I have never been a dog person. I like the idea of them well enough, but in the course of raising nine kids I'd never before made time in my life to know one well. We had plenty of pets, several dogs among them. Outdoor dogs, all rough and tumble, and only marginally domesticated. They always had more to do with the kids than they did with me, and that was just fine.

But now I wake up most mornings amazed to find a dog the size of a small pony milling around inside the house, greeting me with damp nose nuzzles and that happy skipping thing he does to tell me he's just as amazed to find me still here in his life. He's more than domesticated; he's downright civilized. He does not poop on the carpet, snarf food off the table, tug on his leash, growl at strangers or snap at small children who grab him by the ears and press enthusiastic kisses all over his hairy muzzle.

The explanation for all this courtly behavior has to do with his training: he is a service animal, individually trained from puppyhood to assist people with disabilities. Us, that is.

Well, maybe not all of us, though a disability is, by the very nature of love and caring, a shared experience. The dog actually belongs to Tony, one of our two still-at-home adult kids. Tony's autism response dog is Dude, a three-year-old golden retriever and poodle mix. I love this dog, but he has changed my life, and if I were not so shy I might even enjoy that part of the experience.

Dude was all Tony's idea. One evening at dinner our daughter Dara read us an article about a child with diabetes who was raising money for an alert dog. Until then we were unaware that dogs existed who could alert their person to dangerously high or low blood sugars—a situation Dara herself runs into often enough despite performing between ten and twelve blood tests daily on her calloused fingertips. How do dogs manage this remarkable feat? It has something to do with their sense of smell, though no one knows exactly what. A dog can be trained to detect a falling or rising blood sugar from clear across the room, day or night. Simply dumbfounding.

Tony, who rarely appears to be listening to our conversations, blurted an impassioned, "I wish they had autism dogs!" We all looked at him, glimpsing a firm jaw and fiery eyes before he ducked his head in surprise at his own unaccustomed outburst.

"What would an autism dog do?" I asked, struggling to draw a parallel between the physical effects of whacked-out blood sugars and the whimsical moods of autism.

"He'd help me get through crowds."

I pictured a large, friendly animal ambling with assurance through a maze of shoppers at a crowded mall, Tony beside him clutching a harness and striding with fresh confidence. Somehow I knew that was exactly what Tony was picturing.

As it turned out, my husband Bob could envision it too, and in short order we discovered that there are, in fact, service dogs trained to assist autistic children. Operative word: children. At nearly 30 years old, Tony didn't qualify. And anyway, these dogs actually work for the parents, helping control the child's wandering and obsessive behaviors. We were looking instead for a dog to guide Tony through crowds and calm him when his emotions threaten to overwhelm him.

It took two years to find a service dog with the right combination of skills for our needs, time I spent researching every conceivable aspect of service animal ownership. There was so much more to it than the basics of service dog etiquette that everyone is supposed to know—don't distract the dog or pepper its owner with questions. I learned what to say to the restaurant host who challenges our right to bring the dog in with us. How to keep both dog and gear clean and presentable on rainy days. Where he should lie on a crowded bus. What it takes to maintain his training. Even how to balance work and play for this very special animal. I began to worry that I might be headed for a late-life career change, from stay-at-home mom to service dog handler. I steeled myself with the knowledge that dogs have been cooperating with humans for millennia; hopefully Tony's dog would have inherited some of that doggie wisdom-of-the-ages, along with a good dose of patience for my stumbling efforts to appreciate the ways of the animal world.

Service dogs, I learned, are considered by law to be "assistive devices" which, like wheelchairs or walkers, must be accommodated in public venues. But dogs, unlike other Durable Medical Equipment, must meet standards of training and behavior as well. Fair enough.

Being a novice, I took to heart all the rules that applied to the handling of service animals, but none more than this one: A well-managed service dog should be invisible. The point of that strange dictum is that service dogs routinely go where no dog has gone before—or at least where nobody's pet dog is allowed: shopping malls, restaurants, grocery stores, classrooms, theaters, sports arenas. Because they're allowed this public access their behavior must be exemplary. Their bomb-proof demeanor should create no disturbances and render them effectively invisible to the watching world.

I can appreciate invisible. Throughout the years of raising our nine kids, ethnically diverse and differently-abled, we have attracted plenty of unsolicited attention. "Is this a day camp?" strangers would ask when we'd be out together. The fact of family was never obvious. Even now, with only Dara and Tony still at home, we still rate plenty of puzzled glances. Tony and Dara are black; my husband Bob and I are white. We are all adults, but of different generations. Tony's disabilities are obvious enough—the strange gait, odd commentary and obsessive hand movements—but his relationship to us is not.

