"He tells me, just come in for a little while. The puppies are upstairs. You can take one home to your son," Michelle Knight said on the syndicated talk show "Dr. Phil."
Knight said Castro trapped her in a room and bound her with an extension cord, and later wrapped a chain around her neck and shackled her to a metal pole in the basement.
"Now, if I do it too tight and you don't make it, that means you wasn't meant to stay here. That means God wanted to take you," she recounted Castro telling her in 2002.
It wasn't until May of this year that she and two other women, Amanda Berry and Gina DeJesus, were freed.
Knight, 32, said she was raped, starved and beaten through the years, spending time "tied up like a fish." At times, he chained her to the pole with a motorcycle helmet over her head.
Castro impregnated her several times, she said.
Knight said begged him with success to release her.
She said he would throw money at her, CNN reported.
"He was obsessed with prostitutes, and also he thought I was a 13-year-old prostitute," she said. "When he found out my real age, he got mad."
Castro pleaded guilty to hundreds of charges and was sentenced to life in prison. He was found hanged to death in his cell in September.