The story goes that all the animals wanted to be a zodiac sign when the Jade Emperor decreed to select the twelve Chinese zodiac signs. According to the standard, however, only the animals helpful to human beings could be selected.
Therefore, all the animals came to the Jade Emperor to show their merits and prove that they were good assistants to human beings. Nevertheless, the origin of zodiac dog was related to the cat.
Legend goes that both the cat and the dog had a close relationship with humans. The cat thought the dog ate too much and slept in front of the door all day without any contribution while the dog thought the cat only ate the good food and did nothing but scaring the rat all day. They argued and asked the Jade Emperor to decide which side was right.
The Jade Emperor asked the dog: "how much do you eat for a meal?" The dog honestly replied: "I watch the door and guard the house every day, and I eat a bowl of food for a meal." Then, the Jade Emperor asked the cat: "what about you?" On a sudden inspiration, the cat said: "I can chant scriptures and catch rat and I eat every meal an oil lamp of food for a meal." The cat just wanted to tell the Jade Emperor tactfully that it not only ate an oil lamp of food, but also earned its own living by catching rat, so its contribution was bigger than the dog.
After listening to what the dog and the cat said, the Jade Emperor thought the cat eat less but did more and its contribution was bigger than the dog. The dog was very angry because the cat won it with a disgraceful lie. Therefore, the dog abused and chased after the cat to bite it. The cat knew that it was in the wrong, so it kept running and dared not show up even in the home, hiding from place to place.
In selecting the twelve Chinese zodiac signs, however, the heavenly officers didn't follow the Jade Emperor's decree and they changed the rule: those first arrived animals would be the twelve Chinese zodiac signs.
The dog learned the news, so it came with the rooster to the Heavenly Palace when the cat was hiding away from it. The rooster flied to the front of the dog; the cat went out after the dog left and it learned that the dog had gone to the Heavenly Palace to participate in the competition of Chinese zodiac signs. So, the cat ran to the Heavenly Palace in a hurry and ranked after the rooster. Unexpectedly, the rat played a trick and hid in the ox's horn, thus ranked first among the animal signs while the cat had no chance. From then on, the cat hated the rat and killed rat whenever it found one. Although the honest dog was selected successfully, it never forgave the cat.
Stories of Other Zodiac Animals: