SAFETY FIRST: Most trips provide equipment, meals and instruction.

By SARAH ROBERTSON

 WHEN Barbara Corbato booked a trip to Ontario's wilderness region with an adventure travel company, she and her companion, Bella, spent a long weekend canoeing, hiking, swimming and lounging by the campfire. But Bella isn't her best friend or her daughter. She's her black Labrador retriever.

"Bella is a complete water fanatic," said Ms. Corbato, a violist in Grand Rapids, Mich. "She swam pretty constantly. Going on a trip that was tailored to your animal was a lot of fun."

In just the latest twist on the billions spent on adventure travel, a growing number of pet-friendly travel outfitters are offering everything from winter hiking jaunts in the Catskill Mountains of New York to tubing trips down the Yampa River in Colorado. Dog Paddling Adventures, a Canadian company offering cross-country skiing, hiking and canoeing expeditions for pets and their owners, says its business has quadrupled since it opened in 2000. One outfitter even plans to offer a $4,000 dog hike from Aspen to Crested Butte, Colo., with a stay in a luxury inn and the return trip in a chartered plane.

"There are a lot of people who would travel with their dogs like they would their kids or friends," said Susan Sims, editor of Fido Friendly, a travel magazine for pet owners. "They don't think anything of it."

Why should they, given Americans' ever-growing obsession with their pets, which has people shelling out an annual $32.4 billion on their companion animals last year, for everything from designer cat beds to special doggy massages? And while spending on pet adventure travel is still a small segment of the adventure market, a growing number of small outfitters are getting into the business. Many of them, like Donna Carsten, the founder of Bailey Knows Travel, in Sherman Oaks, Calif., started offering pet trips because they were frustrated by not being able to take their dogs along. "I don't want a vacation from my dog," Ms. Carsten said. "I wanted to offer trips where the animals are part of the experience."

And for every dog lover organizing skijoring trips in Ontario (a kind of dog-sledding without the sled — the dogs pull their owners on cross-country skis) or hiking expeditions to Moab, Utah, there seems to be another entrepreneur ready to sell pet-ready hiking or adventure gear. Ruff Wear, a Bend, Ore., dog-gear company, says sales of its items, like canine backpacks and doggy hiking "boots" — socklike slip-ons that help protect paws on the trail — have grown 30 percent over the last two years. Among the popular treats at Zuke's, a Durango, Colo., pet food company, are PowerBones for dog hikers. Packed with carbohydrates and "quality fats" for endurance, they are the dog equivalent of Balance Bars. Then there are the dog sleeping bags and $75 backcountry "pup tents" from UhlrGear of Dublin, Ohio. "The customers are ecstatic," said Marc Ladyga, an owner of UhlrGear. "They love them."

Or at least their owners do. Lori Miller-Levine took her 3-year-old golden retriever, Beauregard, on a camping and float trip last July organized by Colorado Canines. Beauregard attended with his own life vest, booties, portable water dish and fleece-lined Therm-a-Rest mattress for extra-cushy sleeping in the tent. "You name it, he's got it," said Ms. Miller-Levine, a 43-year-old jewelry designer from Boulder, Colo.

OF course, people have been taking their pets along on vacation for years. But in many cases, that meant staying in the limited number of economy hotels willing to let animals bunk with their owners. And pets were rarely invited along on active vacations. Traditional outdoor-adventure travel outfits rarely allow pets to join in and some wilderness areas forbid dogs because of endangered species or historical structures in the area. In other places, dogs are only allowed if they are kept on a short leash.

But with people increasingly thinking of pets as their family members, a growing segment of the travel industry has become willing to open its doors to four-legged companions. In its 2004 "Traveling With Your Pet" guide, AAA lists more than 12,000 lodgings that accept pets, up 8 percent from last year — double the increase from the year before

And at a time when animal obesity rates are approaching human ones — American veterinarians say over half the pets they see are overweight, according to a study conducted last fall by the Purina Pet Institute — experts say a weekend in the woods may be just the thing for some out-of-shape pooches. Still, Dr. Peggy Rucker, a veterinarian and spokeswoman for the American Animal Hospital Association, suggests owners take their pets for a check-up before their first trip and put them on a training regime to get in shape. Owners should also think carefully about their dogs' physiology and personality before signing up. "You can't envision someone taking their Chihuahua and playing out in the snow for very long," Dr. Rucker said. "You'll have a Chihuahua Popsicle."

It's hard to know, of course, whether dogs really want to take up backpacking or backcountry canoeing. After all, "not all are hunters and are looking for miles of open space," said Bob Vetere, managing director of the American Pet Products Manufacturers Association. For many breeds, he added, "if you keep them on the front yard and roll a tennis ball to them, they'll be just as happy."

Indeed, in some cases, the canine participants' ideas of a good adventure hasn't quite matched up with the weekend plan. When Cindy Garbacz took Bailey, her Labrador, on a Dog Paddling Adventure canoe trip, she envisioned a companionable ride with her dog through Canadian lakes. But the dog jumped overboard twice. "Bailey wasn't too thrilled about the boat experience," said Ms. Garbacz, a computer consultant in Buffalo. "She thought she could get there faster in the water." (A bigger problem: Ms. Garbacz, a first-time canoeist, found the experience "a lot of work.")

Adventure trips among humans don't always go that smoothly, of course. But people can usually just ignore each other at cocktail hour if they don't get along. With animals, managing personality issues can be tougher. Most pet travel companies reserve the right to dismiss unruly participants, and will send animals home for being overly aggressive. Others conduct an intense screening process, sending out detailed questionnaires about the pets before they admit them. Camp Dogwood, a Chicago outfit that runs weekend trips to the Illinois countryside, requires that dogs with "space issues" wear orange bandanas.

But in many cases, the real issues aren't between animals, but between owners — especially when a spouse or partner isn't keen on the idea of adventuring with Rover.

Jeannie Hosey, of Grand Rapids, Mich., thought a weekend spent canoeing with her 4 1/2-year-old Labrador, Scout, sounded like a great idea. But her husband, Tony Travis, viewed camping with the dog as too much trouble. Her solution: She and the dog went away to the Canadian wilderness for the weekend, leaving Mr. Travis at home. "I think the whole idea is funny," Ms. Hosey said. "He does, too.