Lisa Yu crawls through a mud pit under low slung barbed wire as she competes in The Tough Bloke Challenge on March 4, 2012 in Melbourne, Australia. The Tough Bloke Challenge is one of the most gruelling adventure runs in Australia consisting of 18 obstacles over a 6 km cross-country course laden with thick mud-pits and ice-cold water crossings. (Photo by Scott Barbour/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.

Nino, a ten-year-old toreador apprentice of the French Tauromachy Centre, nicknamed El Nino, touches a practice bull at the bullring of Garons, near Nimes, September 25, 2013. Since 1983, the French Tauromachy Centre in Nimes has trained some 1,000 youths in the art of bullfighting. Twenty of them have gone on to become professional matadors, facing fighting bulls in the arena. Twice a week, students take courses with a matador to learn the movements and gestures of the bullfighter in the ring, but without an animal present. Students train with calves in the surrounding fields during spring, and regularly participate in beginner's bullfights (becerradas) without killing calves. Solal has been taking courses for three years and Nino, for just a year now. Both are normally enrolled in French public schools, but have one thought in mind – bullfighting. They share a passion linked to the city of Nimes, famous for its ferias and bullring. (Photo by Jean-Paul Pelissier/Reuters)

Then U.S. Army First Lieutenant Kirsten Griest (C) and fellow soldiers participate in combatives training during the Ranger Course on Fort Benning, Georgia, in this handout photograph taken on April 20, 2015 and obtained on August 20, 2015. When Griest and another woman completed the daunting U.S. Army Ranger school this week they helped end questions about whether women can serve as combat leaders, as the Pentagon is poised to open new roles, including elite Navy SEALs, to women in coming months. The feat by Griest and First Lieutenant Shaye Haver followed a re-evaluation of the role of women after their frontline involvement in Iraq and Afghanistan and the end of a rule barring them from combat roles in 2013. (Photo by Spc. Nikayla Shodeen/Reuters/U.S. Army)

Boat crew members train on the waters of the Tonle Sap River on the morning of the first day of the Water Festival on November 13, 2016 in Phnom Penh, Cambodia. The yearly three-day Water Festival is one of the most important holidays in Cambodia and celebrates the end of the rainy season and the start of the rice harvesting. The Festival also coincides with the Tonle Sap river reversing course, which it does twice a year. Approximately 2 million people are expected to attend this year's festival, during which 259 boats and nearly 20,000 oarsmen will participate in the races. After a fatal stampede resulting in the death of some 353 people during the Water Festival in 2010, it has been cancelled four times over the past five years, with weather used as an official excuse. (Photo by Omar Havana/Getty Images)

Children watch a rabbit, jumping over a hurdle at an obstacle course the 5th Open Rabbit Sport Tournament (5. offene Kaninchensport Turnier) on August 28, 2011 in Rommerz near Fulda, Germany. Eighty rabbits competed in light-weight, middle-weight and jumping-for-points categories at today's tournament in Rommerz that is based on Kanin Hop, or Rabbit Hopping. Rabbit Hopping is a growing trend among pet rabbit owners in Central Europe and the first European Championships are scheduled to be held later this year in Switzerland. (Photo by Ralph Orlowski/Getty Images)