Like most actors, John Ritter knows there's a downside to working with children or animals: They steal every scene. Now it appears there's another canine thief in Hollywood—"a small, yapping, obnoxious dog," says producer Greg Hoblit, "a wired-up pain in the ass." That's the kind of pooch Hoblit says he wanted for the pilot of ABC's new, critically praised detective drama-dy Hooperman. And that's the kind that Britches, a 32-month-old Jack Russell terrier bitch, turned out to be. In fact, when Britches first met Ritter, says Hoblit, "She did wonderfully, taking a bite out of John's fingers." Adds Cindy James, the terrier's owner: "Not many small dogs can attack with conviction. I taught her like a Doberman."

More like an ambitious starlet. As Bijoux, Detective Hooperman's male mutt, Britches is not only stealing scenes but trotting off with the show. Sniffing out a drug stash, putting the paw on a killer and—a prime-time first for a dog—suffering flatulence, Britches has inspired more yapping among audiences than anyone else on the show.

Ritter, long the star of Three's Company, has apparently decided that two's a crowd. At a recent press conference he made a couple of cracks about Britches. "I hate that dog," Ritter said. When someone suggested the dog would be a star, Ritter added, "Next year the show will probably be called Hooperdog." Now he refuses to comment at all on Britches.

Owner James pooh-poohs the bad-mouthing. Yes, she admits that Britches is independent and stubborn—as befits an ingenue who has appeared in a movie, Harry and the Hendersons, and made a Kibbles 'n' Bits commercial with James's other actor dog, Sebastian. Yet James insists Britches and Ritter basically get along. "Their scenes wouldn't work if John didn't like her," says James. "A dog picks up on your real feelings." Nevertheless Britches isn't exactly wagging her tail over Hooperman. When the show airs each Wednesday night, the dog can be found in her San Fernando Valley home, chowing down her usual snacks of chopped hot dogs or liver and garlic (maybe it's her breath that caused the stink with Ritter). Then she goes over to the TV and dozes off. "Only the sound of her own barking on the show will get her attention," says Marilyn Corcoran, who gives her commands on the Hooperman set. "She'll glance up, then look away and go back to sleep."