The Kris Lees-trained German stayer, Salon Soldier, unbeaten in two Australian starts, died suddenly on Wednesday morning.
As reported in the Herald Sun, the horse had been in light work in Newcastle when he fell ill on Tuesday, showing signs of colic.
The four-year-old's condition worsened overnight and he died this morning.
Salon Soldier won the Listed Victoria Plate at Flemington on Melbourne Cup Day and the Myer Spring Fashion Handicap at Randwick on his Australian debut.
Sky Sports Radio personality Jimmy Smith tweeted "@Jimmy_Smith25: Devastated to learn of the passing of the mighty #SalonSoldier what a ride it was! Thoughts with @Leesracing @Austbloodstock @JoelCaine"
Salon Soldier was being set for the major autumn staying races, including the Group 1 BMW on April 5 and the Queen Elizabeth Stakes on April 19.
Salon Soldier finished his career with 3 wins, 7 places from 13 starts and earned over $130,000 in prizemoney.