Boo, the so-called world's cutest dog, has died in his sleep aged 12.
The little Pomeranian rose to social media stardom after being adopted in 2006. Often referred to as the world's cutest dog, he gained a massive following with more than 16 million likes on his Facebook page.
His owners say he had signs of heart problems ever since his "best friend" Buddy - another dog - died in 2017. They had lived together for 11 years before Buddy passed away at the age of 14.
"We think his heart literally broke when Buddy left us," they posted to Instagram.
"He hung on and gave us over a year. But it looks like it was his time, and I'm sure it was a most joyous moment for them when they saw each other in heaven."
They say they are "heartbroken" at the loss of their beloved pet but "find comfort knowing that he is no longer in any pain or discomfort".
"We know that Buddy was the first to greet him on the other side of that rainbow bridge, and this is likely the most excited either of them have been in a long time," they wrote.
"Boo, we love you with all our hearts and will miss you until the day we meet again. Have fun running around with Buddy and creating adorable mischief wherever you guys go."
You can read their full tribute to Boo in the Instagram post below...