The 10-year-old ran a promising race in the King George at Kempton over Christmasbut had been stiff since then, leading to the discovery of his latest injury.
“We were just getting really excited that the old Thistlecrack was still there and hopeful that he would go to the Gold Cup,” said Kim Tizzard, assistant trainer to her father, Colin.
“Gutted for everybody, gutted for the staff and the owners but we have a horse and hopefully he’ll do his box rest and be all right for next season.
“He was a little bit stiff behind after the King George and today he’s been off and had x-rays and bone scans.”
Thistlecrack ran some way below his best when fourth in the Kempton race a fortnight ago but it was an encouraging effort for a horse coming back from a tendon injury and many pundits felt it made him a contender for the Gold Cup in March, for which he was a 12-1 shot.
The news was a blow to his jockey, Tom Scudamore, who said: “He’d come out of Kempton stiff and sore but they [the Tizzards] said no more than usual.
“I was looking forward to going and having a sit on him in the next couple of weeks. It’s just unfortunate.”
Thistlecrack was heralded as the biggest talent in jump racing after winning the King George in 2016, when he was a novice over fences. That was his ninth consecutive success but he has failed to win since, having injured a tendon in defeat by Many Clouds at Cheltenham the following month. By the time of the Gold Cup next year he will be 11, older than any winner of the race since 1969.
This jumps seasons has taken a difficult turn for the Tizzards, who have also had to rule out their popular Cue Card from a planned race this weekend because of a foot infection. Their star novice chaser Finian’s Oscar has been a beaten favourite in his last two starts but there still appears hope that Native River can prove a Gold Cup candidate when he returns to the track next month.