The Melbourne Cup has been marred by the death of a second horse as Araldo was put down after breaking a bone in its leg.
As German-trained Protectionist romped away to a four-length victory a stricken Admire Rakti, the pre-race favourite, trailed in a long last. Minutes later the seven-year-old from Japan collapsed and died in his stall.
Seventh-placed Araldo was spooked on the way back to his barn and kicked at a fence breaking the pastern bone in its hind leg and was eventually put down by vets.
In a statement, Racing Victoria's head of veterinary and equine welfare Dr Brian Stewart expressed his sympathies to Admire Rakti's owner and trainer.
"A post-mortem will be conducted at the University of Melbourne Veterinary Hospital as is standard practice.
Rights groups speak out
Australia's RSPCA released a statement on Tuesday afternoon saying the tragic events were a "stark reminder" of the damage the sport can have on horses.
"Sadly, injury and death are the price some horses pay for our entertainment in a sport that puts intense pressure on animals to perform to the limits of their endurance," the statement read.
The Coalition for the Protection of Racehorses (CPR) followed said the incidents were anything but rare occurrences in the world of horse racing.
"This is a sport that has been doing what it wanted to do for the last 200 years, and now it's starting to realise that it needs to make some changes," CPR campaign director Elio Celotto said.
Mr Celotto told Radio New Zealand's Nine to Noon programme he had information, as yet unconfirmed, that Admire Rakti suffered a heart attack, which is what happens when horses are pushed beyond their limits.
CPR claims 125 horses died on race tracks in Australia in the year to July.
New Zealand Racing company secretary Simon Cooper told the programme only four horses had died in this country over the same period and the industry was doing its best to limit fatalities.
He said the New Zealand Racing Board invests $300,000 annually in research into the welfare of race horses among other things.
Big winning margin
Protectionist, who will remain in Australia, was the third favourite for the gruelling 3200m race and was further back in the field than planned, AAP reports.
Ryan Moore, who won the Cox Plate on Irish horse Adelaide, steered Protectionist between the gaps and once in clear air, the horse streeted away.
It was the biggest winning margin in nearly two decades since Doriemus also scored by four lengths in 1995.