Disaster relief is flooding into Moore, Okla., but along with volunteers and supplies, there are dogs.

Some, including the 11 canine disaster search teams trained by the Search Dog Foundation or SDF, are scouring tornado debris for survivors. Others are en route to comfort the devastated city’s residents. Lutheran Church Charities, whose therapy dogs have worked with victims of the Boston bombings and the Newtown, Conn., shootings, is sending six dogs from its Chicago headquarters.

When disaster strikes, man’s best friend is often there, working on the frontlines of rescue efforts, as well as behind the scenes, helping people cope with trauma and loss.

Super sniffers

Experts estimate that one search-and-rescue (SAR) dog can accomplish the work of 20 to 30 human searchers. Because of these unparalleled abilities, the number of trained SAR dogs has been rising across the United States.

Dogs make efficient searchers due to their superior vision, hearing and sense of smell. A dog’s nose is about 100 times more sensitive than a human nose, and SAR dogs are trained to locate human scents amid countless other smells. They track our scents by the 30,000 to 40,000 dead skin cells we drop every minute.

"Dogs aren’t miracle workers, but their noses are so precious," said SDF founder Wilma Melville. "They can find those people who survived a horrific ordeal."

SAR dog at a disasterAir-scent dogs are trained to work in specific types of terrain. Some search in wilderness settings while others search urban environments, which often can involve scouring collapsed buildings.

Because they must navigate unstable terrain, urban SAR dogs are some of the most highly trained canines. The only national standards for such dogs are the Federal Emergency Management Agency's certification standards for urban disaster work. Currently, fewer than 100 dog-handler teams in the U.S. have this certification.

In addition to air-scent dogs, there are dogs taught to seek out both skin cells and the smell of human decomposition. During major disasters, such as the 1995 Oklahoma City bombing and the 2001 collapse of the World Trade Center, both air-scent dogs and cadaver dogs were used to search for people.

This caused problems for SAR dogs because they became discouraged when they found only dead bodies. At both Oklahoma City and Ground Zero, handlers hid in rubble so that dogs could occasionally find a living person. The dogs’ desire to elicit a response from a found person may be a result of their training, which involves seeking feedback and rewards, but experts say it could also speak to a deeper connection with humans.

Man's best friend

When disasters occur, dogs do much more than just aid search-and-rescue missions. They’re often there to provide a source of comfort for us in ways that only an animal can.

In an interview with American Thinker, Debra Tosch, executive director of SDF, explained how her SAR dog Abby was able to console a firefighter at Ground Zero. "When someone was found, work would stop, and I watched as the tears rolled down the firefighters' faces. I remember one firefighter who hugged Abby and buried his face in her neck after just finding out a fellow firefighter was found," she said.

Research show that petting dogs can lower anxiety, regulate breathing and decrease blood pressure, and a Japanese study found that simply looking at a dog can increase oxytocin levels. Oxytocin is a chemical released by the pituitary gland that’s associated with human bonding and affection.

But while the firefighter may have found comfort in Abby’s presence, was the dog able to empathize? Research says it’s very likely.

A 2012 study at Portugal's University of Porto found that dogs yawn even when they hear only the sound of a person yawning, providing strong evidence that dogs are able to empathize with us.

And a study at the University of London Goldsmiths College found that dogs comforted people — both their owners and strangers — when the person pretended to cry.

"I think there is good reason to suspect dogs would be more sensitive to human emotion than other species," Custance told Discovery News. "We have domesticated dogs over a long period of time. We have selectively bred them to act as our companions. Thus, dogs that responded sensitively to our emotional cues may have been the individuals that we would be more likely to keep as pets and breed from."

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Inset photos: SAR dog at site of 9/11 Pentagon crash: Wikimedia Commons; Woman hugging dog: dennisandluba/flickr