What did Mr. Benson say about Old Dan and Little Ann that surprised Billy?

From the text:

Mr. Benson took a deep breath to control himself, and started again in a much calmer voice. "Those two hounds," he said. "I found them. They're frozen solid. They're nothing but white ice from the tips of their noses to the ends of their tails."

Hearing Mr. Benson's words, I screamed and ran to my father. Everything started whirling around and around. I felt light as a feather. My knees buckled. I knew no more.