We've got enough lollipops for everybody," says Jamie Shaw, owner of the Dog School in Richmond. "And if it gets really tense in here, we'll all start singing 'Happy Birthday.'"

I'm sitting beside my mom and sister in a long, slope-roofed room that smells like dogs. Here in this strip mall, next door to Showtime Video, we're about to experience what Shaw calls "fight night." And we're already too tense for the lollipops to do much good.

It's our third session of a five-week class called "Dog Communication" -- "dog aggression" is an anthropomorphic way of seeing things, Shaw says. (My sister's local Humane Society in California had a way with names, too -- they called their course for barkers, biters and snarlers "Dogs with Attitude.") But aggression is what it's all about here, at least in our minds. All of us have dogs that don't play well with others. Many of us have had innocent walks that turned into tug-of-war sessions with foaming, snarling Cujos. And at least some of us have wondered whether it's our fault.

Tonight we're going to see what a dog fight is like when humans don't intervene. And just my luck, my dog is first.

Out in the parking lot, my sister and I open Sheila's cage and lead her out on a short leash. For the fight she'll need to be outfitted in Hannibal Lecter-gear, as she is every time we walk her -- first a red harness, then a basket-shaped greyhound muzzle that has to be eased on with a treat.

Lisa Barrett, one of Shaw's assistants, meets us at the door and checks the muzzle. "Oh, what a cutie," she says. Wagging her tail-stump, perking up her bat-ears, Sheila is a 20-inch-high Australian cattle dog with a strawberry-blond coat and brown eyes. Right now she's a good dog -- the dog the folks at the shelter were rooting for, the dog the vet's assistant wants to adopt. But Barrett, who has an aggressive dog of her own, is no fool. She tightens the muzzle several notches.

But not enough. When Sheila's opponent -- Luther, a lop-eared male shepherd mix -- appears at the far end of the ring, our dog ditches her muzzle in five seconds flat. Suddenly she's yelping and keening on the leash, trying desperately to get at Luther, her snapping teeth inches from Barrett's calf.

A time-out is called so Barrett can find a muzzle with a buckle a dog can't force off. Then Sheila emerges again -- just as frenetic as before, and just as indifferent to the treats we toss in an effort to distract her. Around the edges of the room, the other dog owners are sucking lollipops furiously. "Now drop the leash," says Shaw.

My sister obeys. So does her counterpart across the room. Both dogs surge forward -- the lanky 100-plus-pound shepherd and 48-pound Sheila, who's low to the ground and built like a tank, bred to challenge steer in the outback.

There are no preliminaries -- no sniffing, growling, jockeying for dominance. The dogs are locked together instantly -- their forelegs hugging each other's shoulders, their hind legs dancing back and forth for balance, their jaws snapping behind the muzzles. A single burring growl emanates from them, and I can't say whose counterpoint of high angry yelps I'm hearing.

After what feels like five minutes but is probably about 20 seconds, Shaw steps on Sheila's leash, ending this round. She points out that Luther, while still giving as good as he gets, is making efforts to retreat to the safe corner occupied by his owners. "He's had enough for now," she says.

Sheila has not had enough. Back in her corner, she deigns to eat some treats, but Luther's presence across the room is just too provocative. Soon she's keening and pulling again, drowning out Shaw's lecture. Upsetting as it all is, I can't help wondering -- did my dog win?

Maybe, maybe not. After Round Two, in which the dogs chest-hug each other like rival bears, Shaw announces her verdict, based on a reading of canine body language. Luther is "the more dominant dog," but "Sheila has the tenacity." I wonder if this is a nice way of saying that every fight for our dog is a fight to the death.

After watching an anticlimactic encounter between a romping Lab mix and a grouchy standard poodle, we pack Sheila back in the cage. "She'll sleep for the next two days," Shaw predicts. Sheila's eyes are red and swollen from the tight muzzle, but she still sits up and snaps at every car on the Interstate, her eyes wide and puppyish with glee.

How does an animal become the equivalent of a sociopath? Despite our quasi-parental feelings of responsibility, we know the truth: Sheila's problems go further back in her life than we do. We merely fell prey to the charm with which this dog woos human beings -- the licks and tail-wags and doleful eyes that helped her reach the age of 7 or 8 without meeting the common fate of unwanted pets.

