In a heartbreaking message posted to their Kensington Royal Instagram account, the Duke and Duchess of Cambridge mourned Lupo, calling him “the heart of our family for the past nine years.”

“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. – W & C,” the post read.

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An English cocker spaniel, Lupo was gifted to William and Kate, both 38, as an early Christmas present in 2011, according to The Sun. He is said to have been bred from a dog owned by Kate’s parents, Carole and Michael Middleton.

In addition to the Cambridges, Kate’s younger brother, James Middleton, 33, also posted an emotional tribute to Lupo on social media.

“It is with great sadness that Lupo, the beloved dog of my sister Catherine and her family has passed away. Lupo was the son of Ella, brother to Zulu, Inka & Luna. He was 9 years old,” James wrote Sunday.

“Rest in peace Lupo. Tilly & Mini will be waiting for you. You will always be remembered and your legacy will live on forever. Good Boy,” he continued.

Lupo was featured in several official portraits over the years, including a sweet family shot of the Cambridges after Prince George’s birth in 2013.