When they set out to interview Chicago firefighters for their book, The Firefighter’s Best Friend: Lives and Legends of Chicago Firehouse Dogs, brothers Trevor and Drew Orsinger realized that they would probably be viewed as interlopers.

After Sept. 11, as the NYFD logo was being sewn onto ball caps and T-shirts around the country, Chicago firefighters were as wary as their New York colleagues of seeing their image exploited for commercial gain. Since they were relying heavily on oral history, the Orsinger brothers, who had no journalistic experience, had to muster enough interviewing tact to open up a guarded group.

“They kept their cards close to their vest,” says Trevor Orsinger, a Chicago-based public defender. But eventually even the crustiest old-timers started talking—sometimes not until after 10 minutes of awkwardness—and they showed a sensitivity that sometimes shocked the Orsingers. “One firefighter was almost crying,” says Drew Orsinger, a Coast Guard officer who lives in D.C.’s McLean Gardens. “He was choking up. He had some amazing stories.”

The idea for the fire-dogs project first struck the brothers while they were visiting a Chicago firefighter friend on Dec. 31, 2000. When an arthritic old Rottweiler made her way out of the back of the house, the firefighters started swapping anecdotes, including one about the time she’d cornered a pair of teens who had broken into the firehouse while the crew was on a run. One hoodlum climbed the stove, the other a vending machine. When the firefighters returned, they taught the kids a lesson—by playing a game of cards rather than calling off the dog.

The Orsingers tracked down more than 30 dogs currently living in Chicago’s roughly 100 firehouses, a crop that makes Chicago the only American city that still has a major contingent of fire dogs, according to the authors. (Animals are not allowed to live in D.C. firehouses, according to D.C. Fire and Emergency Medical Services Department spokesperson Alan Etter.)

The book documents more than 300 pups since the Great Chicago Fire of 1871, including those dogs of the early 20th century who have achieved mythical status. (Felix, of Engine 25, could climb ladders and ferret out trapped victims.) “It was like we got our Ph.D.s in fire dogs,” says Drew.

Fire-dog studies turned out to be an interesting field, full of legends that needed debunking. Although an athletic Dalmatian usually comes to mind, the most common firehouse dog in Chicago is a stray mutt. (Dalmatians led horses well—which is why they served as the original fire dogs in the 18th century.) Most function as guard dogs for the houses while firefighters are answering calls, though some, such as the dog that trots into the street to stop traffic when the rig returns to the firehouse, develop special skills.

Many dogs, Drew says, won’t let you in the firehouse unless your clothes give off the distinct smell of house fire. So the brothers had to win over the trust of the dogs as well as the firefighters. The latter, Trevor adds, seem glad they opened up. “One guy had a picture of him with his dog in the book,” he says. “He was misty-eyed. Not by the book, but by the fact that their relationship was preserved.” —Dave Jamieson