Lil Bub, the rescue cat who became a social media star, has died in the US at the age of eight, her owner Mike Bridavsky has announced.

Bridavsky shared the news with Lil Bub's 2.3 million followers on Instagram, writing: "On the morning of Sunday, December 1st 2019 we lost the purest, kindest and most magical living force on our planet. BUB was cheerful and full of love laying in our bed with us Saturday night, but unexpectedly passed away peacefully in her sleep."

"It is impossible to put into words the profound effect that BUB has had on my life, on the lives of thousands of homeless pets, and on the lives of those of you that have cared for her as if she were your own family," Bridavsky continued. 

He said Lil Bub "taught me everything that I know about unconditional love", describing her as "a constant source of warmth and love in our lives for the past 8 years". 

Bridavsky told Lil Bub's followers that the feline made "a huge difference in the world of animal welfare, and in the lives of millions of people worldwide". She "had literally saved thousands of lives (both pets and humans)", helping to raise "over $700,000 for animals in need" in the process.

"To say that our family is devastated would be an understatement," he said.

Lil Bub was rescued by Bridavsky in 2011 after being found in a shed. She was a permakitten - staying kitten-sized all her life - and, as her website says, had an "extreme case of dwarfism". Because of the fact that she never grew a full set of teeth and had jaw problems, her tongue was always visible.

"Dearest BUB, I will never forget your generosity, your limitless supply of love, or your uncanny ability to bring so much magic and joy to the world," Bridavsky concluded. "I am forever honored and humbled that you chose me as your caretaker. Please visit all of us in our dreams."