Lovethehigherlaw, winner of the Grade 1, Punchestown Champion Bumper in May, suffered a fatal injury on Saturday morning.
The five-year-old gelding, who was set to embark upon a potentially exciting hurdling campaign this winter, died at trainer Willie Mullins' yard.
Eddie O'Leary, racing manager for owners Gigginstown House Stud, said on Sunday: "It happened yesterday morning at Willie's when the horse was heading to the gallops.
"It's a great loss as he had such a bright future."
