Prince William and Kate Middleton, the Duchess of Cambridge, announced on Sunday that their family dog Lupo died last weekend.
The couple posted the news on Instagram in order to mourn their beloved pet with their followers.
"Very sadly last weekend our dear dog, Lupo, passed away. He has been at the heart of our family for the past nine years and we will miss him so much," the post read.
James Middleton, Kate Middleton's brother, also shared a post memorializing Lupo.
"Nothing can ever prepare you for the loss of a dog. For those who have never had a dog, it might be hard to understand the loss. However for those who have loved a dog know the truth: a dog is not just a pet; it is a member of the family, a best friend, a loyal companion, a teacher and a therapist," James Middleton wrote.
Lupo, a black cocker spaniel, became part of the family in 2012, before the birth of the royal couple's first son, Prince George.
Prince George and Lupo starred in many official photos together during the dog's lifetime.
The royals have long been dog lovers.
Meghan Markle and Prince Harry adopted a black Labrador retriever, Pula, in 2018.
Queen Elizabeth has had many dogs during her life, although the last of her beloved corgis reportedly died in 2018.