Yes, Boo was a real dog. He was a Pomeranian who gained immense popularity on social media platforms like Instagram and Facebook, becoming known as the "world's cutest dog."
Sadly, Boo passed away in 2019. A Today.com article reported on his passing and his widespread fame. His owners attributed his death, in part, to a "broken heart" following the death of his companion dog, Buddy. Boo was 12 years old.
In summary, Boo was a real Pomeranian dog who achieved considerable fame online for his adorable appearance.