Constitution Hill will not run at the Cheltenham Festival, trainer Nicky Henderson has announced.

The unbeaten and defending Champion Hurdle hero worked poorly at Kempton Park last Tuesday, putting his participation at the showpiece meeting in major doubt.

A scope showed mucus in his lungs and despite slightly more positive news in the following days, results of a blood test on Thursday proved to be another blow.

He was scoped again on Friday morning, with Henderson saying that “showed the neutrophil percentage, indicative of infection, was back to normal parameters with no mucus evident”.

However, he stressed another blood test on Monday would probably prove to be the “acid test”, and on receiving the results he posted 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.

“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 Michael (Buckley, owner) but it is in everybody’s best interests that we ensure we have a fit and healthy Constitution Hill to win back his crown next year.”

State Man, who finished second at Cheltenham last year, is now the 1-3 favourite for the Champion Hurdle with Coral, while Paddy Power offer odds of 2-5.

Constitution Hill could yet run again this term, with Aintree and Punchestown possible options according to Buckley, although future plans are on an immediate hold, pending the gelding’s return to better health.

He told the Nick Luck Daily podcast: “I think that’s what we’d like to think of doing (going to Aintree and/or Punchestown next). I think we will wait for 10 days and just make sure.

“There’s no point in talking about it to anybody now simply because we just want to make sure he does get rid of all these infections and he seems to be fine and perky and so-forth, and then we might think about one or the other.

“I doubt that we would run in both to be truthful, but who knows.”