Who is the enemy of the Ox?

Ox. The Ox is least compatible with the Tiger, Dragon, Horse, and Goat. Oxen like to be in charge of whatever they do, proving to be leaders with many opinions and much confidence.

Why does the cat hate the Rat Zodiac?

Because the Rat tricked the cat into missing the banquet with the Jade Emperor, the cat was not included and was not aware that the banquet was going on and was not given a year, thus began the antipathy between cats and rats.