Nicky Henderson admitted the results of a blood test on Constitution Hill were “probably not what we were hoping for” as the horse faces a race against time to be fit for the Unibet Champion Hurdle.

The reigning two-mile champion had been very skinny odds for a Festival defence until he posted a lacklustre workout at Kempton on Tuesday morning, when the seven-year-old was virtually pulled up by Nico de Boinville.

It transpired after he was scoped that he had mucus in his lungs but Henderson had been able to issue an upbeat bulletin on both Wednesday afternoon and Thursday morning.

However, the Seven Barrows handler was then less encouraged when later getting the results of a blood test on Constitution Hill, and the unbeaten runner will repeat the process on Monday in the hope of an improvement.

In an update posted on X (formerly Twitter), Henderson said: “The result of the blood test taken this morning goes quite a long way to explaining his disappointing performance at Kempton on Tuesday and confirms that he has a significant degree of inflammation.

“The figures themselves suggest he is definitely under the weather and we will need to repeat the test again on Monday in the hope that the situation improves.

“We intend to scope him again tomorrow morning, but it appears that the blood test is a more conclusive barometer and the one we need to concentrate on.

“This is probably not what we were hoping for, but at least it tells us exactly where we are.”

Henderson had described his superstar as “alert and bright” earlier on Thursday as he walks a line between giving the Michael Buckley-owned gelding adequate recovery time, while trying not to lose too much of his fitness edge.

“He can’t stay in his box, if we’ve got any pretentions of running in the Champion Hurdle, you can’t just knock it off and tuck him in bed,” Henderson told Sky Sports Racing.

“We’ve got to find the right balance between keeping him moving but not stressing him in any way at all. He is the most relaxed person you’ll ever come across and I actually think he looks quite bright.

“Horses often get these problems, they are like kids in school. He hasn’t coughed at all. It’s exactly like a school, you can’t have 100 per cent of them right all of the time, it’s not possible. Normally we’d have time to get over it, it’s the timing that is wrong.

“If he was a normal horse you’d leave off him for a week and aim at something else but while there is something else to aim at, there’s only one Champion Hurdle.

“Work-wise he’s done all his galloping, we’d do another piece of work next week to see where he is if everything is testing good. That would have to be him at his best.”