It’s a mellow December Tuesday afternoon, and Bella, a 40-pound whippet-lab-terrier recipe for canine greatness, emerges from owner Jean Baur’s car in the Mystic Middle School parking lot. Bella instantly sets off across a grassy lawn in front of the building with the eager confidence and certainty of a high-paid Sherpa ascending a familiar peak.

It’s a regular stop for Baur and Bella — one of several they make each month to hospitals, rehab facilities and schools doing volunteer work. Inside the building, administrators, faculty and students greet Bella happily and, over the course of the next half-hour, with Baur’s gentle guidance, the dog interacts in delightful fashion with a small group of eighth graders — all of whom clearly regard the visit as a weekly high point.

Patients, pupils and retirement home residents who regularly look forward to seeing Bella may not know it, but the 10-year-old dog is the co-star of a new book. “Joy Unleashed — the Story of Bella, the Unlikely Therapy Dog,” written by Baur, hit bookstores in August from New York’s Skyhorse Publishing. On Saturday, from 11 a.m. to 2 p.m., Bella and Baur (who is also a public speaker) will appear in Westerly’s The Elms assisted living facility. The event is open to the public, and copies of “Joy Unleashed” will be available for purchase — and, yes, readers can get their books signed or affixed with a paw print.

In the early days after Baur and her husband, Bob, adopted Bella from a litter of puppies found by an animal rescue group on Dead Dog Beach in Puerto Rico, the canine gave little indication she’d be remotely suited for therapy dog duty. In fact, Bella’s persona was a lot more “Marley” than “Rin Tin Tin.”

“Bella was a crazy puppy,” Baur says as she sits in the living room of the family’s Stonington home. Bella watches her every move from the couch while a handsome cat, Henry, purrs on Baur’s lap.

“She was so wild. When we first got her, we were living in Pennsylvania, and we had to keep her on a leash inside the house! She would crash into furniture and chase Henry, and she ate anything she could get her paws on — my sandals, a pillow, the cover off the bed ... And the backyard looked like the moon.”

Bella’s transformation started soon thereafter and continued over the next few years through a series of obedience and agility classes before the family vet, pondering the ongoing behavioral disorders, told Baur, “You know what that dog needs? A job!”

That remark resonated with Baur when a friend said she was evaluating whether her own hound could work as a therapy dog. Baur decided to give it a shot. With more training, classes and practice, Bella was indeed awarded her therapy dog certification in the fall of 2011 — and when Baur suddenly lost her own job a few months later, it was ultimately a fortuitous development.

“I was dreading the first of the year, when I’d have to find something to do,” Baur says. “But that’s when Bella and I started visiting hospitals — and it was this amazing lifeline that was new and interesting and challenging.”

Baur says, for example, that she’d never spent much time in hospitals, and learning the culture and the rhythms, procedures and routines therein was intimidating. But, over time, she and Bella became acclimated and grew comfortable and began to relish the therapy experiences. And they got better at it. The patients were receptive, and Baur says an unexpected benefit was seeing how much Bella buoyed the spirits of hospital staff members.

“One of the lessons I’ve learned from Bella is really just to get out of her way and trust her instincts,” Baur says. “Dogs know when you’re sick or sad, and their whole being is about cheering you up.”

At the same time, Baur thoroughly enjoys the teamwork aspect. “I used to jokingly call myself Bella’s chauffeur. But it really is both of us — who I am and how I interact with people is part of it, and who Bella is and how she interacts is the other part. And, in the book, I really just wanted to show what I call the everyday miracles — what happens when you let dogs be dogs.”

In 2012, the Baurs moved to Stonington, and the therapy work expanded to schools. Baur says Bella loves every opportunity to be with the people they visit but particularly loves children.

“Oh, the kids are her puppies. She just prances down school hallways and looks for any classroom doorway. She’s like, ‘Hey, I’m here! Wanna see me?’” she says.

Greg Keith, principal at Mystic Middle School, says he’s completely sold on therapy dogs and the benefits they provide.

“We like any opportunity to let kids learn about acceptance — whether that’s animals or people or students with special needs. Seeing humans and animals being naturally accepting, that’s a powerful and motivating thing,” he says.

Working with a therapy dog is incredibly rewarding, but it can take an emotional toll, as well.

“Yes, there’s sadness and loss and the difficulty of some of the work, and there are certainly times when it’s just hard — for both of us,” Baur says. “And my most important job is to protect Bella. You have to make sure the dog isn’t getting overwhelmed. Bella has these funny little creases on her face that show up when she’s tired or stressed.”

As for writing “Joy Unleashed,” Baur says she’d been reading books about therapy dogs since she and Bella aimed for certification. A lifelong diarist who’d been detailing Bella’s experiences and exploits, Baur is also the author of two published titles in the professional careers field. When she noticed the therapy dog books seemed to fall into either very clinical tomes or decidedly more anecdotal, Baur wondered if she could write something that would land somewhere between.

“I did think there was a void and (the literature on dog therapy) could use some deep, personal stories. Writing a book on the subject seemed a natural extension to me,” she says, “and a lot of what I was reading disappointed me because I didn’t think they showed what these animals can do.”

Though she’s had literary agents in the past, Baur, for this project, went straight to an editor. Incredibly impressed by a dog book called “Rescuing Riley, Saving Myself” by Zachary Anderegg, Baur found the editor’s name in the acknowledgments and started a barrage of cold-calls.

“That’s who I’m going after,” Baur remembers saying to herself. She laughs. “I’m not a stalker, but I’m awfully close. I think she agreed to look at the manuscript just so I’d stop bothering her. I’m glad she did. I think she liked the story.

"So many people told us Bella wouldn’t make it as a therapy dog. But she did.”

IF YOU GO

Who: Jean Baur and Bella

What: Discussing and signing copies of “Joy Unleashed — The Story of Bella, the Unlikely Therapy Dog”

When: 11 a.m.-2 p.m.

Where: The Elms Retirement Residence, 22 Elm St., Westerly

How much: Free and open to public, books available for purchase

More info: (401) 596-4630