A dog trots on the Minipacer, a treadmill for small dog, in Las Vegas, Nevada. REUTERS/Daria Artsybasheva/DogPACER/Handout

As the obesity rate soars among Americans, their dogs are getting potbellied, too, encouraging fitness companies to come up with a range of equipment and classes to get pampered pets back into shape.

From canine-tailored treadmills, to puppy pedometers and group fitness classes, there's no shortage of tools to trim and tone the sagging paunches of pooches.

As part of his fitness routine, Rocky, a rotund dachshund, traipses a mini-treadmill designed for small dogs.

"When Rocky first came to us, he looked like a small marine animal," said Dr. Dennis Arn, veterinarian at the Desert Inn Animal Hospital in Las Vegas, Nevada. "He's got a waistline now and his conditioning is significantly better."

Just like their owners, obesity affects pets' longevity and quality of life. About 53 percent of adult dogs are classified by their veterinarians as obese, according to the Association for Pet Obesity Prevention.

To combat the weighty issue, Tufts University's Cummings School of Veterinary Medicine in North Grafton, Massachusetts, announced the creation of the nation's first obesity clinic last month, geared specially towards pets.

"If you can't lay your hands on them and feel the ribs pretty easily, they're obese," said Arn, adding that too many pet owners reward their charges with treats.

"As a blanket statement, a dog needs at least 30 minutes (of exercise) a day," said Geralynn Cada, who has been training dogs for more than 30 years. "A dog who is less active is less happy and has more health problems."

Cada, who is based in Nevada, teaches classes such as dog yoga, puppy Pilates, and a canine interval training course known as Retrieve and Burn.

Physical issues aside, dogs that are denied exercise often develop behavioral problems, she said.

"A tired dog is a happy dog," Cada said. "If your dog gets bored, they'll search for purpose and that purpose will be to chew up your wallet."

To burn off her high-strung husky's extra enthusiasm as well as calories, Cada runs him regularly on his dog treadmill, dubbed the DogPACER.

David Ezra, CEO of DogPACER, said he got the idea for the canine cardio machine after observing clients at his fitness centers.

"I thought, "Why not a treadmill for dogs?"" he said.

Hundreds of canine treadmills - which sell for $500 and come in regular and mini sizes - have been sold since they hit the market seven months ago.

"We've run over 1,000 dogs at this point," said Ezra, adding that 60 to 70 percent of the treadmills go to dog owners, including seniors whose health problems prevent them from exercising their animals.

Others are purchased by grooming salons, veterinarians, police and government agencies, and animal rehabilitation centers.

"Grooming facilities will throw the dog on (a treadmill) to de-stress them before grooming," he said, adding that dogs must be supervised and will initially be taken aback by the equipment.

Studies have shown that people who wear pedometers routinely walk more. Perhaps in that spirit, developers of Tagg, a pet location device, developed an activity monitor that makes it possible for owners to keep tabs on their dog's exercise.

"Tagg's combination of activity monitoring and GPS location tracking puts pet parents in control of their pet's well-being," Dave Vigil, president of Snaptracs Inc. which created Tagg, said in a statement.

Cada is so devoted to keeping animals fit, she has also devised ways to stimulate her dogs mentally.

"I have them doing a mental obstacle course for me," she said. "I'll have them sit down, roll over, jump on and off the bed, and do all the tricks they know in a random order."

The animals will also fetch and engage in a series of rapid-fire hand-to-paw high-fives.

"It's like a test," she explained, "for a treat."