Across the park Ortiz spots a squirrel and chases after it, bounding through the overgrown grass.

“Ortiz!” I call, and he stops on the spot. Part beagle, part rat terrier, he comes back to me, his pink tongue pushed forward between his teeth.

“Good boy,” I say, kissing his head, the squirrel now safely up a tree. He can wait out squirrels for as long as need be, but today we cannot linger. I’m finally healthy enough to do some volunteer work and need to be there within the hour.

“Come on, buddy,” I say, saddened to pull him away from his hunt. He hesitates, eyeing the squirrel, who taunts him from a low branch. Then he follows me.

We walk to the edge of the Huron River in Ypsilanti, Michigan. For years I was unable to take long walks like this, as the jangled neural pathways of my brain couldn’t retrace my steps back home. I kneel and clip the leash on his bright-red collar, which is carefully stitched with my phone number. Ortiz licks my face. We touch foreheads. What would I do without him?

Later, when I take him home to my neighbors’ house, he tries to leave with me, as he often does. Sometimes it’s a struggle to get him to stay there. Part of me believes Ortiz loves me more than he does his family. The other part of me thinks I’m reading too much into the situation. And that’s the safer voice to listen to, because, at the end of the day, he’s not my dog.

 

Before I moved here, I lived in New York City for twenty-five years. I wrote about music and boxed and traveled and ate out and went dancing till the sun rose and snuck into the dog run at Tompkins Square Park even though I didn’t have a dog. I was married to a rock musician, and we ducked under the velvet ropes of any club we visited. Most days I couldn’t walk out my door without bumping into at least one person I knew. It was a good life.

But one day I was working in a furniture showroom, and a heavy wooden tabletop mounted on a wall snapped its rope and fell on my head. The ensuing pain was debilitating. I followed the advice of a sports doctor who worked for the Knicks and the Yankees, and the pain subsided. Then it came back. For years it came and went. For months at a time, I woke up with it and went to bed with it. Each time it left, I assumed I was finally better.

During one of my pain-free stretches, I decided to move back to Michigan to be closer to my parents. They had just turned eighty, and my mother’s health wasn’t great. And the New York I knew was changing. My beloved Lower East Side had been taken over by a new breed of New Yorkers. Gleaming glass high-rises with rooftop pools rose from previously empty lots below Houston Street. All day construction workers hammered and yelled, and at night the streets filled with the buzz of drunken youth stumbling between trendy bars. I could have simply moved to Brooklyn, but my cats deserved better than an expensive patch of grass on a roof.

So, several years after the tabletop fell on me, I bought a modest bungalow on a tree-lined street in Ypsilanti. I started teaching twice a week and taking long, daily walks: To the south was a historic neighborhood and a park on the Huron River. To the northwest was a wide and rolling graveyard that reminded me of Central Park, only with headstones.

But the pain returned. With it came a bevy of symptoms: tingling in my hands and feet, vertigo, a racing heart, the thick, heavy sensation of being underwater, severe memory loss, and the kind of insomnia that kept me awake for three or four days straight.

Within a year of my move, going on walks became nearly impossible; I couldn’t even find my way home from the next street over.

 

I visited general practitioners; orthopedists; ear, nose, and throat specialists; and neurologists at the University of Michigan hospital, carefully telling each of them my symptoms. I saw another sports doctor, who acknowledged that what I was experiencing was a result of my head injury. He advised me to adjust to what was happening, because in a year I’d probably be worse. “After head injuries,” he said, “the body slowly unravels.”

Finally I found a chiropractor who figured out that my head was on crooked and my brain wasn’t getting enough oxygen. I got some relief from his adjustments. It wasn’t enough. My father moved in with me for three months to help out, but he had to return to his own life with my mother forty-five minutes away.

Amid all this, I continued to teach at the local community college. In the classroom I couldn’t remember what students had just read out loud. My heart raced. I was exhausted. I’d forget how I’d gotten to work or how I was getting home, and I’d fight the desire to stop class and ask if someone was driving me. I didn’t tell anyone in my department what was happening, for fear I’d be fired.

