What country has the most dogs?
Kevisaurus is correct. The US has the most dogs. Estimates vary from 46 million to 61 million according to various sources on the Internet. That also gives the US the highest dog ownership rate in the world. According to the American Vetinerary Medical Association, 37.2 per cent of US households owned a dog in 2007.
However, Kevisaurus not quite on the mark re China. Brazil has the second highest number of dogs (around 30 million). China only has around 20 million dogs (maybe that's because more are eaten than are kept as pets).
A country with a dog ownership rate almost as high as the US is South Africa (maybe that's because they need them there as guard dogs more than as pets)