The Question and Answer section for Where the Red Fern Grows is a great resource to ask questions, find answers, and discuss the novel.
From the text:
During the meal I told Grandpa I didn't think that the coon in the big tree was the same one my dogs had been trailing at first.
"What makes you think that?" he asked.
I told how the coon had fooled us and how Little Ann had...
You are correct, he signed Billy and his dogs in the competition.
He uses a baking powder can.