No one can accuse Stephen King of dogging it, but the movie version of his gothic thriller about a rabid mutt, "Cujo," reinforces the impression that his powers of invention may be suffering as he sustains a relentless rate of productivity. Last summer's belabored collaboration with George Romero, "Creepshow," and the insurmountable suspension-of-disbelief problems that plague director Lewis Teague while gamely struggling to finesse "Cujo" onto the screen suggest that it may be time for a breather.

"Cujo" no doubt presented fewer difficulties for a novelist than it does for a movie director. The unlucky Teague is obliged to overcome the implausible aspects of the pretext, which require a harmless family pet, a St. Bernard named Cujo, to be transformed into a hellish menace after being bitten on the snout by a bat. A farm dog, the animal is stricken in the opening sequence and appears to languish around strangely oblivious owners and bystanders for several days without anyone but the audience getting wise to such blatant signs of distress as a disintegrating coat, foam dribbling from his jowls and pus oozing from his eyes.

Although the material is conventionally manipulated to provoke terror by exploiting Cujo as a mad dog--a four-footed Jaws as a shameless matter of fact--moviegoers are likely to feel too appalled at the way a sick animal is systematically neglected.

King's most effective and adaptable books, like "Carrie" and "The Shining," usually have an underpinning of family conflict and submerged psychological anger to rationalize the eruption of supernatural horror effects. The effort to construct a similar foundation for the climactic events in "Cujo" is transparently fraudulent. The principal characters, a vaguely estranged couple named Donna and Vic Trenton (Dee Wallace and Daniel Hugh-Kelly) and their 6-year-old son Tad (Danny Pintauro), comprise one family group, but the dog belongs to another family of three, the rural Cambers. There's not the faintest persuasive connection between the tensions in either household and the degeneration of poor Cujo into a rabid marauder.

Since Mr. Camber (Ed Lauter) also repairs cars and the Trentons have an ailing Pinto, the plot is finagled to leave Mrs. Trenton and her little boy under siege a long way from home. Isolated at the conveniently abandoned farmhouse, mother and son must spend the better part of two days inside a locked car sweating, dehydrating, cringing and screaming while Cujo alternately stalks and batters their shelter.

Prior to the showdown, Dee Wallace has been moping around because Mrs. Trenton feels guilty about a clandestine love affair with a local handyman (Christopher Stone). It takes a great deal of generosity to equate her melancholy infidelity with Cujo's sickness or to derive anything remotely redemptive from the spectacle of her eventually becoming such a fierce maternal beast (or infuriated car owner) that she can beat off a rampaging pooch.

An early clue about little Tad's fear of monsters lurking in his closet also proves meaningless, since King never conjures up a serious threat to the child's well-being in the Trenton home or the behavior of his parents. If "Cujo" is supposed to have an allegorical dimension, it's not one that makes a flicker of sense.

Teague, who did a capable, amusing directing job on John Sayles' playful script for "Alligator," must have persuaded himself that "Cujo" was a technical challenge worth accepting. It isn't. CUJO

Directed by Lewis Teague; produced by Daniel H. Blatt and Robert Singer for Taft Entertainment Co.; screenplay by Don Carlos Dunaway and Lauren Currier. Edited by Neil Travis. Music by Charles Bernstein. Based on the novel by Stephen King. Rated R. THE CAST Donna Trenton....Dee Wallace Vic Trenton....Daniel Hugh-Kelly Tad Trenton....Danny Pintauro Joe Camber....Ed Lauter Steve Kemp....Christopher Stone