Common sense indicates that dogs and cats are mortal enemies, as the common phrase "fight like cats and dogs" points out. The truth, however, is that dogs and cats can learn to live together in harmony given the right conditions. In fact, cats and dogs can sometimes get along better than two cats or two dogs living in the same household, because there is no struggle over territory. In the end, it is up to the owner to create a safe haven in which both animals can coexist.

While the majority of dogs do well when sharing a home with cats, some breeds have predatory instincts that will drive them to chase anything that moves. These include terriers, pit bulls, and most hunting breeds. These dogs can be taught to respect cats, but the process will be harder and with fewer chances for quick success.

The best possible scenario is for dogs and cats to grow up together. Introducing them to each other at an early age makes it more likely that they will accept each other's presence. The second best scenario is to bring a dog into a cat's household. Cats tend to be extremely territorial, so it is always better for them to feel comfortable before a dog comes along. If you are adopting an older animal from a shelter, find out as much as you can of its previous history. If the animal experienced abuse or was attacked in the past, it will be less likely to adapt to sharing a household, no matter how docile the companion is.

Whatever the situation, it is important to make sure cats have access to hiding spaces where they can get away from irritating dogs if necessary. This can be an extra room closed with a baby gate, a few empty bookshelves, a windowsill, or even a cat tree. Giving the cat a feeling of security will reduce the chances of confrontation. While dogs and cats may not become friends overnight, patience and consistent work will eventually help them live in harmony.