A couple of years ago, Brad Perry's dogs started having joint problems. Cowboy, the golden retriever, developed a severe case of arthritis, while Mr. Jones, the mutt, tore the ligaments in both of his knees during some overenthusiastic play.

"It was so sad. They wouldn't even come to the door to greet me they were in so much pain. It just broke my heart," recalled Perry, a tractor-trailer driver from Alexandria, Ky.

Perry gave the dogs all sorts of medications, but nothing worked, and he knew such medications could result in kidney and liver damage. The dogs' suffering became so great, Perry considered putting the pets down. But late last year he heard about a veterinarian in his area who performed stem cell therapy on dogs to regenerate and repair their joints and figured it was worth a try.

Cowboy underwent the procedure first. Mr. Jones followed a few months later. Perry said that within 10 days of receiving treatment the dogs were like puppies again, chasing his kids, running around in the park and swimming in the lake.

The treatment Perry's dogs received was developed by MediVet America of Lexington, Ky., one of several companies that sell equipment and training to veterinary clinics around the world. MediVet has more than a thousand clinics. Participating vets have performed more than 10,000 stem cell procedures about 7,000 of them in the past 12 months.

An operation like the one Cowboy and Mr. Jones underwent takes several hours. To start, the vet harvests a few tablespoons of fat cells from the pet's abdomen or shoulder, then spins the cells in a centrifuge to separate out the stem cells that are naturally present in fat. Next, the cells are mixed with special enzymes to "digest" any residual fat and connective tissue, and are then "activated" by mixing them with "plasma rich platelets" extracted from the animal's blood cells. The mixture is stimulated under a LED light for 20 minutes or so to further concentrate the stem cells. Finally, the newly awakened cells are injected back into the damaged joint.

Jeremy Delk, MediVet's chief executive officer, said that the therapy works because stem cells are the only cells in the body that have the ability to transform themselves into other types of specialized cells -- such as cartilage -- making them a potent tool for repairing damaged and deteriorating joints. There are 50 to 1,000 times more stem cells in the fat than bone marrow, a source that was more consistently used in animal and human -- stem cell therapy until the fat method started becoming more popular.

"As we age, humans and animals alike, our stem cells are starting to die off so we have fewer. What we are able to do with these techniques is isolate the cells in very large numbers, wake them up and put them back into the area that needs help," he explained.

While still largely unavailable to their owners, stem cell therapy from fat cells has been offered to our furry friends for several years. With fewer regulatory hoops to jump through in veterinary medicine and no contentious religious debates, experimental procedures are often tested and perfected on animals decades before they're green-lighted for use on humans.

One of the things veterinarians and owners alike praise about the procedure is it can be completed in one day, and all at the vet's office. Stem cells can also be banked for future injection so the animal does not have to endure extraction again.

John Sector, the owner of Shelby St. Veterinarian Hospital in Florence, who performed the surgery on Cowboy and Mr. Jones, had high praise for the therapy.

"This is potentially a game changer. We're seeing incredible results in the joints. We also see some unexpected improvements in other things, like skin conditions," he said.

Stem cell therapy is not just for pets who curl up on couches or ride in the backseat either. Delk said horses, donkeys, zebras and lions are also regular stem cell patients. He and his team recently traveled to the Middle East to perform the therapy on some prized racing camels.

However, stem cell remedies, even for animals, are still considered experimental. Shila Nordone, the chief scientific officer at the AKC Canine Health Foundation, a nonprofit group that funds health research for dogs, said that its use for joint regenerative purposes is exciting, but that the lower regulatory bar in animal medicine is both good and bad.

"It's good because we can do things sooner for our patients without 10 years of expensive clinical trials, but bad because we are still in the process of establishing best practices to ensure the procedures are the safest and most effective possible," she said.

Studies funded by the Health Foundation and others have been promising. One study of more than 150 dogs found improvements in joint stiffness, mobility and other joint health indicators in nearly 95 percent of arthritic cases. In some patients, improvements were seen in as little as a week while others took up to 90 days and required multiple injections.

The cost of a single procedure is $1800-$3,000, depending on the area of the country, the species of animal and severity of joint damage. Even those with pet insurance can expect to pay out of pocket.

Owners like Perry believe it is worth every penny.

"They are completely different dogs. It absolutely changed their lives," he said of Cowboy and Mr. Jones. "It changed mine too -- I got my dogs back."

More:

Arthritic Dogs Healed With New Stem Cell Therapy - ABC News