National Geographic has a video out about Vietnam veteran Richard Steinberg and his service dog Kira, and how she helps him cope with PTSD (Post-Traumatic Stress Disorder).
Steinberg says, "We didn't train the dogs to protect those ARMY airfields or those ammunition storage areas. We trained the dogs to protect the handlers, so what the government did was put me in a dangerous situation but then they gave me the dog to protect me, and we survived."
Steinberg describes how Kira senses when he has nightmares, night sweat and when his "sugar levels are out of whack," as he is also a diabetic. Kira can sense all of this through sensing the chemical changes in Steinberg's body.