A polar bear fast asleep at London Zoo. (Photo by Fox Photos/Getty Images). 1961

Margaret Morris dancers exercising on the sands at Saint-Idesbald. (Photo by Fox Photos/Getty Images). August 1929

Sakia Corona, 8, (C) takes part in a rehearsal of the Contemporary Haitian Dance in a communal center in downtown Havana January 30, 2015. Nearly 25 people, from the Haitian Contemporary Dance Company Petit Fey or Small Leaf, in Haitian Creole, rehearse a play called Papa Guede for future presentations in Havana. (Photo by Alexandre Meneghini/Reuters)

In this June 20, 2014, file photo, lobsters are processed at the Sea Hag Seafood plant in St. George, Maine. More and more American and Canadian-caught lobsters have been turning up at fancy restaurants in China, marketed as “Boston lobster”, say Maine-based processors. One processing firm owner says it's now the biggest live lobster important day of the year after Christmas in Europe. (Photo by Robert F. Bukaty/AP Photo)

In this photo posted on Twitter, Sunday, May 3, 2015, and provided by NASA, Italian astronaut Samantha Cristoforetti sips espresso from a cup designed for use in zero-gravity, on the International Space Station. Cristoforetti, the first Italian woman in space, fired up the first espresso machine in space, which uses small capsules, or pods, of espresso coffee. (Photo by AP Photo/NASA)

Students exercise in body training at Bishan Vocational Education Center in Chongqing, southwest China, January 13, 2016. These students were trained to be stewardesses of the high-speed train. (Photo by Xie Jie/Xinhua)

Throughout the course of the long war in Afghanistan, Coalition troops have relied on thousands of military working dogs to help keep them safe, and make their jobs easier. The dogs are trained to detect explosives, to find illegal drugs, to search for missing comrades, or target enemy combatants. Not only are they active on the front lines, but behind the lines they serve as therapy dogs, service dogs, and loyal companions. They also share the same risks as the ground troops, suffering injuries and sometimes death on the battlefields. Gathered here are images of these dogs and their handlers in Afghanistan and back home, from over the past several years, part of the ongoing series here on Afghanistan.

An angler fishes on the opening day of the salmon fishing season on the River Tay at Kenmore in Scotland, Britain January 16, 2017. (Photo by Russell Cheyne/Reuters)