For military veterans suffering from PTSD, are service dogs good therapy?

JACKSONVILLE BEACH, Fla. — Adam Fuller credits a simple, one-word command — and a black Lab mix named J.D. — with helping to save his life.

"Cover," he tells J.D., who is sitting to his left in a grassy field next to a park playground. The dog calmly walks to Fuller's right, then sits facing backward. Were someone coming up from behind, he'd wag his tail. The signal quells the sense of threat that plagued Fuller after serving in Afghanistan, that at one point had him futilely popping medications and veering toward suicide.