“I want to tell him to sit again,” Lee Jones, 11, of Brierfield, Ala., tells Melannie Layne.

Layne glances at her dog Mike, who is being petted by some of Jones’ cousins visiting him at St. Vincent’s Hospital in Birmingham, Ala. To get the dog’s attention, Layne doesn’t whistle or call his name. She reaches over and touches the white Australian Shepherd on the back. He turns immediately to face his owner.

“Come here,” Layne, of Trussville, Ala., mouths quietly while circling her hands one over the other toward her body. Mike retreats a few steps from the adoring fans. “Look over here,” she says, pointing at Lee.

Lee says nothing, but makes a sort of alligator hand puppet with his thumb and two fingers, closing them together. Mike sits. The thrilled child leans forward and gives the dog a hug.

Most dogs don’t know the hand signal to which Mike responded, but many people do. Born deaf, Mike has learned American Sign Language — or at least the 30 or so signs that Layne has taught him in his five years. Mike shows off his knowledge as a volunteer pooch with Hand in Paw.

This national organization uses animals like Mike to help people reduce stress and loneliness, increase verbal interaction and gain a sense of trust.

Layne and Mike first met Hand in Paw representatives at the Pets America store in Hoover, Ala., in 1999. Mike, Layne and her two daughters were on a routine visit to the pet store, and Hand in Paw was out recruiting interested volunteers.

“I showed them some of the tricks he could do, and … some of them were in tears,” Layne said.

At first she thought the response was a bit over-the-top, but later she began to understand.

“I never realized the impact this could make,” Layne said.