Nicky Henderson is not giving up hope of Constitution Hill being able to defend his Unibet Champion Hurdle crown and will have his unbeaten superstar “rescoped” again on Friday, after a below-par workout at Kempton Park on Tuesday put his participation in doubt.

As has become tradition, Henderson took several of his Festival contenders for a spin at the Sunbury circuit, including Constitution Hill, whose only start this season was in the Christmas Hurdle at Kempton on Boxing Day.

Bookmakers were quick to suspend the betting markets in the wake of the work, and the Seven Barrows trainer told the PA news agency his superstar had scoped badly following it.

“Unfortunately, in a routine gallop this morning, Constitution Hill was very disappointing and it transpires, after the vet has scoped him, that there is evidence of mucus,” said Henderson.

“We’re taking a sample of it to a laboratory to analyse it, which will tell us about the significance of it and we should know more after that.

“Last week, he worked brilliantly and he was scoped 10 days ago, but these things happen, just like it did with him earlier in the year (having to miss Cheltenham on Trials day in January).

“Horses are like humans, look how many people had the awful cough around Christmas that took ages to get rid of.”

He went on: “The vets still think it could clear up in a week and all his serious work has been done already, whether he makes it (to Cheltenham) will depend on the severity of it.

“He was disappointing this morning working with Sir Gino (Triumph Hurdle favourite), who he has worked with in the past. He would normally go easily with him, but this morning he couldn’t, so Nico (de Boinville) realised all was not well and wasn’t hard on him.

“Obviously, the mucus was affecting him. He’s not coughing, he’s just got a dirty picture, as we say.

“I’m not saying definitely either way (about Cheltenham) and I’ll keep hoping. As you can imagine, it has come as a bit of a shock.”

Giving an update later on his X (formerly Twitter) account, Henderson said: “Following up on this morning’s situation with Constitution Hill, the sample from his tracheal wash has shown a small increase in the number of neutrophils which indicates a respiratory infection, which is significant but far from drastic.

“He will start a course of antibiotics immediately and we plan to rescope him on Friday in order to monitor which way this is going. He would only be having light exercise this week following this morning’s racecourse gallop.

“Both our own vet and the racecourse veterinary surgeon who scoped him feel we definitely have a chance of correcting this in time and we will be doing everything possible to do so. We have a fortnight to work him and it is possible, so we will keep everybody notified accordingly.

“He is absolutely fine within himself and we have simply got to get on top of this issue as quickly as possible.”

Having been the 1-4 favourite for the Champion Hurdle at the start of the day, by the afternoon Constitution Hill was significantly bigger at 5-4 with the sponsors, who make the Willie Mullins-trained State Man their 4-5 favourite. In their non-runner, money back betting market, Coral make State Man 4-7 and Constitution Hill 4-6.