What do you do when your pets do not like each other?

Our labrador doesn't really like my cats. So, when the cats are out playing, we make sure that Bruce is somewhere else. We had a dog once who hated all animals except dogs. He killed rabbits, chickens, and stray cats. He was very sweet with humans though. We couldn't do anything to stop him even if we already tried everything. What we did was we just take him out for walks then put him in house dog house.