Doggy Breath Is No Obstacle To This Love Affair

Sylvia

Comedy by A.R. Gurney. Starring Charles Kimbrough, Blythe Danner, and Sarah Jessica Parker. At Manhattan Theatre Club.

LET'S just get the cliched phrase out of the way at the beginning: A. R. Gurney is going to the dogs. That's exactly what he does in this ''romantic comedy,'' which is about the love affair that occurs between a man and ... his dog.

Greg (Charles Kimbrough) has long been happily married, his kids are off at college, and he makes an excellent living. His beautiful and smart wife Kate (Blythe Danner) has a successful career of her own. But when Greg picks up a stray dog named Sylvia (personified by Sarah Jessica Parker) at the park, he develops an attachment that actually begins to threaten his marriage. It soon comes down to a choice: his wife or his dog.

The playwright is interested here in dealing with what is commonly known as a midlife crisis, the dissatisfaction with career and relationships that is said to spring up in men at that point in their lives.

It is a subject that has popped up repeatedly throughout the playwright's work. But the main thrust of the play, the comic conceit, is the interaction between the human characters and Sylvia. As animated by Sarah Jessica Parker, Sylvia has extensive powers of speech, and she and her human masters communicate quite well.

But she is also recognizably a dog, filled with canine concerns, and the humor of the piece derives mainly from watching Parker scampering around, imitating animal feelings and gestures. A little of that goes a long way, despite the actress's considerable imitative skill and the many humorous examples that the playwright has drawn of doglike behavior.

It's hard not to laugh at Parker's hesitant walk, shortly after her character has been unceremoniously spayed. Or the way in which she acquiesces or futilely rebels at the various demands for tricks placed upon her.

A short one-act play with this sort of stuff might have been quite amusing, but at full length (two hours) it feels utterly padded.

Kimbrough, who plays the stuffy newscaster Jim Dial on television's ''Murphy Brown,'' has starred for Gurney before, in the much more estimable ''Later Life.'' He's an actor who is perfect for this playwright, as is Blythe Danner who, as usual, is quite fine, although one wishes that she had more to do here than to act exasperated.

Kimbrough has always been good at letting us see the boyish nature buried underneath the reserved exterior, and he's a delight here, playing with his new-found pal like a child who's been given his first puppy.

Derek Smith rounds out the cast, having a ball playing a variety of roles, including a fellow dog-owner obsessed with canine psychology, a therapist of unspecified gender and a woman friend of Kate's who shares her distaste for large dogs.

John Tillinger has staged the piece with his typical comic precision, and the Manhattan Theatre Club, as usual, has given it an excellent production.

But for all its professionalism, ''Sylvia'' is the kind of evening in the theater that drives people back to television, looking for substance.