Pop superstar Cher is fraught with worry after her beloved cat fell sick.

The singer reveals her pet, named Mr. Big, is currently undergoing treatment at a veterinary clinic and she is deeply worried as he has never been ill since she adopted him.

She shared the drama with her fans in a series of posts on her Twitter.com page, writing, "Mr. Big is sick in hosp (hospital). My friend Kat is with him, she's top heart Dr (doctor). I was crying... The weird thing is I never think about him sick! He was almost dead when we found him in Detroit, but after that he has never been sick."

Cher posted a number of pictures of Mr. Big and later admitted the cat was starting to show signs of improvement: "Mr Big in his little oxygen tent, getting his Iv of meds (medication) wrapped in blanket, but he's still eating! Nurses love him... Kat, his heart Dr. says he will be well enough 2 (to) have echocardiogram (a heart scan) tomorrow. Says he's feeling better after meds (sic) & oxygen! Better is good!..

"I'm great in an emergency, but I cry when it's over & everything is fine!"