The Internet-famous feline known as Colonel Meow, who landed a spot in the Guinness World Records for being the cat with the longest fur, is seriously ill, his owner said.
His owners in Los Angeles posted on the cat's Facebook page Monday that the Himalayan-Persian cross-breed was in an animal hospital with a mysterious illness.
"The doctors don't really understand what's wrong with him," the Facebook post read in part. "He needs YOU to send your amazingly good energy, vibes, and prayers."
According to the post, the Colonel survived a 50/50 chance surgery and a blood transfusion that doctors thought would send him into heart failure.
The cat's owners said his heart "isn't doing the best," but he is getting feisty, and that's a good sign.
Supporters from all over the world are posting their support and get-well wishes.
"Darling Colonel, sending our furriest prayers to help you regain your superpowers, we need you more than ever xxx," said one Facebook fan.
The Colonel became an Internet star this year after his owners, Anne Marie Avey and Eric Rosario, began posting photos of him with his now-famous long hair and funny scowl.
The Colonel has fur that reaches 9 inches and he will be featured in the Guinness World Records 2014 book, accord to the Guinness website.