Striking that perfect work-life balance can be quite the challenge for those of us with little ones at home, their slobbery faces pressed up against the window, waiting for dad to get home and give them some love—before they take it out on a favorite pair of shoes or all over that new rug. Advertising professionals looking for a pooch-friendly environment need look no further than L.A., where we visited three agencies to find out why having a furball by one’s side makes work life all the better. First up, Mistress. “Having a dog here, I feel, and I think other people feel, very much at home. It’s kind of like playing around, it’s kind of like a living room,” says Jamal Northington, the agency’s IT director, who adds, “You…