Hulk, a military working dog with the U.S. Air Force's 628th Security Forces Squadron, completes an obstacle course Sept. 24, 2014, at Joint Base Charleston, S.C. The obstacle course was designed to prepare the dogs for challenges they will face at their home stations and during deployments.
(DoD photo by Senior Airman Dennis Sloan, U.S. Air Force/Released). Original public domain image from Flickr