While expecting their first child, Ashlee Simpson and husband Pete Wentz of Fall Out Boy were concerned how their aggressive, but beloved, English bulldog Hemingway would react when the baby arrived. The couple hoped a canine companion might help, but when 5-month-old English bulldog Rigby joined the budding family, Hemingway’s dog aggression escalated. As Ashlee’s due date rapidly approached, Cesar Millan of National Geographic’s ‘Dog Whisperer’ was called in to help the create a balanced environment that will be safe for their newborn. Watch a preview of the episode, airing Sunday, December 28th at 8pm ET/PT, below.