I'd heard and read that the doggie poopy problem in Paris is so much worse than in New York or elsewhere in an urban American city. Thus far, I haven't found that to be the case. In fact, I've seen far fewer dogs walking about than I do in New York (or maybe it's that Parisian dogs are smaller than the really large dogs living in New York apartments these days).
Even so, the Luxembourg Gardens suggest that you don't even have to bring your own baggies when you walk the dog there. Along with the baggies that dispense from the bottom of the kiosk, they provide directions by photo, just in case you're not sure of the most hygenic method with which to handle this messy matter.