Doc, an improvised explosive device detection dog (IDD) with 2d Combat Engineer Battalion, retrieves a bumper during a training session at Camp Leatherneck, Afghanistan, March 19, 2013. IDD dog handlers, often volunteers from their home units, are matched with a dog and work together to perform route clearance and other duties in a combat environment. (U.S. Marine Corps Photo by Sgt. Tammy K. Hineline/Released)