While First Dog Bo Obama enjoys free rein on the vast, verdant White House grounds, most city-dwelling canines have their outdoor playtime confined to a working-class time share: the public dog park, a mecca for pre- and post-work R&R for their owners. Since the first one opened in Berkeley, Calif., in 1979, more than 600 such fenced-in doggie zones have popped up around the country. There was a 34 percent jump in the creation of such runs over the past seven years. They’re places teeming with conflict and emotion. “As America has moved away from farm culture, we tend to view animals as children,” says Michael Schaffer, author of One Nation Under Dog. “People at a dog run will make fools of themselves.” Professor James Serpell of the University of Pennsylvania’s Center for the Interaction of Animals and Society agrees: “People who normally would never mix are forced into association through their dogs’ needs.” According to Cesar Millan, star of National Geographic’s The Dog Whisperer and HGTV’s Leader of the Pack, “Everyone has their own pack within the big pack of the dog run. People are not as friendly as dogs.” Bloomberg Businessweek recently spent long hours observing dog-owner interactions at various Manhattan dog parks and asked the above experts, as well as body language expert Patti Wood, author of Snap: Making the Most of First Impressions, Body Language, & Charisma, to analyze the findings.