"The horse received immediate veterinary care, however he was unable to be saved due to the nature of the injury sustained.
"Our sympathies are extended to the owners of Anthony Van Dyck, trainer Aidan O'Brien and all his staff who cared for the horse and are greatly saddened by their loss."
Simon Clare tweeted: "Poor Anthony Van Dyck. That was tough to watch."
Greens senator Mehreen Faruqi wrote: "Horrific news ... This is why we say 'nup' to the cup."
It comes after Rostropovich suffered a stress fracture to his pelvis in last year's Melbourne Cup. Fortunately, he made a full recovery.
Anthony Van Dyck is the seventh horse to die on Melbourne Cup day since 2013 and there has been a huge social media push against this year's race, with the hashtag #NupToTheCup quickly trending.
Two years ago the Cup was rocked by the death of Cliffsofmoher — who was euthanised in front of the grandstand crowd after the horse broke its shoulder. Both Cliffsofmoher and Anthony Van Dyck were trained by Aidan O'Brien.
That followed these deaths in Melbourne Cup day races:
In 2013, Verema was euthanised after snapping a bone in her leg.
In 2014, Admire Rakti collapsed and died in his stall after a race and Araldo broke a leg and was euthanised.
In 2015, Red Cadeaux broke his left foreleg, was rushed to the vet for surgery and was euthanised some days later.
In 2016, Regal Monarch died after a dramatic mid-race fall.