My dad arranged to drive me to school on Tuesdays and Thursdays. Other than those two days, I didn’t see another human being all week. I lived with three cats: Lulu, Hank, and Clementine. There was rarely a moment one of them wasn’t snuggled on my lap, strutting over my keyboard, or wrapped about my neck. But even with their love, the isolation was blistering. My Michigan pals didn’t live close by, and I didn’t want to drag new friends into my suffering. Casual acquaintances fell away like acorns from a tree.

Then a friend told me about Dr. Lu, who’d been trained by healing monks in China. He said that the reduction in oxygen to my brain had caused complications throughout my body. I didn’t completely understand his diagnosis, but under his care I began to improve. The crushing head pain was gone within weeks. My heart stopped racing. I was hopeful that I’d be well soon.

But the vertigo continued, as did the memory issues, the insomnia, and the underwater sensation. My days were still hard. I was still scared. Other than teaching, the occasional visitor, and my cats, I was still alone.

Into this comes Ortiz.

 

It’s been two and a half years since I fell ill. A young couple in their thirties rents the house across the street: Jessica’s studying to be a doctor; Rick, a social worker. Jessica and I periodically take walks together. Her small dog, Ortiz, sometimes joins us. He spends his days eating shoes, peeing on the carpet, and jumping the backyard fence. But no matter where we go, I notice that he always knows the way home.

When Jessica becomes pregnant with her first child, our walks stop. I miss them, but I still can’t walk on my own. The last time I tried, I got lost in the graveyard. So after a few weeks I ask Jessica and Rick if I can walk Ortiz. They say yes.

Our first walk is around the block. Ortiz nearly chokes himself as he tugs me forward, reminding me of the sled-pulling dog in How the Grinch Stole Christmas! He doesn’t listen to a word I say, doesn’t seem that fond of me, yet when I appear at his door the next morning, he practically somersaults in greeting. This time we venture around the neighborhood, Ortiz pulling me into the sunshine. It’s a delight being outside with him — birds singing above my head, the smell of the nearby river.

After a week we cross into bordering neighborhoods. We walk like New Yorkers; I’m thrilled to discover I haven’t lost my stride. My back straightens, my hips loosen, and my lungs expand. Before long we’re walking an hour a day, sometimes two, in heat waves, rainstorms, and blizzards. I pick up Ortiz each morning, and we spend twelve hours together, both outside and at my house. I love the sweet, earthy smell of him; the exuberant wiggle of his butt as he dashes down the stairs; the clack of his nails on the floor as he follows me from room to room before curling up next to me.

There are still mornings when I feel no purpose to my life, but walking Ortiz is making me healthier, which is good: I have to get healthier to keep walking Ortiz.

We’re regular visitors to the graveyard, where I let Ortiz off the leash, and he disappears among the firs and oaks. Trying to find him becomes a game. He’s a distant blur between tombs as I stand on the tallest hill, squinting into the light. I feel like a tracker, learning to follow the jingle of the tags on his collar, the faint outline of his prints in the mud and snow. I wonder if these exercises are reestablishing some of the broken neural pathways in my brain. When Ortiz returns, his joy lights something inside of me that had grown terrifyingly dim.

 

Eventually we’re kicked out of the cemetery after Ortiz runs through a funeral: signs pop up saying dogs must be kept on a leash. Ortiz’s collar has become threadbare, so I order him a new one with his name and my phone number stitched into it. Rick and Jessica think this makes sense, since he spends most of his time with me. It also comes in handy because I often forget my number.

We begin frequenting the park nestled in the curve of the river. My connection to nature deepens. I learn that the days my head feels heavy with pressure are the same days the river runs hard and fast. Sometimes we rest inside a thicket of maples; other times Ortiz throws himself into the woods until I can no longer see him, but he always comes back.

Everywhere we turn, it seems, there’s another off-leash dog, and Ortiz befriends them all. He runs in circles with them while I stand with the other humans. We’re like the parents of preschoolers — full of worry and pride.

How ordinary this is: being outside, chatting with friendly strangers, my house nowhere in sight. And yet how extraordinary. For so many years most of my conversations with other people have revolved around my health and taken place in my living room.

In the beginning I make sure to tell people that Ortiz isn’t my dog. Then one day by the river an older woman approaches and says, “I’ve been watching the two of you, and that’s some kind of love.”

