When a three-month-old Great Dane puppy started knocking over toddlers and terrorizing a blind senior dachshund in an Indiana household, the Messman family turned to Nathan Lowe for help. “People sometimes are hesitant to correct a little puppy,” Lowe said. “Well, a three-month-old Dane is a big puppy. And it was a very pushy puppy.” Lowe said the most common mistake new puppy owners make is believing that love alone is enough to shape a dog’s behavior.