Its a old saying " to fight like 'cats and dogs" . I remember as a kid having a dog but NO CATS .
My grandfather HATED cats. He always said that a dog and cat could never live together peacefully. Naturally , that prompted me to prove him wrong. Years later, Ive succeeded. Granted it didn't happen overnight. It took alot of work to "un-train" the natural prey drive out of Bowser, but he got it. Now, both of my cats share space with the dog and things could not be more harmonious in the house. They sometimes even share water bowls and often drink at the same time.
If you already have a dog or a cat and are thinking about adopting the 'enemy".. let this go to show that with a little work its definitely possible to live happily in the same house with a dog and a cat. They can even become friends ! Good Luck ~ and remember ADOPT DONT SHOP