Trainer Aidan O'Brien was upset when notified about the death of The Cliffsofmoher in Tuesday's Melbourne Cup at Flemington, according to stable foreman TJ Comerford.
The five-year-old was having his 18th start when he fractured a shoulder coming out of the straight for the first time and had to put down, leaving stable staff shattered.
O'Brien heard the news as he took his annual week's break after the Breeders Cup meeting in America, with his son Joseph on hand at Flemington to watch the race.
Comerford told Fairfax Media on Wednesday that there was no inkling whatsoever that such an accident would occur.
"We see it now and again. It's not good but these things happen," Comerford said.
The death partly overshadowed the first Melbourne Cup win by Godolphin on Wednesday morning with many people concerned about the death of a fifth horse in a Melbourne Cup-related incident in the past six years.
Nick Williams, who part-owns The Cliffsofmoher, texted radio station SEN a message that was read out on air.
"Horse welfare comes first ... I can assure you that nobody could be more upset it about it than us," Williams wrote.
Racing Victoria stewards referred the incident to the Equine Welfare Department and an inquiry will be held into the incident with a report not expected for a few weeks.
Racing Victoria will collect the horse's medical records and obtain The Cliffsofmoher's exercise records in consultation with the stable.
Racing Victoria's head of integrity Jamie Stier told SEN on Wednesday that all fatalities are reviewed to determine whether there were any identifiable risk factors that could minimise the chances of a racehorse dying in the future.
Vets were on hand at Werribee to inspect several other international horses from the race with Comerford telling Fairfax Media Yucatan, who stewards reported as lame in the near foreleg, had been out for a walk and would recover well.
He said Rostropovich, who finished fifth in the race - lending further weight to the argument that northern hemisphere three-year-olds are at an advantage - will return home for a break.
The Coolmore stable has several sprinters running on Saturday including US Navy Flag and Spirit of Valour with Comerford saying he expected the stable to have another tilt at the Cup next year.
"We're not finished yet. We'll be back again," Comerford said.
Vets also inspected Marmelo and Nakeeta with the second-placed Marmelo in good order after the run according to stable foreman Tommy Berry.
"That will be him done for the year," Berry told Fairfax Media.
Nakeeta's connections were pleased the horse secured prizemoney by running 12th after a fifth place in the race in 2017 and the horse will return to Scotland for a break.
Third placegetter A Prince of Arran trotted up well after the race on Wednesday morning, having run in two staying races in four days.