Dog Gone! 'World's Cutest Dog' Boo Dead at 12

Boo, the Pomeranian known as "the world's cutest dog," died Friday. He was 12.

Boo's owners mournfully announced the pint-sized pooch's death on Facebook, writing, "With deepest sadness I wanted to share that Boo passed away in his sleep early this morning and has left us to join his best friend, Buddy. Our family is heartbroken, but we 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."

Buddy, Boo's big bro, died in September 2017.

"Boo's humans," as they self-identify, went on to write, "Our family is heartbroken, but we find comfort knowing that he is no longer in any pain or discomfort." The message was a reference to the heart malady that plagued him in his later years.

Blazing a trail for that Instagram egg, Boo was a genuine Internet sensation, with nearly 17 million Facebook likes. His adorableness was so vast it stretched across four best-selling books.