The boy sees the dog from across his hospital room, and his grin is contagious.
Piggy waddles into the room. Hit by a car 2½ years ago, the dog's back legs are paralyzed and she uses her front legs and a doggy wheelchair to drag them behind her.
The pitbull-boxer mix is a therapy dog at Shriners Hospitals for Children in Salt Lake City, where children are often in wheelchairs or casts after receiving free orthopedic surgeries for spinal and leg disorders.
The boy barely talks and doesn't need to. His smile speaks for him as he crawls to the edge of his bed to pet Piggy and toss her a piece of dried chicken jerky.
Seeing reactions like that, April Hollingsworth knows she was right to keep Piggy alive after she was hit by a car.
Whether Hollingsworth is taking Piggy room to room in the hospital, or on runs down Millcreek Canyon, the smiles that follow the dog make her feel like she is passing out $100 bills.
"I feel she's a gift I have to give," she says.
Piggy is one of four therapy dogs that visit the hospital. Despite the reputation pitbulls have, the dog is friendly and calm. Intermountain Therapy Animals tests all of the volunteer dogs to ensure they are controllable, predictable and like to be around people.
Shriners recreation therapist Laura Lewis said the dogs help make the hospital seem less scary and more like home. It gives children a sense of control to feel like they can take care of something else, even if it is just brushing a dog's fur.
"The kids love the dogs," she said. "I've witnessed moments where a child hasn't talked to anyone else but the second that the dog comes in the room, they will just sit down and tell a dog how they're feeling and what scares them."
Hollingsworth brings Piggy, 6, to Shriners every couple of weeks. This week, she stopped by 20 rooms, where children were recovering from surgery or waiting to be fitted for new wheelchairs or casts.
The visits were quick -- enough time for the children to scratch under Piggy's chin or feed her a treat. Piggy lives up to her name, occasionally grunting.
Francisco "Javier" Ramerez, 10, stood in his hospital gown, his right foot in bandages from surgery to straighten it, dropping a tennis ball in front of Piggy.
The New Mexico boy feels bad for the dog. "I hope that she gets well. She is very playful."
Sometimes, the parents seem more excited than the children.
Maria Ocano snaps pictures of Piggy while her 14-year-old daughter, Maria Castro, is shy. The girl, from Mexico, has spinal muscular atrophy and is in a wheelchair.
Ocano likes that Piggy needs help getting around, too. "It's better for the child," she says. "The child see the dog have a disability."
Angel Lowery has to tell her daughter to stay in bed when Piggy rolls into Haley Champion's room. The 12-year-old from Denver has a neuromuscular disease and was at the hospital to be refitted for leg casts.
Mom and daughter talk about their own dogs. "He is so pretty," Haley says, thinking Piggy is a boy.
When Piggy was hit in November 2007, up to 90 percent of her spinal cord was severed. Hollingsworth was told she wouldn't regain any movement in her hind legs. Within days of the hit-and-run, Piggy had lost all muscle tone. She had no reflexes.
"It seemed like I would have to put her down," Hollingsworth said.
But she held off because it was the holidays. In January, Piggy stood on her back legs and her reflexes -- reacting when the bottom of her paws were touched -- started returning.
Euthanizing her never made sense to Hollingsworth. "I got her [from the pound] because I liked her personality and she keeps me company. And she still does that."
Today, Piggy can occasionally use her back legs. She goes to rehab, walking on a treadmill without her cart and balancing herself on an exercise ball. Hollingsworth has installed a wheelchair ramp for Piggy to get from her deck to the back yard.
She decided to train Piggy as a therapy dog based a reaction she got while walking Piggy around her neighborhood a couple of years ago. A man in a wheelchair, whose legs were amputated after a climbing accident, saw Piggy in her cart and started visiting her. He said she was one of the few things that made him happy.
"Just watching her keep going is just amazing," Scott Williams said in an interview with Hollingsworth through the oral history project StoryCorps on KCPW public radio. "She's like the coolest wheelchair individual in the United States."