Nassalam will miss the chance to defend his crown at the 2024 Welsh Grand National at Chepstow Racecourse.
The seven-year-old, trained by father and son duo Gary and Josh Moore, cruised to a 34-length win in last year’s race.
Trainer Josh Moore told At The Races: “He’s missed some key bits of work at home, he just needs a bit of time and this has come too soon.”
Eight-year-old Monbeg Genius is the current bookmakers’ favourite for this year’s race, which is scheduled for Friday, 27 December.