The relationship between cats and dogs is known to be a complicated one. They're very different from one another. They have a hard time communicating because of those differences. It's ruff and impurrfect. Sometimes, it can take fear and confusion for cats and dogs to become friends. Sometimes, the dogs are even intimidated by kittens because of their fierceness. And sometimes, when they do finally become friends, cats and dogs almost look ashamed of it.
But all that does not make those friendships any less valid. And it certainly does not make them any less adorable. You just need to give them a minute together, preferably when they are young, and there's a good chance that this cat and dog that you're so worried about hating one another will actually become the bestest of friends.