Story highlights Landmines and car bombs are still a threat in Colombia

Rats are being trained to sniff out buried explosives

Trainers say a rat's sense of smell is just as good as a dog's

Researcher: With the cost of feeding a dog one day, "you can feed seven rats for seven days"

At a Colombian National Police base in the outskirts of Bogota, the nation's capital, a new recruit is being trained.

This new recruit is unlike any other. It stands on four legs, has white hair all over its body and weighs slightly less than a pound. Its name is Rattus Norvegicus -- but it's more commonly known as a lab rat.

During a recent training session, trainers set the white rat on a patch of grass where they had hidden an explosive device underground. It took the rat less than a minute to find it. The rodent was showered with praise. Its trainers also gave it its favorite reward, a treat.

Though safer than a decade ago, Colombia is a country where landmines and car bombs are still a threat. Earlier this month, six people were killed by a car bomb targeting a police station in the town of Villa Rica in the southern province of El Cauca. The day before the February 2 bombing, nine people were killed and 70 were injured by another explosion in the neighboring province of Narino.

Edgar Ramirez, a second lieutenant with the Colombian National Police, says his country still "faces conflicts such as guerrillas, and criminal and paramilitary groups. There are many disputed territories because of the drug trade or simply to take control, and many groups set up land mines in these territories."

In the past, Colombian police used bomb-sniffing dogs; but the dogs' weight would often trigger the explosives. That's not a problem for lab rats that weigh slightly less than a pound.

And according to the trainers, their sense of smell is just as good as a dog's.

Colombia is not the first country to use rodents in this fashion. Rats have already been put to work in Mozambique to detect landmines.

Ramirez says that the only disadvantage he can think of about using rats is their short life span.

"These animals live only three to four years, which is a relatively short period of time from a human perspective. On the other hand, they're very prolific. They reproduce themselves exponentially in a very short time," Ramirez said.

So far, the rats have been trained to detect seven different kinds of explosives including ammonium nitrate and fuel oil, gunpowder and TNT.

The project is directed by Luisa Fernanda Mendez Pardo, a veterinarian who specializes in canine explosives-detection training. Mendez said that in the last four years her team has produced five generations of between 15 and 18 rodents each.

"As a researcher," Mendez said, "I can tell you that this project has exceeded the expectations we had at the beginning. We have been able to condition the rats to follow simple verbal commands. We have also trained them to not be afraid of their human handlers."

Their trust has also gone beyond humans. The rats even get on with the cat that protects them from other predators at the lab where they're trained.

Mendez also says the rats are much more cost-effective than their canine counterparts. "With the money it takes to feed a dog per day, you can feed seven rats for seven days," Mendez said.

Officials with the Colombian National Police say they expect to take the bomb-sniffing rats into the field in later this year.

"The main goal is to tackle a humanitarian problem in Colombia," says Mendez. "In my career, I have seen many civilians, police officers and soldiers who have been killed or severely injured in mine fields. It has become a personal challenge, and I want to use this project to help my country."

The team has been able to successfully train more than 70 rats in the last four years since the project began. The process has allowed them to acquire important knowledge about how the rodents can help authorities clear fields full of landmines in the Colombian countryside.