In the urban area, we are more than 12 million. Everyday more people move to Paris with a population density of more than 21,000 persons per km² (54,900 /sq mi) whereas in Tokyo there are only 6,030 persons per km².
In France we beat the European record with 42 million animals for 62 million inhabitants. 52% of French people have at least one animal at home. There are 8.1 million dogs -- 1 for 8 inhabitants (against 1 dog for 5 inhabitant in US and 1 for 16 inhabitants in Germany).
So you can understood that French people really like dogs! You can see all kinds of dogs hanging around in Paris. Fat, skinny, tall... ugly ! It's really nice to take pictures of them, owners are always glad to ask the dog to take the pose, and it's a cool way to meet people in the street.
However it's not always easy to have them in our little flat; sometimes people have really huge dogs. I don't think the Parisian life is a dream for dogs... Also people are not used to removing dog droppings in the street, and even if Parisians are learning bit by bit, it's still makes the city dirty!