Boo the Pomeranian, who flashed warmth into the lives of the 16 million Facebook fans drawn to his sunny disposition and gentle good humour, his fluffy head and neatly trimmed torso, has died of suspected heartbreak. He was 12 years old.

Along with his friend Buddy, Boo became something of a phenomenon within certain crevices of social media, through the carefully tended accounts run by their owner, who goes under the name JH Lee.

Boo the "world's cutest dog" has died, aged 12. Credit:Facebook

But when Buddy died in 2017, Boo’s heart seemed to feel the impact. “We think his heart literally broke when Buddy left us,” Lee wrote on Facebook over the weekend.

“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.”