MILL VALLEY, Calif. -- There was plenty of yip-yapping, tail-wagging fun going on in one particular park this month, and Sadie, Shelby and Dilly Two-Step didn't much care that they romped on three fast legs instead of four.

All manner of purebred and mutt - sleek, fuzzy, tall and small - converged on Mill Valley Dog Park for the monthly meeting of the Northern California contingent of Tripawds, an online community for canine amputees and their owners.

Cindy Sipple, of Dublin, Calif., whose chocolate Labrador Ruby had her right front leg amputated in December, said, "They don't think, 'Boy, I wish I had that other leg that I used to have.' They're so much in the moment."

Ralph Kanz, of Oakland, Calif., who cares for three, three-legged German shepherds, said Northern California members of Tripawds, including many from the East Bay, began getting together in Mill Valley about three years ago.

One couple traveled all the way from Southern California for Saturday's event. Carla Ocfemia of San Francisco prepared a cake for the dogs made from peanut butter, bananas and bacon. A few of the dogs - referred to as tripods by many owners - lost a limb due to a traumatic accident; but many more had a leg removed because of a cancerous tumor.

Jim Nelson and Rene Agredano created Tripawds.com after their German shepherd, Jerry, was diagnosed with osteosarcoma in 2006 and had to have his left front leg amputated.

Agredano said she and her husband, Jim, created a blog to chronicle their experience dealing with Jerry's cancer. Agredano said that when readers of the blog began asking them medical questions they couldn't answer, they added a discussion forum to the website in 2007.

"All of a sudden people from all over the world started finding our site," she said.

Nelson and Agredano sold their business and house in Eureka, Calif., and traveled the country in a recreational vehicle with Jerry until he died in 2008. Their story was included in a documentary titled "Why We Love Cats and Dogs," which was aired on PBS's "Nature" program.

John Hollenbeck, a sergeant with the Orange County, Calif., Sheriff's Department, said, when his dog Max had his leg amputated because of cancer, "It felt like we were the only people in the world who had this problem. Then my wife happened to find the forum online, and it was a lifesaver for us."

Max died 15 months after losing his leg. Hollenbeck no longer owns a tripod; but he continues to stay in touch with the people he has met through Tripawds.

"These people are our friends," Hollenbeck said. "We talk to them online. We know these people a lot better than we know a lot of people we live near - because you go through such an experience trying to get your dog through cancer."

Karen Riley, of Livermore, Calif., whose three-legged pug, Maggie, died of cancer two years ago, said one of the things that Tripawds does best is help people decide whether to amputate or euthanize.

Agredano said, "For a lot of people, it's a shock to see a tripod. What we do is we try to change their reaction from pity to amazement and get them to see these dogs don't care."

Agredano said, "When you see these dogs getting along on three legs and not caring about anything except having a good time, it's a great reminder that we should all live our lives like that."

Riley said, "On the website, we say: Be more dog. Appreciate every day that you have."