Dog Named Mattis: 12 Lessons for Living Courageously, Serving Selflessly, and Building Bridges from a Heroic K9 OfficerSergeant Mark Tappan shares the twelve lessons he's learned from his amazing K9 partner Mattis, whose heroic actions will remind readers to live courageously, serve selflessly, and love passionately because every human (and dog) has a purpose. Sergeant Mark Tappan shares the twelve lessons he's learned from his amazing K9 partner Mattis, whose heroic actions will remind readers to live courageously, serve selflessly, and love passionately because