The Australian horse racing community mourned the death of championship thoroughbred Black Caviar on Sunday, who died on the eve of her 18th birthday.

The horse died on Saturday, one day before its 18th birthday, the group of its owners said.

Black Caviar remained undefeated in all 25 races she entered before her retirement in 2013 and is widely regarded as one of the best sprinters horse racing has ever seen.

“Today’s news comes as a shock to us all. Black Caviar was more than a champion racehorse, she was an important part of many people’s lives,” Neil Wilson, chairman of the Victoria Racing Club, said in a statement on Saturday. “She was simply the best.”

One of Black Caviar’s most famous victories was in England at Royal Ascot, where she won the Diamond Jubilee Stakes in 2012 in a dramatic finish.

“She was a remarkable horse who gave us all the ride of a lifetime and wonderful memories,” said her trainer Peter Moody.

Black Caviar was suffering from an illness, Moody told Racing.com. The horse was euthanized after giving birth at the Scone Equine Clinic near Newcastle.

“She had lost circulation in her front legs. Unfortunately, the only humane thing to do was to euthanize her, which was very sad,” Moody added.

Jockey Luke Nolan, who rode Black Caviar to most of her victories, said he felt lucky to have been “part of her wonderful career”.

“Most drivers would give their right arm to have the chance to be part of this chapter of racing history like I did,” Nolan told Fox Sports.

“It’s a bit of a hollow feeling, a blurry image, because she meant a lot to us.”

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