U.S. Air Force Staff Sgt. Timothy Castillo, 7th Security Forces Squadron military working dog trainer, goes through different obstacles with his dog, Axa, Aug. 10, 2015, at Dyess Air Force Base, Texas. The obstacle course is used to teach obedience and discipline that is put into action when military working dogs are on patrols and conducting searches. (U.S. Air Force photo by Airman 1st Class Austin Mayfield/Released)