It brings Jessica Kensky joy to watch her dog run.
At the park, Rescue the black Labrador chases balls down and leaps with athletic abandon.
He came into Kensky ’s life six months after the Boston Marathon bombing.
Kensky , now 35, and her husband, Patrick Downes, 33, each lost their left leg below the knee as a result of the attack. Rescue, her service dog, is her favorite subject — and a reason to get up in the morning. His large head and heavy jowls made her laugh for what seemed like the first time in years. The day he came home with the couple in September 2013, Kensky actually slept through the night for the first time since the bombing.
During the dark moments, Kensky takes Rescue to the park. She watches him do what she no longer can.
And now, Kensky and Rescue’s story is the inspiration for a children’s book scheduled to be released in spring 2018 by Somerville’s Candlewick Press. It is the story of a girl and her dog. It doesn’t mention the bombing.
“It is very much a partnership,” Kensky said. “He’s very intuitive, and he does know when I’m upset and when I’m sad and when I’m happy and when I’m playful. I just think he totally picks up on your mood, and he did that from the very beginning.”
While she was still bedridden in the hospital, Kensky applied for a service dog from NEADS —National Education for Assistance Dog Services — in Princeton.
At that time, Rescue, at all of 8 weeks old, was wandering through a maze with other puppies, all of them undergoing training.
There’s a test all those puppies are given. If they lead, they have the makings of a solid seeing-eye dog.
Rescue was a follower. A good service dog needs to know how to take instruction.
The connection between Kensky and Rescue was magical, said Cathy Zemaitis, director of development for NEADS. He was the laid-back canine that occasionally wore pads because he flopped down on the floor so often. He sniffed Kensky’s food and looked up with big, soulful brown eyes.
“We were all so gratified by the instant connection that they had,” Zemaitis said. “We knew from the get-go that was the right match. . . . Rescue is a sensitive soul.”
Kensky “fulfills things that he needs, and he fulfills things that she needs.”
It was, Kensky and Downes knew, a love story that deserved to be told. They talked about writing a book over dinner two years ago with a friend Clelia Gore, who happens to be a literary agent. She helped write their story.
“They’re still facing, especially Jessica, a lot of hardship and struggle,” Gore said. “Every time they get to work on this book, it brings them so much joy.”
In the 32-page book, “Rescue and Jessica,’’ the protagonist is a young girl named Jessica. She’s trying to adjust to life with prosthetics, wheelchairs, and crutches. A senior editor with Candlewick, Katie Cunningham, said she wanted the book to demystify what it meant to live with a disability.
“Like what a limb might look like under a prosthetic, or how a variety of adaptive equipment could be used, or exactly what a service animal does,” Cunningham wrote in an e-mail. “But my most fervent hope for this book is that it will be a mirror. I want a child who sees her experience reflected in this book to know that we, as a world, see her.”
Tuesday, Kensky and Downes sat down with illustrator Scott Magoon, who presented them with sketches. Most of their feedback was trained on the images of Rescue.
“His jowls are not big enough. On every page I was like, ‘Bigger jowls, bigger jowls,’ ” Kensky said, laughing. “Bigger head. Because I think that’s what makes Rescue, Rescue.”
Magoon ran in the Boston Marathon the year of the bombing. The blasts went off in front of him and several feet behind him. He’d been searching for years for a way to use his art and make something positive out of such a terrible day. The book is set in Boston.
“I really wanted to show the relationship between Rescue and Jessica,” Magoon said, “to create the warmth and connection there.”
It’s the warmth of a pet owner who relies on her dog to stand and brace her if she falls. He can fetch her phone or prosthetic limb or bark if she needs help.
If Kensky sneezes, Rescue grabs a tissue. If Kensky is cold, he brings a blanket. The big black Lab has been there through so many chapters of Kensky’s story, including when her surviving leg had to be amputated.
It’s not over yet. There is another surgery scheduled before the end of the year.
Rescue will be there by her side. Pillows in their Cambridge apartment express how they live: “All you need is love . . . and a dog.”