The 12-year-old Pomeranian’s owners announced the sad news on Friday on Facebook.
“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.”
According to the statement he suffered from heart issues after his brother Buddy died in 2017.
“Shortly after Buddy died, Boo showed signs of heart issues. We think his heart literally broke when Buddy left us. He hung on and gave us over a year.”
The cute dog had a huge following on social media with 16 million followers on Facebook alone.
Boo rubbed shoulders with many celebrities including Anderson Cooper, Liam Payne and Seth Rogen.
In 2011 he even released his own book, Boo: The Life of the World’s Cutest Dog.