Ortiz looks up at me, his tongue hanging from the side of his mouth. And I realize that in some way he is my dog.

 

With Ortiz by my side, I continue to get better. I visit the farmers’ market, venture down streets I’ve avoided, and run errands that previously seemed impossible. Ortiz tugs me into stores and makes friends: the women at the barbershop who give Ortiz his daily treat; the shoe salesman with the easy laugh who gives him his other daily treat; the gray-haired husband and wife who let Ortiz romp with their dog along the winding brick paths of their English garden.

I grow more confident, more capable. There’s color in my cheeks. I sleep better, laugh more, push myself harder, worry less. My family, friends, and doctors notice the changes. I return to volunteering, take on more editing work, start to pay attention to the world around me. And Ortiz stops running wild. Fellow dog-walkers begin to tell me what a well-trained dog he is. But I’ve never trained him.

Ortiz is good at reading me, and on my more difficult days he stays close. But one morning, when the damp weather fogs my brain after a sleepless night, I release his leash in the park, and he shoots up the wooded hill that leads to the road. I’ve never seen him in such a state. I bolt after him, searching the woods that separate the park from the road, calling and calling, fear growing in me. No Ortiz. I climb the hill and study the street. Nothing. I head back down and call him again, my heart thumping. Ten, fifteen, twenty minutes pass. Finally he returns. I don’t know whether to hug him or scold him.

As we head out of the park, Ortiz now on a leash, a woman stops us, her eyes wide.

“Oh, you’re safe,” she says with a sigh, bending forward to pet Ortiz. “I saw him running frantically up the hill and then along the road. It was clear to me he was looking for help.”

 

During our third winter together Michigan is submerged in a near-constant blizzard with more than a hundred days of below-zero temperatures. Ortiz and I walk them all. I purchase arctic gear for both of us, and we trudge to the park, making our way over icy sidewalks and through high snowdrifts. No one else is out in such shocking cold, so there are no paths. We forge our own, then forge new ones the next day because the snow never stops falling. Ortiz bounces over the drifts like a rabbit. I slog through, my body wet with sweat beneath my layers of gear. Muscles I feared had grown dormant start firing up.

Every day we walk in the snow, the trees bare, my cheeks frozen, my boots squeaking. Ortiz is snug in his red tartan coat, and the shades are pulled on the homes we pass. The streets belong to us.

 

Spring arrives. Jessica will be finished with her residency and Rick with his schooling in just over a year. The closer Ortiz and I grow, the more their inevitable move looms over me. Now that Jessica’s job offers roll in, I am forced to acknowledge there is an end date. There has been all along.

Each time Jessica and Rick travel, I take care of Ortiz. My cats have grown to love him. Everyone in my life knows him. He’s my first posting on Instagram and is all over my Facebook feed. My dad jokes that he’ll meet me in the park when I take Ortiz for his final walk, and together we’ll sneak the dog into his car; I can tell Jessica and Rick that Ortiz ran away. Rick twice says that he and Jessica have talked about leaving Ortiz with me, and he’s explained to their vet that “Ortiz is Jane’s dog, too.” I hang on to this, but I’m already feeling the hollow of his loss.

In July, during Ortiz’s routine dash from his house to mine, I hear a car approaching. I’m not sure he’s going to make it safely across. In that split second I have a choice: call out his name and possibly cause him to stop midstreet and get hit, or just hope he makes it across. I choose to stay quiet.

Ortiz disappears under the front wheel of a speeding SUV. His agonized yelps bring out the neighbors. I run to him, and he looks at me, eyes wide with distress. When I bend to scoop him up, he bites my hand hard enough to draw blood. I am grateful. It means he’s alive.

One neighbor helps get him in the car, and another drives us. I hold Ortiz in the back seat, kissing his head — his body wrapped in a blanket, my hand in a dish towel. I call Rick and Jessica to let them know what’s going on. When we reach the vet, I hustle Ortiz inside.

Before I can even explain, the vet tech whisks him to the operating room and leaves me to fill out the paperwork. Because I’m the one who brought Ortiz in, they want me to use my name and address. I feel as if I’m at last officially claiming him as my own. When Jessica arrives, having left rotations at the hospital, I apologize for putting my name on the paperwork, but she doesn’t seem to mind.

