Last weekend over a dozen four-legged, sniff-happy guests assailed a bed and breakfast on the Bolinas Mesa. There was not a bomb threat, or any cocaine. The 14 dogs that wandered throughout the Ocean Song Retreat were in search of the scent of birch.

A swab soaked in essential oil made from the pulverized bark of birch trees was hidden somewhere in Creta Pullen’s guest house. According to Candy Bennyi, a professional dog and nose work trainer for the Marin Human Society who was leading the workshop, the oil is one of three kinds used in “scenting,” another name for K-9 Nose Work.

Developed in 2006 by certified detection dog trainers Amy Herot, Jill Marie O’ Brian and Ron Gaunt, the sport uses detection principles to bring everyday dogs a new, scent-based form of competition. Since it began, scenting has spread throughout the country — and West Marin is no exception.

“Could it be in the other rooms?” a dog owner asked. “Could be,” Ms. Bennyi answered. The woman followed as her border collie, Sadie Joy, entered a small room packed with furniture. The dog’s ears stiffened and her eyes set on a tall dresser. “Good girl!” the woman said, rewarding the dog with a piece of cheese. A swab of birch essence was hidden beneath the bottom drawer.

Interior search is one of four exercises included in a K-9 Nose Work trial, along with exterior, vehicle and container searches, usually done with boxes. All of these were completed last Saturday in and around the perimeter of the bed and breakfast. “Wherever we can get permission to have a class, we’ll go,” Ms. Bennyi, who leads classes in banks, malls, pet stores, wineries, feed stores and office parks, said. “It keeps [the dogs] working in different environments,” she added. “It just kinda keeps it fun.”
Ms. Bennyi trains dogs to detect birch, anise and clove oils, usually within five minutes or less.

One Jack Russell terrier, two golden retrievers, three Portuguese water dogs, two labradors and an Irish setter were among the breeds attending the Bolinas class. Ms. Bennyi insists that breed has nothing to do with performance. “I had a chihuahua once and you wouldn’t think a chihuahua would be any good at it,” she said. “At first he was so timid he didn’t even want to go near the boxes. But afterwards he liked it so much that he became the star of the class.”

While dogs receive rewards for finding odors, they also get scolded for breaking scenting etiquette. “No, no, no!” one owner yelled at a Rhodesian ridgeback as he stopped mid-scent to relieve himself on a curious-smelling tree. “Get him out of there,” Ms. Bennyi commanded. “If they urinate in a search area [during] a trial, they are disqualified,” she noted.