The Broadway comedy “Sylvia” opened Oct. 27 — but really, that’s just an excuse for everybody to talk about their dogs.

The play chronicles a middle-aged man’s relationship with a dog, and its stars Matthew Broderick, Julie White and Annaleigh Ashford (playing the dog) are all dog owners. So is director Daniel Sullivan. How hard was it for Sullivan to keep rehearsals from deteriorating into people telling stories about their pets?

“I didn’t stop it,” Sullivan admitted. “We just let it happen.”

Anyone who read the program bio for White probably would have guessed she’s a dog person. “It’s basically an obituary for my dog,” she said at the opening night party at Bryant Park Grill. White’s dog is 14 and facing the perils of aging with bravery. “When I go, I want to try to do it like Lulu!”

Broderick, meanwhile, comes to “Sylvia” 20 years after his wife, Sarah Jessica Parker, portrayed the dog in the play’s Off Broadway premiere. Every now and then he spots his current dog, Kissy, in Ashford’s performance. “Annaleigh does a good paw on the arm,” he said. “My dog does that.”

But Ashford is taking her cues from her own pup. “Tonight I did like a weird banana butt thing when I was trying to get a smile out of Matthew,” she said. “That’s totally my dog.”

She spends a lot of time munching Scooby snacks during the show — gluten-free, thank you very much, because she’s got celiac disease. “My kibble are these cheese twists that I love,” she said. “I picked them. They don’t taste gluten-free at all!”