Exceptionality of every kind is lonely. It separates people, sets them apart, and keeps them wondering how they will be accepted. Years of it have made me hungry for anonymity. With the promise of service dog obscurity, I dream of cool competence, controlling dog and son with a graceful choreography of smooth and subtle hand signals. No ruckus, no stares: invisible.

*    *    *

No amount of research could have prepared us for the reality of Dude's arrival. A large, energetic bundle of fur and personality is nothing like a wheelchair, no matter how the law may define it. Handling a service dog is not a job, it's a relationship, a mutuality of purpose despite our different species-driven agendas. Like any relationship, it's fraught with revelations about the other, some of them welcome, others demanding adaptations on both sides. It's also a logistics problem: fitting a dog this size into our spaces; finding the right mix of work and play to keep him motivated; learning to use cues to communicate with him and acquiring service dog gear to simplify our interactions in public.

The work of managing Dude is constant but light-handed, keeping his skills sharp by repetition, and offering encouragement quickly and consistently whenever he responds to our cues. He's an eager helper, unflappable, and more than happy to accompany his humans on excursions. He walks serenely beside me, ignoring Tony's sporadic tugs at his harness, rides calmly in cars and buses, and walks through grocery store aisles without sniffing the merchandise. He curls quietly out of the way under our table at restaurants and stays there for as long as we care to linger over our meal, the very essence of service dog obscurity.

But, invisible? Dude is an 85-pound mountain of golden curls, with soulful eyes that beg for contact. When, at my cue, he finally emerges from under our table, he is greeted by the startled gasps and stares of other diners who were unaware he was even there. So much for the theory that model doggie behavior can make us all blissfully inconspicuous.

A service dog is a presence. For one thing, it marks us as disabled, even when our disabilities themselves remain invisible. Strangers hail us from clear across the street to ask personal questions they would never dream of asking otherwise. At our crowded Starbucks, unasked, they yield the tables marked for people with disabilities. We thank them, send Dude to lie underneath, and slip gratefully into the roomy space. But I can't help feeling exposed, not only as a family with disabilities, but as a would-be handler who has failed at the basics of service-dog subterfuge. I can't even imagine what I was thinking when I dreamed of going unnoticed, blending seamlessly into the social scene.

Still, there's much about Dude that no one can see, even when it's happening right before their eyes. Who would guess when he nudges my leg with his nose that he's alerting me to Tony's heightening emotional state? If I miss that subtle signal he thumps his paws on Tony's shoulders and nuzzles in his neck, short-circuiting the escalating anxiety that would otherwise lead to a crisis. There is nothing invisible about a large dog leaping face-high on a grown man, but people react with amusement to what they assume is just an over-eager greeting from a big, goofy dog. No one sees the deeper purpose of preventing the panic, the uncontrollable shouting and flailing of a full-blown meltdown. In the nearly three years Dude has been with us, he has never been wrong about this, but there have been plenty of times I've ignored him, and regretted it.

Hardest of all for me has been learning to trust a dog to tell me what I myself cannot sense in my own child. Somehow Dude identifies subtle changes in Tony's mood that I, with all my years of mothering him, still cannot pick up. Is it the scent of some chemical change in Tony's body? I hug Tony firmly when he'll let me, and surreptitiously I sniff his neck, hoping to detect some hint of an aroma of anxiety. But if sometime in the distant past our ancestors had senses as keen as our dogs do now, it has all been lost.

Dude knows things I'll never comprehend, even distantly. I have no idea how he learned to sense an impending problem, nor why he decided to take such responsibility for it. Unlike me, he is not put off by Tony's rising emotional needs or his unreasoning behavior. To his canine mind it is not an interruption in the smooth functioning of any schedule, but simply the next thing that happens.

So I'm learning. Unfortunately, obscurity is never going to be my escape, but it is still my comfort. In the same way that Dude's mastering of the situation is invisible to the casual observer, so too are we. No one sees the struggle of our adult kids toward whatever independence they can manage. Or our efforts as parents to stand them on their own feet, not indulging the easy habits of unnecessary dependence. We are more than we seem, a mismatched set of generations, the younger ones slowly gaining life skills, the older pair gradually losing theirs to the processes of aging, but all of us still deeply engaged in the creation of a valid family.

It's the invisible part of what Dude gives us, his unconditional caring—no judgment, just intervention—that allows us to venture into the world together as a family. I comfort myself that my success as a service dog handler rests not so much on deflecting the public gaze as on the trust I've learned to place in our invisible dog.