Grade: A-

Christopher Guest sure does know how to breed mockumentaries. He was a driving force behind (and one of the stars of) the recently reissued classic “This Is Spinal Tap,” and in 1996 he and ex-Second City TV’s Eugene Levy, along with an adept crew of cohorts, gave us the deliriously funny “Waiting for Guffman” about putting on a small-town musical. Now he and Levy, as well as many of their compatriots from “Guffman,” turn their attention to dog shows, and the result, though predictably modest in both scope and execution, is about as joyous a treat as one could possibly wish for–a film that’s wittily observant while avoiding the mean-spiritness that such a subject might easily invite.

Concentrating, as “Guffman” did, on its characters’ obsessive pursuit of a seemingly silly goal, “Show” follows the trek of a variety of couples (and one single fellow) to the Mayflower Kennel Dog Show in Philadelphia, where they all hope that their pampered pet will take home the trophy. There’s hot-tempered Illinois yuppies Meg and Hamilton Swan (Parker Posey and Michael Hitchcock), whose hard-to-please Beatrice governs even their sex life; NYC gay hairdressers Scott and Stefan (John Michael Higgins and Michael McKean), who doll up one of their Shih-Tzus for the event; buxom gold-digger Sherri Ann Ward Cabot (Jennifer Coolidge), whose poodle is coached by professional handler Christy Cummings (Jane Lynch); ostentatiously middle class Floridians Gerry and Cookie Fleck (Levy and Catherine O’Hara), who dote on one another and their terrier Winky, about whom they write songs; and, on his own, southern fly-fishing store proprietor Harlan Pepper (Guest), who’s not only the proud pal of a handsome bloodhound but, as it turns out, a ventriloquist as well. All of the owners get into difficulties of one sort or another–the Swans lose Beatrice’s favorite squeezy toy, Scott and Stefan learn something unexpected about Sherri Ann and Christy (as do the women about themselves), and the Flecks find themselves housed for the duration in a hotel utility room–and all the performers get one or two exuberant scenes that will set you roaring. But among them the standout is certainly Levy, whose depiction of a man so dorky that he has a podriatric malady that must be seen to be believed is rich and continuously hilarious; the poor fellow’s equilibrium is further upset when, along the way, he learns that his wife is considerably more experienced, shall we say, than he ever imagined.

The other scene-stealer here is Fred Willard as moronic television host Buck Laughlin, whose stupidity is matched only by his obliviousness as he mouths nonsensical observations and queries while providing “color” commentary for his viewing audience; there are some wonderful reactions of incredulity from his British co-host Trevor Beckwith (Jim Piddock). There are also sharp brief turns from blankly serious Bob Balaban as the Mayflower president; Ed Begley, Jr., as a put-upon hotel employee; Larry Miller, as an old beau of Cookie’s who proves a singularly inept emergency negotiator; and Patrick Cranshaw as Sherri Ann’s barely sentient old hubby.

It can be argued that the target “Best in Show” aims at is an easy one to hit; that its scenario (created, no doubt, through lots of improvisation) is uneven, with some of the intercut stories not quite as amusing as others; and that, in many respects, it’s shamelessly derivative of the brilliant “Guffman” formula (down to the “six months later” epilogues that end the flick). But these are very minor quibbles about a picture that, in its wonderfully laid-back way, offers a marvelous stream of mirth. Guest’s “Show” effortlessly merges the sublime with the ridiculous, and in the process becomes an obvious blue-ribbon winner.