Some dog lovers can't be dog owners. Maybe their lives are too busy, or their apartment too small. Perhaps a spouse is allergic. But they can be dog owners part time.

The Monster Milers is a group of runners who time-share dogs at PAWS, an animal adoption center in Old City. A runner can check out a dog to join him on a jog through the city.

PAWS already has volunteers to walk the dogs every day. Runners bring adrenaline to the table. Some dogs were built for speed.

"Most dogs are amazing runners," said Carrie Maria, the organizer of the Monster Milers. "You take a dog who is crazy in a shelter, take them out running and in two blocks he's running right by your side."

For the runners, such as Rebecca Baranowski who tries to get out a couple times a week before work, they are forced into an exercise regimen.

"It definitely gets me out on days I otherwise would not have," says Baranowski, who works in Old City. "I feel like I've made a commitment."

The dogs, such as Baranowski's recent running partner Emerson, get more than exercise. The 2-year-old pit bull mix gets a chance to practice being with an owner.

Emerson was skittish for the first two blocks, until she found a plant to pee on. Then she became very excitable when she discovered that every piece of trash along Delaware Avenue had a fascinating smell. Baranowski spent more time coaxing her than running her.

When Baranowski got her out to Penn's Landing, Emerson found her stride and ran along her temporary master.

Consistency is important. Baranowski was trained by the Monster Milers to go on one of a handful of familiar running routes, and to use a short list of commands. That way, the dog will not get confused by 30 different people announcing 30 different instructions.

The dogs learn to be obedient to humans even in a highly aroused state of play, which makes them more adoptable.

"We had one dog that loved to run," said PAWS manager Allison Lamond. "As soon as he would see a runner, he would sit down and wait very nicely for his leash to be put on. Wait very nicely for him to walk out the door. There are certain things they need to do to be rewarded with a run."

That dog was ultimately adopted, by a runner.

Carrie Maria started the Monster Milers last summer, and has 30 runners on the roster. Some come weekly, some come monthly. Some came once and never again. There are 200 more runners on a waiting list to attend the two-hour orientation sessions.

This spring, Maria plans to launch another branch of the Milers at the PAWS center in Grey's Ferry.