Sheila's first owner's neglect landed her in a Northern California sheriff's office with a litter of pups, all more adoptable than their mother. The day before she was to be euthanized -- so the story goes -- the shelter attendants persuaded a young bricklayer from Ireland to take her. Badass barfly Sean liked having a badass dog -- until he found out that she could make him liable for other people's vet bills.

When my sister, who was Sean's neighbor in Oakland, met Sheila, she was already infamous for mauling a Dachshund and a Rottweiler. She was also affectionate to the point of clinginess, with a herding dog's Velcro tendencies. Many Frisbee throws later, Sean abdicated Sheila to my sister. They came East, Sheila snapping at cars all the way.

Like many owners of rescued dogs, we wonder fruitlessly about nature versus nurture -- did starvation and neglect make this dog a killer, or was it in her genes? Australian cattle dogs were bred from dingos, which may or may not eat babies. They have boundless energy and an urge to chase all critters, particularly small ones. So we keep the cat and the dog in separate rooms, and we walk Sheila with a short leash and a muzzle.

"It's all about maintenance, not 'curing' the dog," says Shaw, who also teaches in the University of Vermont's Department of Animal Science and runs a rescue service. While her controlled staging of dog fights may seem unorthodox, Shaw sees it as an exercise in owner education, one that may not help the dogs, but can't hurt them.

None of the other match-ups we see at Fight Night are anywhere near as fierce as Luther and Sheila's -- they involve a lot of what Shaw calls "communication," even if it's of the "You talkin' to me?" variety. By the end of the class, the testier dogs seem to have mellowed out -- all but Sheila, whom, with Shaw's blessing, we keep home on graduation night.

Shaw explains that most dogs aren't that gung-ho about fighting. "The normal pattern is to engage for 20 or 30 seconds, then separate, then maybe engage again, then get bored and engage in displacement behavior" -- for instance, pawing at the muzzle. Owners who understand their dog's dominance and aggression patterns will be able to exit a bad situation without panic -- something that never fails to incite the dog.

But Kevin Behan, author of the book Natural Dog Train- ing, thinks "fight nights" do more harm than good. "I don't like muzzles -- it's like handcuffing children. It just makes the situation more intense," says the Newfane trainer. He thinks the key to handling dog aggression is to get dogs to open up to and trust one another, using their innate "incredible compulsion to be social."

Whereas Shaw teaches owners to desensitize their dogs to provoking stimuli -- or learn to avoid them -- Behan argues that dogs need to be "resensualized." "Don't focus on the noise, the angst, the terror," he says. "When your dog's attacking another dog, she thinks that dog is the most important thing in the world. Focus on that attraction and make it more supple."

Does Sheila need to be desensitized or resensualized? Will her primal dingo nature get in the way? Thought-provoking as these questions are, they pale in comparison to practical issues such as: How do you walk a dog that attacks everything on four legs?

Although most local towns have leash laws on the books, most dog-owners ignore them. I know -- I used to walk a roommate's collie-mix puppy on the South Burlington bike path. The puppy came when called, so I let her romp free and accost other, more sedate dogs. I remember an owner once calling out nervously "Is she OK?" as my dog crouched and then sprang up, tail wagging furiously in mock-attack. She was just playing -- it seemed so obvious. How, I wondered, could such a joyful dog make anyone anxious?

Today I have to call out to folks on the bike path, "Can you leash your dog, please? Mine's not good with other dogs." Then I grab whining, wriggling, pulling Sheila and run as quickly as possible in the opposite direction, hoping the exuberant puppy won't catch up.

It's a humiliating experience, though if the fight nights have done one thing for us "difficult dog" owners, they've shown us that we're not alone. "It's very isolating to own a dog with aggression issues," Shaw told us on the first night of class, likening the room's atmosphere to that of a 12-step meeting. ("My name is ___, and my dog attacks other dogs.") We share fears of lawsuits and frustration with the off-leash crowd, though we'd like nothing better than to join them.

We also seem to have our own version of the Serenity Prayer. It involves giving up certain dreams -- a stroll down the canine gauntlet of Church Street, a bracing off-leash hike -- and accepting our dogs as the loyal, loving, predatory, demanding, not-always-cuddly companions they are. "Our society has the expectation that all dogs are supposed to be like Lassie or Rin Tin Tin," says Shaw. "But that would be like saying to a person, 'I would like you to be happy for the rest of your life.'"