The legendary racehorse Black Caviar, who won the hearts of Australians with her unbeaten run of 25 victories, has died the day before her 18th birthday.

Black Caviar’s trainer Peter Moody hailed his famous mare as “a remarkable horse who gave us all the ride of a lifetime and wonderful memories” while the champion’s ownership group 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.

“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.”

In her distinctive salmon pink and black-spotted colours, Black Caviar became a national hero. Australia was bewitched by the story of how trainer Peter Moody, a self-made man from the Queensland outback, had paid just $210,000 for her in 2008 then transformed the hulking injury-prone filly into a champion.

At the peak of her fame, when she equalled the string of 14 straight victories set by the legendary Phar Lap 80 years prior, Black Caviar was hailed globally as the ‘‘fastest horse in the world’’.

Trained by Moody and ridden by jockey Luke Nolen, Black Caviar amassed almost $8 million in prize money. She reigned as the world’s No 1 champion sprinter in four consecutive years from 2010-13 and was inducted into the Australian Racing Hall of Fame in 2013, the same year she retired from racing.

Moody confirmed on Saturday that Black Caviar had been humanely euthanised at the Scone Equine Hospital that morning after giving birth to a foal. “You don’t think it affects you,” Moody told reporters at Caulfield. “But you are being stupid not to think it doesn’t. It’s impossible not to get attached to most animals let alone one like her.

Victoria Racing Club also paid tribute. “Today’s news is a shock to us all,” chair Neil Wilson said in a statement. “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. 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.”