Five dogs wagged their tails, and some barked with excitement. Each was eager to get to the “work” of using their noses to sniff every inch of a fenced indoor course randomly strewn with dog toys and other items.

One at a time, each dog entered the course on a 10-foot leash held by their owner. Each was praised for sniffing boxes, suitcases, purses and tote bags hanging from the fence. Hidden within three of those objects were small metal cans containing a Q-tip scented with birch, anise or clove.

The little cans are the “finds,” and when a dog finds it, lavish verbal praise is followed by a food treat.

The dogs are enrolled in a class called scent work. But it’s not really work because the dogs are doing what they love to do by their very nature — sniffing and processing the world through their noses, as dogs have always done.

This recent one-hour class was at Keystone Canine Training Club in Baldwin Borough, one of several local training venues where nose work is offered. Word-of-mouth is fueling the growing popularity of nose work because dogs love the classes, and owners are happy to see their dogs enjoying the activity.

Many dogs attend nose work classes just for fun. For the more competitive owner, there are ribbons to be won and titles to be earned from the National Association of Canine Scent Work, which held the first trial in 2009.

In the recent Keystone class, some of the canine students were mixed breeds from shelters and rescues: border collie mix Toby, 2, with Cherri Estep of Mt. Lebanon; miniature schnauzer mix Howie, 8, with Pat Warnick of Munhall; and Molly, 8, a Shih Tzu-Lhasa apso mix, who also is a therapy dog, with Amy Sandhapen of Whitehall.

The lineage of those dogs bring up a good point: Scent work isn’t just for the sporting breeds (pointers and retrievers) and hounds (including bloodhounds) that have been bred for centuries to track and hunt.

“We’ve never had a dog (of any breed) that did not enjoy doing nose work,” said Maribeth Hook, of Point Breeze, who is teaching the class with Amy Wustin, of Bethel Park.

“We start beginner dogs searching for hot dogs,” Wustin said.

Dogs quickly advance beyond food searches. Howie, at only his second class, was enthusiastically finding the tins of birch, anise and clove, which are not scents that dogs would usually encounter in their homes or on walks in their neighborhood. Those are the scents used in NACSW trial competitions.

Pam Lewis of Bethel Park enrolled Crystal, 13, in nose work after the Samoyed had to retire from agility, which involves fast-paced running and jumping.

“Crystal is a very social animal, and she still loves to go places and do things,” including therapy dog visits at nursing homes, Lewis said. Crystal has even participated in the “dog weddings” that Keystone Club members stage at nursing homes.

Nose work can be done by dogs of all ages and fitness levels, the instructors noted.

Because dogs start out working on leashes, not a lot of prior training is needed, although Hook recommends a basic obedience course so that dogs are attentive to the wishes and commands of owners.

Dogs do need to be accustomed to spending a short time in a crate because that’s where they are put while awaiting their turn at the scent work course.

Because dogs do nose work one at a time, dogs that are what trainers term “reactive” can come to classes. Reactive dogs are either aggressive with other dogs or fearful around them. However, the Keystone instructors said nose work usually improves the behavior of reactive dogs because it increases their self-confidence.

All dogs doing nose work form a tighter bond with their owners, Hook and Wustin said.

Nose work also is especially good for high-energy dogs such as Dalmatian Rainn, 4, who comes to classes from Washington, Pa., with Jack and Carol Seubert. Dalmatians need a lot of exercise, and Rainn takes her owners on frequent 4-mile walks. Rainn is always happy and pleasantly tired after her nose work class, Mrs. Seubert said.

Once they have some experience under their collars, nose work students can work off leash and outside in Keystone’s fenced exercise area. Nose work is more challenging there because the venue includes the scent that all dogs know and love — canine urine.

Two experienced dogs did some outdoor nose work. Wustin’s German shorthaired pointer Temperence, 3, and Hook’s Australian shepherds, Frisco, 2, and Kobi, 8. Tempe even searched a car, locating a “find” hidden by Hook.

“Wind takes the scent and disperses it,” Wustin said, making outdoor nose work a bigger challenge. “It’s easier when it’s cold because the scent stops. In hot and humid weather the scent disperses.”

Tempe has earned NW1 and NW2 titles from the National Association of Canine Scent Work.

Go to www.keystonecanine.com for more information about scent work and a broad array of obedience and agility classes. The training facility is at 5167 Brownsville Road. Seven scent work classes are $100 for nonmembers and $30 for members.

Hook teaches nose work and obedience at the North Side shelter of the Animal Rescue League/Western PA Humane Society (www.animalrescue.org), but future nose work classes have not yet been scheduled.

Animal Friends (www.thinkingoutsidethecage.org) has The Nose Knows classes, but they are sold out at the Ohio Township shelter through late May.

Misty Pines Pet Company and Dog Park (www.mistypinesdogpark.com) in Franklin Park regularly offers scent work classes, but none are listed on the website.

Visit www.nacsw.net for more information. The site includes “tips for practicing K9 nose work at home,” which includes hiding food treats or toys around the house. That organization’s Facebook page is its registered trademark name, “K9 Nose Work.”