English actress and model Elizabeth Hurley launches Harrods beach and children's wear at the Knightsbridge store in London, England on December 6, 2006. (Photo by Daniel Deme/WENN)

Monsoon thunderstorm in Sierra Vista, Arizona. 9 Sept, 2011. (Photo by Steven Maguire)

An anti-government protester wearing a Guy Fawkes mask stands with a shield near flames from molotov cocktails thrown at a water cannon by anti-government protesters during riots in Caracas in this April 20, 2014 file photo. (Photo by Jorge Silva/Reuters)

Caroline Wozniacki of Denmark serves in her match against Kaia Kanepi of Estonia during day four of the Toray Pan Pacific Open at Ariake Colosseum on September 28, 2011 in Tokyo, Japan. (Photo by Koji Watanabe/Getty Images)

Two drunk race-goers make their way home after the last race of the third day of the Royal Ascot horse racing week June 19, 2003 in Ascot, England. (Photo by Scott Barbour/Getty Images)

“The Portuguese Water Dog is a breed of working dog as classified by the American Kennel Club. Portuguese Water Dogs are originally from the Portuguese region of the Algarve, from where the breed expanded to all around Portugal's coast, where they were taught to herd fish into fishermen's nets, to retrieve lost tackle or broken nets, and to act as couriers from ship to ship, or ship to shore. Portuguese Water Dogs rode in bobbing fishing trawlers as they worked their way from the warm Atlantic waters of Portugal to the frigid fishing waters off the coast of Iceland where the fleets caught cod to bring home. Portuguese Water Dogs were often taken with sailors during the Portuguese discoveries”. – Wikipedia

Photo: Kix, a Portuguese Water Dog , enjoys a walk around the muddy fields near his home before the grooming and preparation starts for this years Crufts on March 3, 2009 in Telford, England. (Photo by Christopher Furlong/Getty Images)

Doris Pennman adjusts her umbrella as she walks along Mission Beach on January 8, 2005 in San Diego, Califonia. (Photo by Sandy Huffaker/Getty Images)

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.