When did the Year of the Dog begin?

It was said on TV in the morning: According to historians, the Spring Festival in 2006 was not the year of the dog, but the year of the rooster. The real Year of the Dog should start after beginning of spring, that is, after the solar terms in beginning of spring. However, this is an old story, there is no need to pursue it, and the law does not blame the public. What is recognized by everyone is correct. People born after the Spring Festival can only be said to belong to dogs, because people nowadays are more accustomed to using attributes to calculate their age.