The Queen is said to have been hit “extremely hard” by the loss of her last corgi, Willow, from a cancer-related illness.
The death of the dog ends Her Majesty’s famous association with the breed, which began when her parents gifted her a corgi, Susan, for her 18th birthday.
Willow, who was almost 15 years old, was a 14th generation descendant of Susan so had a particularly close link to the Queen.
“She has mourned every one of her corgis over the years, but she has been more upset about Willow’s death than any of them,” a Buckingham Palace source told The Daily Mail.
“It is probably because Willow was the last link to her parents and a pastime that goes back to her own childhood.
“It really does feel like the end of an era.”
Willow appeared in a famous 2012 Olympic Games opening ceremony sketch, trotting through Buckingham Palace corridors with the Queen and actor Daniel Craig.
The corgi also featured in the Queen’s 90th birthday official portraits that same year, posing with her and three other dogs on an outdoor staircase at Windsor Castle.
“My corgis are family,” the Queen, 91, has said.
A courtier at the palace was quoted as saying Willow represented “a significant thread running through the Queen’s life”, and “to think the last one has now gone is something of a milestone”.
No world leader has been as widely identified with a particular animal as Elizabeth II with her corgis, said Vanity Fair in 2015.
Whenever her royal schedule allowed, the Queen always fed her corgis herself – reportedly on meat and treats crumbled from her own plate – and walked them daily.
She was still the hands-on carer for Willow until last weekend when the dog’s condition worsened, according to reports.
A vet was said to have been called on Sunday afternoon, when Prince Philip was reunited with the Queen after nearly two weeks in hospital recuperating from a hip operation.
It has been reported that the Queen made the decision to have the dog euthanased because she did not want to prolong the dog’s suffering.
Willow is understood to have been buried in the ground of Windsor Castle, where the Queen has personally overseen a program of breeding Pembroke Welsh corgis since the 1950s.
The Queen has had more than 30 dogs originating from Susan’s puppies Sugar and Honey, who were born in 1949.
The Queen has given away her purebred puppies but never sold one or allowed them to compete at dog shows.
At one point the Queen reportedly had 13 corgis. Former royal butler Paul Burrell, whose duties included mopping up doggy accidents with a soda syphon, claimed he was once knocked unconscious after nine dogs tripped him.
In 2015, the Queen decided to stop breeding the dogs, reportedly because of fears she might trip over them and be hurt.
Also, “She didn’t want to leave any young dog behind” when she dies, longtime friend Monty Roberts – whom the Queen named a corgi after – said in July 2015.
While the royal canine line has died out with Willow, the Queen still does have one last corgi called Whisper, which she adopted after the death of its owner, a former Sandringham gamekeeper.
She also has two dorgis – corgi-dachsund crosses – called Vulcan and Candy.
Buckingham Palace did not comment on the reports of Willow’s death, saying it was a private matter.