Vulcan, a dachshund-corgi cross belonging to Her Maj, passed away of "old age" at Windsor Castle, leaving Queen Elizabeth II "upset" over the passing of her long time companion.
The tragic news means the Queen is now left with just one dog after she gave up her hobby of dog breeding in 2018, because she did not want to leave any pets behind were she to die.
It means Dorgi Candy is Her Maj's last remaining pet.
Vulcan is said to have passed away at Windsor Castle surrounded by loved ones, and his also said to have been buried at the royal residence.
Sources claimed that aides also feared her pooches, who followed her around and have been photographed more than some royals, would trip her up as they stuck to her heels.
The news comes weeks after Prince William, Kate Middleton and their children Prince George, Princess Charlotte and Prince Louis experienced the heartbreak of their beloved pet dog Lupo dying.
The Duke and Duchess of Cambridge announced on November 22 that their beloved pooch had passed away the previous weekend.
William and Kate said Lupo had been "at the heart" of their family and was even responsible for picking Prince George's name.
A palace source told the Sun: "Clearly the loss of a loved pet is upsetting."
The Queen's dogs starred in the 2012 Olympics opening ceremony, as Daniel Craig's James Bond accompanied the Queen from the palace to a helicopter, with the dogs leading the way.
Vulcan and Candy also featured on the front cover of US magazine Vanity Fair in 2018, posing with the Queen.
The Queen has owned 30 corgis, all of which are said to be descended from a pet called Susan, which was given to her as a gift on her 18th birthday.
Whisper, the Queen's last purebreed Corgi dog, died six months after Willow did in April 2018.
Willow was a 14th-generation descendant of Susan, and was put down after a cancer-like illness.