Ripley, a California search dog combs the rubble in Kathmandu for a live human scent, as Nepalese and American search and rescue teams await his cue, April 30, 2015.

The United States sent two Task Forces (California Task Force 2 and Virginia Task Force 1) to Nepal on Sunday, after the Nepalese government specifically requested canine disaster search teams to aid in the rescue and recovery efforts currently underway on the ground there.

The California contingent included six canine-firefighter search teams trained by the National Disaster Search Dog Foundation (SDF).

They boarded military aircraft bound for Katmandu on Sunday night as part of a 57-person rescue force that includes structural engineers, hazmat experts, doctors...and canine disaster search teams.

And just when it looked like the search mission in Kathmandu had become one of recovery, the hero dogs were among the search and rescue workers that pulled a fifteen-year-old boy out of the rubble alive, April 30, 2015.

Pemba Tamang had been buried under the demolished Hilton Hotel in Kathmandu, since the catastrophic earthquake struck Nepal on April 25, 2015.

By the time he was rescued, he had endured five days without food, water or the ability to move; trapped in a space smaller than a coffin.

Truly man's best friend, search dogs from around the world heeded the call to search for survivors among the rubble in Nepal.

Here, a Spanish search and rescue dog leads his human counterparts down into the shaky remains of a collapsed building, sniffing for the "live scent" of earthquake survivors among the debris, April 28, 2015.

They came from Holland...

Here, members of the Dutch Urban Search and Rescue team board a plane for Nepal with their tracker dogs at Eindhoven Airport, April 26, 2015.

They came from France...

Here, French firemen scour the Nepalese rubble with one of their rescue dogs for any signs of life, April 28, 2015.

They came from Poland...

Here, a Polish search and rescue dog works his way into tight crevices, searching for survivors, May 1, 2015.

And they came from China...

Here, Chinese search and rescue dogs await marching orders with their human counterparts, April 26, 2015.

Now, let's get to know a few of of these heroic canines a little better... starting with Tanker.

Together, Tanker and Gary form one-sixth of California Task Force 2, one of the elite rescue and recovery squads deployed from America to Nepal on Sunday, in response to a request from their government.

Tanker came to the Search Dog Foundation in an unusual way. Formerly known as "Tank," he was donated to SDF by a previous handler, who had not yet certified with the handsome lab, and felt he might be more successful with someone else.

His loss, Gary's gain.

Gary Durian and Tanker trained intensively to learn how to trust one another and work together as a team. They achieved FEMA Certification in June 2012, which allows them to deploy to disasters around the world.

At four-and-a-half years old, Tanker was older than the average canine candidate accepted at SDF, but he excelled in initial testing and sped through training because of his prior experience.

In fact, trainers describe him as agile, determined and "beautiful to watch," when he's navigating a pile of rubble.

In 2014, Tanker and Gary were sent on the following deployments:

June 20 - Missing Person Search - Fillmore, California
August 4 - Mudslide - Mt. Baldy, California

Originally named "Squirt," Ripley was recruited from Sioux City Animal Adoption & Rescue Center in Iowa, back in 2013.

His boundless energy and toy-obsessive personality -- the very behaviors that probably landed him in the shelter in the first place -- caught the eye of a recruiter, seeking dogs that could have rewarding careers as working dogs.

That recruiter, Kellee Matthews of the South Dakota Canine Center, sent word back to SDF: "This boy is all go, go, go, all the time."

She then went through a full evaluation with Ripley and he passed every test with ease.

Ripley is reportedly so bold and fearless on rubble that trainers had to focus on slowing him down and teaching him how to think things through on a pile. He's just so manic about toys that he won't let anything get between him and his reward... A fantastic quality in a search dog.

After several months of formal training, Ripley was paired with Los Angeles County firefighter Jason Vasquez on April 1, 2014.

He now lives with the Vasquez family and travels to the fire station every day with Jason, so they can train in between calls.

Here, Jason and Ripley search for survivors among the debris of a collapsed building in Kathmandu, April 30, 2015.

In May 2011, Rugby was paired with Los Angeles County Fire Department Captain Dennis Clark.

Rugby then joined Dennis and his family at their home in Fullerton, California, where he enjoys two human and three canine siblings (a Chihuahua, a Great Dane and a Black Lab).

Dennis and Rugby achieved FEMA Certification in February of 2012 and are now able to respond to disasters locally, nationally, and internationally as part of California Task Force 2 based in Los Angeles County.

After learning the basics at SDF's Prep Kennel in Castaic, California, Rugby entered advanced training at Sundowners Kennels in Gilroy, CA.

He quickly learned obedience commands, how to walk on uneven surfaces, and most importantly, the sustained "bark alert" search dogs must perform when they find someone buried beneath rubble.

For having such long legs, SDF's trainers were amazed at how gracefully Rugby is able to traverse rubble piles; a quality which is sure to serve him well on the hunt for survivors in Nepal.

Like many of her search dog peers, Pearl had a tough start to life.

