If the Sonoma-Marin Fair has gone to the dogs, it's in pretty good hands ... er, paws.

Joy the St. Bernard, Jack the cane corso and Merlot the Portuguese water dog were a hit Wednesday as they and their handlers wandered around the Petaluma fairgrounds during the five-day fair's opening day.

Those three working-breed dogs, and others, were part of the "Meet the Breeds" exhibit, where dog breeders and enthusiasts introduce canines of all varieties to fairgoers with hopes of educating and bringing smiles.

"The fair's going to be dog-centric this year," said fair Board President James Burleson as the gates opened and lines of attendees streamed in at midday.

This year's theme is "Dog Days of Summer" and Friday is the 25th anniversary of the World's Ugliest Dog Contest, always one of the best-attended events of the fair.

"She loves getting petted and meeting people," said Vanessa Engelbach, Joy's handler.

At 130 pounds, Joy, 4? years old, can be intimidating. But in addition to being a champion load-puller able to lug 3,000 pounds, she's also a therapy dog, so she reads people well.

"If someone is scared, she lays down," Engelbach said, as four preteens stopped and tentatively approached the tri-color beast.

Inside Beverly Wilson Hall, other dogs were preparing to greet folks near the fair carnival midway and food booths.

Jack, a 5-year-old Italian mastiff, or cane corso, wowed visitors with his impressive size (128 pounds and a head the size of a dinner plate) and sweet disposition.

"People have three reactions: They're scared, they want to see if he's mean or they're in awe," said handler, Alexia Fino, handing Jack a treat. "They're great dogs."

"They're all-purpose farm dogs," explained handler Gabriel Rodriguez of Jack, a retired show dog.

Merlot is an 8-year-old retired breeder whose daughter Ladybug is the top winning Portuguese Water Dog in history, said Aviator Kennel owner Mike Dugan of Shingle Springs, near Sacramento.

"She's the same breed as President Obama's dog," he told visitors asking about her.

In addition to canine exhibits and displays, other, more traditional attractions brought people out.

"We made a beeline to the funnel cake, then the donuts," said Forestville's Ame Nultemeier, with her son, Darrell, 2, daughters Mackenzie, 9, and Arianna, 18, and her friend Heidi, 18.

Their plan was to "eat as much fair food as possible," Nultemeier said. "And ride some rides," Mackenzie added. "I'm looking forward to going into all the houses, especially the mirror house."

(You can reach Staff Writer Lori A. Carter at 762-7297 or lori.carter@pressdemocrat.com.)