The House of Windsor came by its first corgi in 1933, when King George VI, then the Duke of York, acquired a puppy known as Dookie for his family.

He was joined shortly thereafter by Jane, who was with the royal family until 1944, when she was fatally struck by a car.

Susan was given to Elizabeth later that year, as an 18th birthday present. According to an article in Vanity Fair, Elizabeth, then a princess, became so inseparable with her dog that she sneaked Susan with her and Prince Philip on their honeymoon in 1947.

Over the nearly 80 years since the queen acquired Susan, she and her family have continued to breed dogs from Susan’s lineage. The queen has owned at least 30 Pembroke Welsh corgis, all of whom have descended from Susan. Willow was believed to be part of the 14th generation in the line.

But Willow’s death would signal the end of an era for the queen, who reportedly stopped breeding corgis sometime after the death of her mother in 2002.