Dogs aren't just our best friends, they're also key allies in the fight against terrorism. Thousands of teams of explosive detection dogs and their handlers work 24/7 at airports, transit systems, cargo facilities, and public events around the globe to keep us safe. But canine detection is an art as well as a science: success depends not only on the skill of both dog and human, but also on their bond, and may vary with their physiological state and environmental conditions.