Every dog has his day. And this Saturday will be a red letter one for local show-quality dogs at Bull Run Regional Park, site of the 84th Dog Show and Obedience Trial of the Old Dominion Kennel Club.

Like dogs, dog shows come in all shapes and sizes. But Old Dominion is special: everyone exhibits at Old Dominion. In 1983 more than 3,000 dogs competed in the show, making it the largest dog show in the country that year. In 1984, only the gala Centennial Anniversary Show of the American Kennel Club drew more entries. More than 4,000 dogs representing 128 breeds are expected to compete in Saturday's events in front of 53 judges whose task it is to pick the top dog.

If you've never been to a dog show, you're in for a treat. Unlike many other sporting events, you don't have to memorize the rule book to enjoy the competition. In addition to watching the judging, you can browse the concession booths for goodies for your own dog, or seek realistic advice about dog matters from exhibitors and breeders who have decades of experience. The people-watching isn't bad either. You may even be able to get the definitive answer to that age-old question: Do owners really look like their dogs?

A few things to keep in mind for the show:

"Never approach or touch a dog," cautions JoAnn Redditt, a veteran dog show exhibitor. Most show dogs have been trained to be handled by people, but you never know. "Dog owners are more likely to bark at you than their animals are to bite. People are very particular about their show dogs," adds Redditt.

As for creature comforts, be sure to take lawn chairs or a blanket, since few shows provide any type of seating arrangements. Also, be sure to wear comfortable shoes that can withstand a trek through the mud, or a misplaced step into a spot that the clean-up crew has yet to scoop.

Once at the show site you may be surprised by the buzz of activity -- there are a lot of dog show enthusiasts. In the exhibitor's parking area you'll see everything from tiny imports to huge recreational vehicles that have been specially outfitted to transport dogs and gear. Small canopies will be shading puppy exercise pens, statue-still dogs will be receiving last- minute touch-ups on grooming tables, and nervous handlers will be pacing or puffing on cigarettes.

To best understand who's who and what's going on at the show, you should invest $4 in a catalogue, which will give you information about the judges, the dogs and the exhibitors. The name and address of each owner are included in the catalogue, so if a particular dog steals your heart, you can contact the owner about future breeding plans or the availability of puppies. Normally the dogs being shown are not for sale.

With your catalogue in hand, you can survey the judging program and decide which events you'd like to see. The Old Dominion show is quite spread out, so the catalogue includes a map to help you find your way to the rings.

Along the way you may want to stop and shop in some of the concessions. With more than 40 merchants participating, the Old Dominion Show is a premiere doggie shopping event. You can find virtually everything for dogs and their people -- books, vitamins, grooming supplies, T-shirts, stained glass items and much more. Everything is usually priced well below what you'd pay for the same item in a store. It's a great opportunity to stock up on gifts for dog lovers.

If you're thinking about buying a pure bred dog, there's no place like a dog show for fact finding. Whether you're just beginning your search and are interested in learning a little bit about a number of breeds, or if you know what breed you want and are seeking specific information about bloodlines, the people at shows can tell you what you want to know.

On the whole, people who own show-quality dogs truly enjoy the animals and are more than willing to share their knowledge. But don't try to talk to them while their breed is being judged -- you'll probably get the cold shoulder. The best time to talk to exhibitors is after the judging, when the dogs are back in their crates and the people have recovered from the stress of the ring.

After a walk around the show grounds, you'll be ready to relax at ringside.

Who are these people and dogs you'll be seeing in the ring? Dog fanciers are a diverse lot, and while the hobby isn't cheap, you needn't be a millionaire to compete. While many exhibitors have very average incomes, they've made a decision to devote a large part of their income to showing dogs -- from an annual bare minimum of $1,000 to as much as $200,000 for one dog. And the money is only the tip of the iceberg.

"Spectators think that dog showing is an easy sport," says Carlos Mejias, owner of the Olde Towne School for Dogs in Alexandria. "But there's a lot more to it than just holding a piece of liver in front of the dog's face to get him to stand correctly. From the age of eight weeks, show-quality puppies are trained to 'stack' or pose in the show stance. Many hours of training go into teaching the dog how to move while on a lead. To look that beautiful takes a lot of time, patience and money. It's not all second nature."

While many of the exhibitors are average people, the dogs are strictly upper crust. To be eligible to compete in Championship Point Shows of the American Kennel Club, a dog must be pure bred and registered with the AKC. Breeders and owners exhibit their animals at these events to publicly display their success in breeding quality dogs.

Dog show judges are certified by the AKC, which establishes a "standard," a detailed description of the perfect specimen, for each breed. Ideal size, weight, color, coat, movement, intelligence and temperament are covered in the standard.

Judges have to evaluate each dog according to the standard. Needless to say, perfect dogs, like perfect people, are few and far between, so judges must carefully weigh faults against good points. The plot thickens when you add the fact that judges, too, are only human, and a certain degree of their own personal taste can't help but seep into the judging process.

The subjectivity of the judges makes the sport flukey. "Chicken one day, soup the next," says Kate Berman, a talented teen-age exhibitor from Potomac. At a show last spring, Berman's Irish Setter defeated 80 others of his breed. The next day, a judge at another show failed to give the dog a second glance.

At a large show like Old Dominion, judging for ten or twelve breeds will take place concurrently. But for each breed, the order for judging will follow an established pattern. All entries are judged in groups called classes. In dog show lingo, male animals are called dogs, and (don't be offended)females are referred to as bitches. Dogs always are judged first, bitches second.

A final ord of caution: dog shows can be habit forming. Many a dog fancier has been hooked after just one show. But there's always room for more competition.

PUTTING ON THE DOGS

The Old Dominion Kennel Club's 84th Dog Show and Obedience Trial takes place this Saturday in Bull Run Regional Park in Centreville. Show grounds open at 8 with judging scheduled to begin at 9, and winds down in the late afternoon. Admission is $2 adults, 50 cents children. The park is at 7700 Bull Run Drive. To get there, take I-66 West to the Centreville exit and go west on U.S.29-211 to a left on Route 621 to the park entrance. Keep an eye out for the blue and white dog show signs. For more information, contact the Show Chairman, Garland Bell, 703/620-4818.