"He has been at the heart of our family for the past nine years and we will miss him so much," the Duke and Duchess of Cambridge wrote on the KensingtonRoyal Instagram account on Nov. 21 as they announced the sad news.
James Middleton, the duchess' brother, is also a dog lover. He has several of his own dogs and has written about how they were helpful to him while he was battling depression years ago. He shared his sadness on Instagram as well.
"Nothing can ever prepare you for the loss of a dog," James wrote. "For those who have never had a dog, it might be hard to understand the loss. However, 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 wrote that Kate and William losing Lupo had brought back some pain from the death of his first dog, Tilly, in 2017.
"There isn't much of a rule book on how to grieve for a dog, but I've said a prayer, lit a candle and taken Ella for a long walk to spend time remembering Lupo."
Lupo was bred from Ella, a dog owned by Kate and James's parents, Michael and Carole Middleton, in December 2011. At the time, there were reports the pup had been named after Olive Christina Middleton, one of Kate's grandmothers. Her original surname was Lupton and the family crest featured wolves.
Lupo had been featured in several important official photographs with members of the Cambridge family, including Prince George. The dog appeared in a picture taken shortly after the birth of William and Kate's first child, along with other family portraits. The very good boy was also beloved by members of the Royal Family, with Prince Harry frequently pictured saying hello to him at events such as the annual charity polo match.
We're sending the Cambridges and Middletons our best thoughts at this difficult time.