Prince William and Kate Middleton's beloved dog Lupo dies: 'We will miss him so much'

The royal family made the heartbreaking announcement on Sunday.
/ Source: TODAY

Prince William and the Duchess of Cambridge made a heartbreaking announcement on Sunday: Their dog Lupo has died.

"Very sadly last weekend our dear dog, Lupo, passed away," they shared on Instagram. "He has been at the heart of our family for the past nine years and we will miss him so much."

No cause of death for the English cocker spaniel was given.

According to Hello, the couple added Lupo to their family back in 2012. He was a gift from Kate's brother, James, after their wedding. In 2016, the royal pup was famously photographed playing with Prince George, getting a taste of his ice cream, in the photos Kensington Palace shared for the prince's third birthday.

Prince George, who celebrates his third birthday on 22 July 2016, balancing on a wooden swing. The picture was taken at the family's Norfolk home in mid-July by Matt Porteous.Matt Porteous / PA

Lupo left an indelible mark during his time at Kensington Palace. Animal groups attributed the raised profile and interest in cocker spaniels to Lupo, citing a notable increase in searches on the U.K. Kennel Club website in the months after the Cambridges welcomed Lupo.

Prince William, Duke of Cambridge carries his dog Lupo attend The Golden Metropolitan Polo Club Charity Cup polo match, in which Prince William, Duke of Cambridge and Prince Harry played, at the Beaufort Polo Club on June 17, 2012 in Tetbury, England.Max Mumby/Indigo / Getty Images

Lupo has even been represented in children's literature. Author Aby King signed a four-book deal to write about the fictional adventures of Lupo, pitted against Queen Elizabeth's famous corgis. The first book, called "The Adventures of Lupo the Royal Dog: The Secret of Windsor Castle," was published in September 2014.