SAN FRANCISCO – From the state that popularized purse puppies, drive-through dog washes and gourmet dog food delivery comes the latest in canine convenience – a company that contracts out dogs by the day to urbanites without the time or space to care for a pet full time.

Marlena Cervantes, founder of FlexPetz, bristles when people refer to her five-month-old business as a rent-a-pet service. She prefers the term “shared pet ownership,” explaining that the concept is more akin to a vacation timeshare or a gym membership than a trip to the video store.

“Our members are responsible in that they realize full-time ownership is not an option for them and would be unfair to the dog,” said Cervantes, 32, a behavioral therapist who got the idea while working with pets and autistic children.

“It prevents dogs from being adopted and then returned to the shelter by people who realize it wasn’t a good fit,” she said.

FlexPetz is currently available in Los Angeles and San Diego, where Cervantes lives. She plans to open new locations in San Francisco next month, New York in September and London by the end of the year.

For an annual fee of $99.95, a monthly payment of $49.95 or a per-visit charge of $39.95 a day, (discounted to $24.95 Sunday through Thursday), animal lovers who enroll in FlexPetz get to spend time with a four-legged companion from Cervantes’ 10-dog crew of Afghan hounds, Labrador retrievers and Boston terriers.

The membership costs cover the expense of training and boarding the dogs, home or office delivery, collar-size global positioning devices, veterinary bills and liability insurance. They also pay for the “care kits” -leashes, bowls, beds and pre-measured food – that accompany each dog on its visits.

Charter FlexPetz member Shari Gonzalez said she was thinking about getting a dog when a dog trainer she consulted suggested part-time ownership. At first, she had reservations.

Gonzalez, 22, never doubted there was room for a dog in her heart. The issue was her life, which included a small two-bedroom apartment and a full-time schedule of college classes in San Diego.

“I was thinking, ‘How is a dog going to bounce from house to house and be OK with that?’ ” she said. “I didn’t want a dog that would come into my place and pee.”

Since signing up, Gonzalez said she has tried out several dogs but fell in love with a black Lab named Jackpot. They spend an average of one day each weekend together. He sleeps at her apartment and she takes him on hikes, to the beach and to parks frequented by other dog owners.

“I never even thought that was a possibility,” Gonzalez said. “I thought you either owned a dog or you didn’t.”

Gonzalez recently met another of Jackpot’s part-time companions, graphic designer Jenny Goddard, 33. Goddard, who is married with a 6-year-old son, said having a dog a weekend or two a month has been perfect for her busy family and encourages them to spend more time together outdoors.

“It’s funny,” she said. “He is so friendly and immediately playful with us, people are surprised he is a rental dog.”

The idea of commitment-free pets is not entirely new. Most private animal shelters, for instance, encourage volunteers to become temporary foster families to animals awaiting adoption.

Melissa Bain, a veterinarian with the Companion Animal Behavior Program at the University of California at Davis, said she had concerns but no hard-and-fast objections to a service like FlexPetz.

“It depends on the people and it depends on the animal,” Bain said. “Some dogs may be fine and some may become stressed because they are moving from home to home.”