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)

A massive sand storm cloud is close to enveloping a military camp as it rolls over Al Asad, Iraq, April 27, 2005. (Photo by Cpl. Alicia M. Garcia, U.S. Marine Corps/Reuters/U.S. Department of Defense)

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.

Annual celebration of Dinagyang festival of Iloilo, Philippines. (Photo by Raniel Jose Castañeda/Sony World Photography Awards)

Brush your teeth and get cleaned up for the week ahead! These animals answered the call of good dental hygiene. Here: Hamster holds toothbrush. (Photo by Neo Vision/Getty Images/Amana Images RM)

Everton fan and legendary fashion photographer Matt Lever has captured the dizzying drama behind the scenes at catwalk shows since 1999. Here: Balmain, Spring/Summer 2011. (Photo by Matt Lever)

“Natacha Pisarenko was born in Buenos Aires and studied photography at that city’s School of Photographic Arts. Pisarenko currently works out of Buenos Aires, Argentina. She started her career in 1988 as a photographer for La Nación, one of Argentina’s largest newspapers, then joined the AP in Buenos Aires in 2002”. – Associated Press. Photo: A fan wearing leggings marked with the stripes of Great Britain's flag rests on the grass at the rowing venue in Eton Dorney, near Windsor, England, at the 2012 Summer Olympics, Monday, July 30, 2012. (Photo by Natacha Pisarenko/AP Photo)

Sue Bunclark, 40, from Rotherham poses for a photograph besides her 1964 first generation or T1, split-screen Volkswagen Transporter Samba van in Newquay on August 6, 2014 in Cornwall, England. The van, which she and her family have owned for five years is nicknamed Sammy. The Volkswagen Transporter was first produced in 1950 and has sold over ten million units worldwide evolving through five generations of functional and practical body styles, each representing the ultimate multi-purpose vehicle of its time. To commemorate the model's 60th anniversary in the UK Volkswagen has launched a special edition of the Transporter dubbed the Sportline 60. (Photo by Matt Cardy/Getty Images)