What does the title,the sold rope,of chapter 12 mean?

Paul is wakened by his grandfather in a soft voice as to not spook the animals. He tells Paul to go on up to the house so he can have something to eat and get warmed up. His grandmother had been very worried about him since he hadn't come home from the storm. Later on that day Maureen makes her way down to the corral where she sees Misty with a sold rope on her neck. This comes as a shock and is an unsettling sight to Maureen. She begins crying. The chief sees her and asks what has happened. Maureen explains about Misty being sold, and the chief asks her why they didn’t come to him sooner. Maureen feels bad for the fire chief because she realizes he has never wanted anything since his family is well off.