Sgt. Shawn Eden, Quantico Canine Unit, and his working dog Segal participate in an iron dog competition Oct. 23 aboard Marine Corps Base Quantico. Military working dogs and their handlers often collaborate with outside agencies to improve detection training and bite-work training. - Sgt. Shawn Eden, Quantico Canine Unit, and his working dog Segal participate in an iron dog competition Oct. 23 aboard Marine Corps Base Quantico. Military working dogs and their handlers often collaborate with outside agencies to improve detection training and bite-work training.