FORT LEONARD WOOD, Mo. -- Their training is intense, their deployment dangerous.

They are sent to barren fields and dusty roads far from home to search for a major threat to U.S. forces in Iraq and Afghanistan: land mines and other hidden explosives.

Increasingly, the U.S. military is relying on dogs to reduce war casualties.

At Fort Leonard Wood, the Army has created the 67th Engineer Detachment (Mine Dogs). Dogs are deployed along with their soldier-handlers after at least four to six months of training.

Congress thinks enough of the program that it appropriated $3.7 million for a new kennel and training facility that will be built at the post starting early next year. Two additional mine dog units will be added there in the next few weeks, officials said.

"The need is definitely high," said Lt. Erik Karstensen, unit commander.

The dogs, with their superior sense of smell, high mobility and fearlessness, have saved countless lives by finding mines, unexploded ordnance, booby traps and bombs that humans and machines can miss, Karstensen said.

"The dogs are a piece of equipment," Karstensen said. "They speed up the detection process, and they minimize the risk to the soldiers."

But the dogs become more than equipment to their handlers.

"The handlers get very attached to the dogs," Karstensen said.

Laika, a Belgian Malinois, has clearly bonded with Sgt. Jaime Castro, his handler at Fort Leonard Wood. The dog's eyes lock onto Castro as Laika takes orders in an obedience drill. The dog dashes up and over a 7-foot ladder, scales stairways and leaps hurdles, all in a matter of seconds. Castro gives the dog grateful rubs on the sides of his head.

'You can't beat that'

"Animals are very loyal, and you can't beat that," Castro said. "It's an unconditional loyalty."

The Army won't say how many dogs it has at Fort Leonard Wood or in battle, but the unit's kennel has stalls for about 30 dogs and most appear to be in use. Other branches of the military also train dogs for explosives detection on the battlefield and in military police work.

The Army has deployed canine units since World War II, Karstensen said.

In Afghanistan and Iraq, land mines, weapons caches and various improvised explosive devices (IEDs) are a constant danger. In the Iraqi war, about 800 troops have died and more than 8,000 have been injured by various planted explosives -- accounting for roughly half of all deaths and injuries from hostile action, according to U.S. Department of Defense data.

IEDs can be buried, hidden in rock piles, abandoned vehicles, trash or buildings, or even placed in discarded beverage cans.

Land mines are more widespread, and some have been in place for decades. Before the U.S. invasion, some 10 million to 15 million land mines dating to World War II were scattered across Iraq.

Dogs are used to clear routes ahead of convoys or patrols and check larger areas that forces want to move through or use. When there are troop casualties, the dogs clear evacuation routes. When they detect explosives, they freeze or sit.

Karstensen said no Army dog has died from explosives while working in Iraq or Afghanistan. Luckily, the dogs don't understand the risks.

"They don't know what they are doing is dangerous, that they are possibly walking in an uncleared mine field," Karstensen said. "It's all just a big game for the dog. When they find the odor, they get their reward."

The reward is to be played with, Karstensen said.

At Fort Leonard Wood, the play involves chasing and retrieving a rubber, cone-shaped toy. Early this month, however, play proved fatal to one of the deployed dogs when it choked on a toy while trying to carry two at once, said Mike Alley, media affairs officer at Fort Leonard Wood.

The Humane Society of the United States generally has supported use of dogs to locate overseas minefields, which can pose a risk to civilian and animal populations, said Andrew Rowan, the group's executive vice president for operations.

"A human-dog team working together can make the world safer for humans and animals," Rowan said.

But the society has reservations about military use of the dogs in Iraq because in the past, such as in Vietnam, dogs were left behind after the war, Rowan said. "The military has not been terribly grateful for the dogs," he said.

Karstensen said the dogs are highly valued in Iraq and Afghanistan, not only for safety but for companionship.

"They are a morale booster," he said. "Many times other soldiers will come up and want to pet the dog because it may remind them of the one they have back home."

Dogs have been deployed from Fort Leonard Wood since early last year, but the mine dogs did not become an official unit until a year ago.

The military often has used commercially trained dogs and handlers but is gradually taking over most of the program itself, Alley said. "While in some things contracting works great, in some areas we want a soldier there with the dogs," Alley said.

The dogs used for bomb detection are of many breeds. At Fort Leonard Wood, the springer spaniel, Labrador and German shepherd were among breeds in training.

The Air Force acquires dogs for all military branches, Karstensen said. The dogs undergo rigorous obedience training before bomb detection duty. Most do not pass muster and are put up for adoption. The selected dogs usually range in age from 18 to 24 months, Karstensen said.

Laika and Castro spent six months in Afghanistan last year and will return.

"It's very dangerous, but the dogs are well trained," Castro said. "They have a great nose, and I'd rather trust my dog than any human or mechanical means."