SHELBURNE FALLS, Mass. -- When Gary Mikus learned that an incurable nerve disease was paralyzing the hind legs of his German shepherd, he immediately dismissed the idea of putting the dog to sleep.

Then he spotted an ad in a pet food store: "Eddie's Wheels For Pets. Help for Handicapped Pets." Now the dog named Bear, Mikus' constant companion for a decade, has a lot of living left to do -- much of it in his new wheelchair.

"He's healthy in every other way," Mikus said. "Until something tells me otherwise that he's failing, I'll do everything I can to keep him mobile and happy."

A growing number of pet owners are turning to custom-built wheelchairs to restore mobility to furry friends whose legs, hips or backs don't work. The owners' goals are simple: to reward their pets' unconditional love with whatever it takes for the animals to live normally.

The two-wheel carts support the dog's midsection with a padded saddle, and are secured with a shoulder yoke and chest strap. Most dogs have rear-wheel carts to compensate for lame hind legs, although some front-wheel carts are being ordered for animals with front-leg problems.

Donna Blain's 7-year-old Maltese named Gizmo hopped and hobbled on his deformed front legs before she adopted him a year ago. She ordered his cart after learning the odd gait had damaged his spine and would have required surgery.

Now he wheels himself around for hours on sidewalks, in parks and anywhere he can find treats and praise.

"He's into everything," said Blain, of Woodstock, Conn. "He just wants to live, after all those years of really hobbling and not being able to get where he wanted to be."

Eddie and Leslie Grinnell, founders of Eddie's Wheels, built their first pet wheelchair in 1989 when their 10-year-old Doberman, Buddha, lost the use of her rear legs because of disc disease and spinal problems.

Their veterinarian, impressed by Buddha's revived mobility and vitality, started referring others to the Grinnells. In 1998, they started their own business.

Similar wheelchair makers can be found in many states. (One Texas source is dogstogo.net, based in Rosharon, 25 miles from Houston.) Most dog carts start around $250 and can exceed $500 based on the size of the dog, while the cost of wheelchairs for other animals can vary depending on the type and size of animal.

Since launching the business, Eddie's Wheels (www.eddieswheels.com) has shipped carts worldwide -- the largest to a 220-pound Saint Bernard in Great Britain -- and has made wheelchairs for several cats, a ferret, alpacas, goats, sheep, a rabbit and a possum.

They even keep a supply of tiny wheels on hand for a gerbil or hamster.

Veterinarian Derek Fox, a University of Missouri professor specializing in orthopedic surgery for dogs, cats and other small animals, said pets that once would have been irreversibly crippled are benefiting from a variety of advancements: improved hip and joint replacements, better physical therapy and wheelchairs.

"Even if a treatment is expensive, these are people who say they'll do anything to keep their pet moving, to keep them happy, to keep their quality of life up," he said.

Many of the dogs who need the chairs become disabled from degenerative myelopathy, a neurological disease common in German shepherds, golden retrievers, Labradors and other large sporting breeds. Others, like corgis and dachshunds, are vulnerable to disc and spine problems that eventually leave them lame.

"Dogs don't understand why this is going on, but they're very accepting: 'Oh, this is the way I am today.' So when we put them in the cart, they're like, 'Oh, now I'm back to normal.' I can go where I want," Leslie Grinnell said.

That was the case with Max, an 8-year-old German shepherd. His owners, Gordon and Linda Landry of Granby, said his degenerative myelopathy left him dejected and hobbling behind their other dog, Molly.

As he tried his new cart for the first time, the dog whimpered at the door to go outside and promptly wheeled his way down the walkway, around the parking lot and past Molly as she peered at him from the Landrys' truck.

"This just amazes me," Linda Landry said as she watched him, laughing at his vigor. "We never get to see him like this anymore. It's like having a younger Max back."