Dogs don't hate cats. Animals don't hate. However, dogs are descended from wolves, and they have what is called a "prey drive." The prey drive is excited by small animals like cats and squirrels. When dogs see these small animals, especially when they run away, their prey drive is excited, and they give chase. Some dogs will kill the animal if they catch it. There is nothing wrong with this behavior--it is inborn and natural.
well theres this old chinese myth someone told me how there was this race which every animal competed in and the first 12 would win some real special prize so the dog and cat were like best friends until the dog won in the 12 and well the cat lost so the cat got jealous and the prize was for becoming the chinese calender thing how theres the special animal for each month this the legend way HOPE IT HELPS