My hand is still throbbing and bleeding; everyone thinks I should go to the hospital, but I don’t want to leave Ortiz. Finally they convince me, and another neighbor drives me there. A nurse X-rays my hand, cleans the wounds, and gives me a tetanus shot.

When I return home, I run to Ortiz’s house. His body is swollen to the size of a basketball, and he has a cone around his head. Though he’s clearly drugged, he wobbles over to greet me, tail wagging. I drop to my knees and put my forehead to his. Jessica is there, tears in her eyes.

“I’m so sorry,” I say over and again.

“It’s OK,” she says.

Despite his injuries, somehow Ortiz has no broken bones. I erase everything from my calendar and pick him up at seven each morning, carrying his drugged body up the stairs to my couch or to the soft grass of my backyard, where I sit with him until seven at night. I try to get him walking — painstakingly slow circles in the backyard.

His recovery is quick. By the end of the week, we’ve returned to the park.

 

The move date is set: August 15, 2015 — almost four years to the day after I began walking Ortiz. In the weeks leading up to their departure, my anxiety mounts. I wait for Rick and Jessica to say they’ve decided to leave Ortiz with me, but they don’t. Less than a month before their move, I gather my courage and ask Rick if they’ll consider letting Ortiz stay. He says he’ll speak with Jessica about it. The next day I receive an e-mail kindly explaining that they can’t leave him. “You have been so good to him,” Rick writes. “His time in Michigan has been full of love.”

What is there to say? I’ve been lucky to tend to him for four years. And now he’s going on with his life, and I’m staying here with mine.

In our last week together I cook Ortiz chicken and give him especially attentive rubs. We go on extra-long walks, even returning to the graveyard — the signs have been taken down, so I let him off the leash, but he barely leaves my side. I hold him close and tell him about the big backyard at his new home. And every night after I drop him off, I weep.

We take our last walk on a muggy day, my heart cracking. Does he understand? Does he know this is goodbye? When we get home, I sit on my couch and hold him, whispering reassurances into his ear. Rick and Jessica knock on my door. I hold out desperate hope that they’ve changed their minds. They haven’t.

I clasp Ortiz’s leash onto his collar for the last time and follow Rick as he walks him down the street to the van. Ortiz looks back at me, his eyes big, and pulls against his collar. Rick nudges him in and closes the door, and Ortiz jumps up on the front seat, makes nervous lip-smacking noises, and stares at me through the open window.

Isn’t it clear he wants to stay? Do they not see his distress? Or am I imagining it? “If anything changes . . . ,” I say. They both nod. They feel bad, but Ortiz is part of their family. I kiss his snout and weep so hard that their little girl, now nearly four, asks her dad what’s wrong with my face.

“She’s sad,” he explains.

I touch Ortiz’s head one last time, and then they drive away.

 

After Ortiz leaves, I think I might go mad with grief. The cats pile on top of me. Friends try to comfort me. No one can believe he’s gone. Rick and Jessica text me pictures of him in his new backyard, alone. I wonder if he’s wondering where I am. They think he looks happy. I think he looks depressed.

Several months later Kalie, Rick and Jessica’s former nanny, shows up on my doorstep. She says she saw what I did with Ortiz. She asks if I’ll walk her dog. So I start walking Dip. It helps. Then Kalie fosters Delilah, so I walk her, too.

Delilah is a bighearted beagle mix; one day I bring her home, and my cats waltz right up to her and rub their heads against hers. Then she curls up on the couch with me while I work. I gaze down at her. “I think you’re supposed to live here,” I say, surprising myself. I’m unsure if I’ll be able to love her the way I did Ortiz.

But it doesn’t have to be the same. Exactly one year after they move — the same week I adopt Delilah — Rick and Jessica get a second dog. The texts they send now show Ortiz and Penny running in happy circles. I snap on Delilah’s leash and kiss her head, and we set out on our own walks. As it turns out, the heart can hold both love and grief. I’m still not fully well, but I’m no longer hanging on by the tiniest, thinnest thread, a thread that Ortiz got between his teeth and tugged on gently and persistently until I landed back in the world.