared that "showed the Neutrophil percentage, indicative of infection, was back to normal parameters with no mucus evident".
But he said another blood test on Monday would be really important. After getting those results, he wrote on his official X account: "Very sadly we are going to have to admit defeat in the battle to get Constitution Hill ready for the Champion Hurdle and therefore have to declare that he will not be running there this year."
Henderson added: "He has undoubtedly improved over the weekend and seems noticeably brighter than he was at the end of last week and I really did think he was much perkier when ridden this morning.
"Unfortunately the all-important blood test shows that although the figures have also improved, they are quite a way from being satisfactory for a horse to commence serious training and to race in a week's time.
"There are three significant markers on the blood test all of which have come down since Thursday's sample but are still raised enough to indicate that he has not fully recovered from whatever was ailing him.
"The only way to continue the improvement is not to stress him and he obviously cannot run in these Olympic games if he's not trained sufficiently.
"This is very sad for all of us and particularly
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