Beth Chapman has been placed in a medically-induced coma.
The 51-year-old reality star - who is the wife of Duane 'Dog' Chapman - is in the intensive care unit of Queen's Medical Center in Honolulu, and only receiving visitors from her immediate family.
Beth has been receiving treatment for Cancer and her 'Dog the Bounty Hunter' star husband said he and his family "humbly ask everyone to please pray for Beth.
And he added on Twitter: "please say your prayers for Beth right now.(sic)"
In a statement, the family offered their "sincere thanks to everyone for their prayers throughout Beth's battle with cancer."
A spokesperson for the couple confirmed to People magazine: "It's quite serious."
Dog and Beth's daughter, Bonnie, admitted there has been little news about her mother's condition but she was grateful she was receiving "good care".
She said on her Instagram Story: "There's not much of an update I can give, I can say she's getting good care.
"I know you guys wanted more, but y'know it's a coma, not much can be updated."
She also shared a photo of her parents kissing.
She wrote: "If you haven't heard, my mother in an induced coma.
"Please keep her in your thoughts and prayers."
The 'Dog & Beth: On the Hunt' star underwent successful throat cancer surgery in 2017 but last year was told the disease had returned and underwent emergency surgery to remove a tumour in November.
She was hospitalised in April due to fluid accumulation in her longs and underwent an operation in April to relieve pressure.
Dog previously admitted he would "do anything" if it meant his wife would be well again.
He said: "I'm a sinner. I pray a lot. I have done double that. I constantly ask God to heal my honey and make sure He takes care of it. I've been telling Him that I'm going to try and quit smoking and cursing. I'm a dealmaker, and I'll do anything."