Legendary Australian racehorse Black Caviar has died not long after giving birth.

The beloved mare had been battling an illness for some days and connections made the heartbreaking decision to put her down on Saturday morning following the birth of the colt foal.

Peter Moody, the trainer who steered Black Caviar to a stunning record that boasted a perfect 25 wins from 25 races, said it was the “only humane thing to do”.

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“I’ve known she’s been a little bit ill for a few days,” Moody said on RSN. “We were hoping and hoping. But she fought a good fight like she always did each and every time she stepped out onto a racetrack.”

He said Black Caviar — who would have celebrated her 18th birthday tomorrow (Sunday, August 18) — had suffered some feet problems and was not going to be able to live with the issues.

After her debut in 2008-09, Moody, jockey Luke Nolen, and Black Caviar took the racing industry by storm, with the horse going on to amass almost $8 million in prize money.

In 2013 she was the No.1 ranked horse in the World Thoroughbred Rankings and she was also the world’s No.1 champion sprinter in four consecutive years from 2010-13.

She retired from racing in 2013.

Moody said Black Caviar was a “remarkable horse who gave us all the ride of a life time and wonderful memories”.

A statement from Black Caviar’s ownership group confirmed the sad new.

“It is with deep sadness that the Madden, Hawkes, Wilkie, Taylor and Werrett families wish to advise that champion mare Black Caviar passed away peacefully today,” the statement said.

“Black Caviar was a once-in-a-lifetime horse, most famous for her stellar racing career which saw her undefeated with 25 wins from 25 starts.

“Since racing retirement, Black Caviar has continued her successes as a broodmare, with her legacy to continue through her sons and daughters.

“The ownership group are devastated, however will reflect on her glittering achievements not only in Australia where she transcended racing and captured the hearts of the public, but in England where she famously won the 2012 Group 1 Diamond Jubilee Stakes (1200m) at Royal Ascot.”

Victoria Racing Club (VRC) chairman Neil Wilson also extended his condolences.

“Today’s news is a shock to us all. Black Caviar was more than a champion racehorse, she was an important part of life for many people. Her brilliance, her presence and the pleasure and inspiration she gave to so many was a special moment in time for horse racing and sport more generally,” Wilson said.

“She has created a piece of history that will be remembered forever, and it was a privilege for all who saw this wonderful equine athlete in action.

“The VRC was privileged to have Black Caviar race at Flemington and to have the Lightning Stakes named after her in 2013, a race she won three times including the first year it was named in her honour.

“Our heartfelt condolences go out to those close to her, including our friends in the ownership group. To Black Caviar’s trainer Peter Moody and jockey Luke Nolen, our thoughts are with you on this sad day.

“She was simply the best.”

The ownership group thanked the public for their support and has requested privacy.