Sy Montgomery took this call on her friend’s cell phone in a car somewhere in the San Francisco Bay area. She is on a book tour promoting “How to Be A Good Creature: A Memoir in Thirteen Animals,” her twenty-first.

Her favorite animal is Thurber, her border collie “with a big stripe down his face like a lightning bolt down in front of his nose and a blind eye,” she says. Why? “He has taught me that no matter how hopeless things look there could be a miracle around the corner,” she said.

Montgomery was in a horrible depression after her dog Sallie died of a brain tumor. Thurber...