SINKING SPRING, Pa. -- When Libby the 14-year-old therapy dog enters the room, folks light up.
It's when Libby plants her feet firmly on the ground and refuses to enter a room that things get more complicated.
Her owner says the therapy poodle knows when someone is about to die, NBC 10 medical reporter Cherie Bank reported.
"The first few times, I really didn't put it together," said Marge Stiller, the poodle's owner and trainer.
Stiller said when Libby won't pass the threshold, it's because "she has the ability to know -- I don't want to say predict -- know when a person is going to be passing away within 24 hours."
And Marge said Libby's track record is pretty "dog-gone" good, Bank reported.
"It's 100 percent. It's been 100 percent, yeah," Stiller said.
Stiller has been taking Libby to nursing homes, rehab hospitals and retirement communities for about 12 years.
She said she began to put two and two together after seeing newspaper obituaries days later of the people Libby wouldn't visit.
Stiller said this is the first time she's publicly admitting her beloved canine's special skill. She said it only happens around older folks and she never tells the people whose room Libby won't go in.
"I've seen her walk away from people who have tried to pet her or something, but I try to make myself believe she's just headed in another direction," Stiller said.
Researchers say dogs have an incredible sense of smell humans can only dream about. Dogs have already been proven to detect bladder cancer and breast cancer.
"They have also, apparently, been shown to be able to tell the difference between a mole on your skin and a melanoma, a skin cancer, on your skin," said Penn Veterinary Medicine's Dr. James Serpell, who studies human-animal interactions.
"All with their sense of smell? " Bank asked.
"Just with their sense of smell," he answered.
Serpell said most likely Libby smells the changes in body chemistry that happen just before someone dies.
"I think it's highly likely, yes," he said.
"You're a good girl. I love you so much," Stiller said, petting Libby.
Stiller said she never worries about Libby sensing her death.
And as far as when Libby may pass?
"She can't leave this earth until I do," Stiller said.