Stier said the injury to The Cliffsofmoher was an unfortunate incident that happened infrequently, as Victoria had one of the best safety records in world racing.
Described as a "tragedy" by veteran Seven commentator Bruce McAvaney, the United Kingdom raider pulled up lame as the field passed the finishing post for the first time.
UPDATE: THERE are reports the horse injured in this year's Melbourne Cup, Cliffsofmoher, has been put down.
"Charlie and myself used to travel to Doncaster and Chester and all of the tracks up north in England, back when I was over there riding, and all of those miles meant this, winning the Melbourne Cup". "Cliffsofmoher was spotted looking very agitated moments before the start and has now been killed after fracturing his right shoulder in the Melbourne Cup".
The race was tinged with sadness however with The Cliffsofmoher breaking down towards the end of the opening straight. "He's really sweating up badly".
But English jockey Ryan Moore had to pull up only 600m into the 3200m journey.
Magic Circle, who finished 17th, was found to have broken a blood vessel, but was recovering well and not in any further danger.
People for the Ethical Treatment of Animals (PETA) has called for an investigation into the death, which it described as "the most recent victim of the cruel annual spectacle known as the Melbourne Cup".
Regal Monarch, trained by Chris Waller, was euthanised after falling in race four previous year, while British stayer Red Cadeaux was put down two weeks after falling and breaking a leg in the 2015 Melbourne Cup.
A year later, pre-race favourite Admire Ratki died after collapsing from heart failure in the stalls minutes after the race.
British-born Araldo shattered his leg after being frightened by spectators; he was also put down in 2014.
Wagering data from last year's Melbourne Cup Day showed that, in the immediate lead-up to the main race, a peak of 850 bets a second were being placed through Sportsbet.
Five other jockeys, including winning jockey Kerrin McEvoy, were also sanctioned for breaching the whip rule. As the remaining 23 horses passed the post, The Cliffsofmoher received medical attention before vets determined it was "unable to be saved".