Her original owner was rarely home and, desperate for a little fun, Pearl would frequently jump the fence and end up at animal control.

Sick of having to repeatedly pay their 'bailout' fee, Pearl's owner surrendered her to the local county shelter.

Then, her world changed.

While scouting the local shelters for potential search dogs, a volunteer canine recruiter from SDF had Pearl evaluated. It turned out the toy-crazy Black Lab possessed all the qualities needed in a Disaster Search Dog: intense drive and determination, boldness, athleticism, and the ability to focus on the task at hand.

"Within five minutes, I knew we had a winner," says SDF Lead Trainer Pluis Davern.

"This dog just couldn't sit still. All she could think about was finding and retrieving the toy. If the toy went into dense shrubs, Pearl would barrel in and find it."

Pearl was partnered with Captain Ron Horetski of the Los Angeles County Fire Department.

"Pearl searches like a bullet over any terrain," he says proudly of his partner.

After ten months of intense daily training, Ron and Pearl attained FEMA Certification in May of 2009. And they didn't have to wait long for their first deployment -- a building collapse in La Puente, Calfornia in July 2009.

Just six months later, on January 14, 2010, they would be called to one of the biggest disasters to hit the Western Hemisphere in 200 years: a 7.0 magnitude earthquake on the island nation of Haiti.

As part of California Task Force 2, Ron and Pearl were deployed to Port-au-Prince and searched for 16 days.

This photo shows Pearl combing the wreckage in search of victims still alive under the acres of concrete and debris there.

Together with six other Canine Disaster Search Teams, Ron and Pearl rescued 12 people from the rubble.

Stetson was donated to SDF in June 2010 by the Labs and Friends Rescue in San Diego, Calfornia.

In May 2011, four new handlers from the Los Angeles County Fire Department passed training and were ready to be paired with the search dogs from his graduating class.

When Captain Andrew Olvera showed up at the kennels to be matched, he and Stetson had an immediate connection.

"My first impression was that Stetson was a 'gentle giant,' but he is anything but gentle," Olvera says.

"He is a big, strong dog and proves so when searching -- he drags me around like a 10-year-old on a skateboard."

After logging hundreds of training hours, the team became FEMA Certified in February 2012.

A year later, they got their first assignment, when a house collapsed in East Los Angeles and it was feared people may have been trapped inside.

Stetson and Andy train weekly at rubble piles around the Los Angeles area, and work on obedience training daily, so that they'll be ready when disasters -- like the one in Nepal -- strike.

Riley was adopted -- and then surrendered -- by two separate families, before finding his way to SDF and becoming a search dog.

The first was an elderly couple, who couldn't care for the increasingly rambunctious pup. The second was a young family, in which an excited Riley kept knocking over their two kids.

Luckily, though, the latter enrolled him in training courses at Sundowners Kennels in Gilroy, California, before throwing in the towel. SDF dogs are trained there and the trainers quickly recognized Riley's potential, offering to take him off the frustrated family's hands.

Soon after Riley was admitted to the formal training course, he learned how to climb on rubble, navigate obstacles and bark at a tube where a "victim" was hidden.

In fact, he reportedly sailed through training, due to his "exuberance" and constant desire to be doing something... the very qualities that got him in trouble in his prior homes.

Here, Riley practices his ladder descent skills.

Eric and Riley earned their FEMA Certification in 2010, but continue to train intensively to maintain the very specific, high-level skill set needed for disaster search.

In addition to their regular daily training on obedience and obstacles, the team travels to Los Angeles at least twice a week for search training with the Los Angeles canine training groups.

On March 11, 2011, Eric and Riley were one of six SDF-trained Canine Disaster Search Teams deployed to Japan with California Task Force 2.

The 72-member Los Angeles based Task Force was mobilized by USAID and sent into the Earthquake-Tsunami disaster zone in Japan to comb the wreckage in search of live victims.

Here, Eric and Riley arrive in Japan to search for survivors of the devastating tsunami and earthquakes there in 2011.

In Japan, just like Kathmandu, they were among an elite group of highly trained first responders.

As you can see, these hero dogs have travelled to countless sites of attacks and natural disasters throughout the world.

In fact, since 9/11, SDF search teams have been called upon by state agencies across the country to serve as the first responders to numerous disasters, including hurricanes, earthquakes, mud slides, train derailments and building collapses.

This photo shows Riley combing wreckage in Japan for possible survivors.

Stetson also excels at combing rubble, searching for a scent.

Here, Ripley appears simultaneously determined and adorable, while crushing his training at an SDF facility.

It's probably difficult to stay serious all the time, when your partner's giving you puppy eyes.

You know what they say about all work and no play, though.

It's important to take a moment and just let loose.

So, don't be surprised if you see a hero dog occasionally behaving like your family pet.

They love saving lives, but they also love -- say -- playing a game of tug-of-war.

Because, at the end of the day, these heroes are dogs... which is perhaps the most amazing thing of all.