Dogs and Cats Living Together
Dogs and cats are supposedly life-long enemies. Hence the phrase, "fighting like cats and dogs." Having always owned both cats and dogs, I find the phrase and the premise to be far more inaccurate than accurate. Of course, we all know that there are those dogs that will simply chase every cat they see and those cats that will never tolerate a dog. However, it has been my experience that handled correctly, the vast majority of dogs and cats can live together. They may not learn to love each other; but they certainly can learn to tolerate each other's presence. Dogs and cats that are raised with each other typically do fine their entire lives. They may actually accept an animal of another species more easily than one of their own, in that there are fewer fights over dominance and territory.
There are some dogs that should not be kept with cats. Dogs with a strong hunting heritage may always view cats as prey and may never be able to be trusted with any small animals. In addition to hunting dogs, terriers such as Jack Russells and pitbulls are often poor companions for cats. These dogs have an incredibly strong predatory instinct; they chase and attack moving objects without thinking about whom or what the object may be. Cats and other small pets are just too much of a temptation for these dogs.
Other dogs respond less to the animal than the situation and will leave alone a cat that sits still, but chase and attack one that moves. This is especially true of dogs that are kept outside. There is something about being out of the house that really pushes the hunting instinct into overdrive and will often result in even the most docile indoor dog attempting to chase cats once outside. So, one would not want to make the assumption that a cat and dog who tolerate each other indoors will do the same outside. The dog may decide to attack the cat. Finally, dogs that have a history of attacking cats are likely to do so again and should not be trusted with cats. If you are planning on rescuing a previously-owned dog, it is a good idea to get a history of the dog's attitudes and behaviors around cats before bringing it into a house with cats. Many shelters will allow you to 'test' the dog by introducing it to a cat before completing the adoption.
Most cats, if they have had positive experiences with dogs, will tolerate canines in the house. Those that will not typically have had some prior negative interaction that is firmly embedded in their memories. Because most cats, even those that hate dogs, do not attack without provocation, these cats may be able to live with a dog. However, they probably will never bond with the dog, will avoid the dog at all costs, and will be pretty miserable. It is kinder to leave these cats in a feline-only household. Again, it is often possible to find out the history of a cat before adopting it, or to test the cat's reactions to dogs in an adoption situation.
So which cats and dog can get along? The answer is just about all of the rest of them. In the best of circumstances, cats and dogs really become friends, playing and sleeping together. In other situations, cats and dogs may never be overly friendly, but they can learn to tolerate and behave themselves with other members of the family, including those of other species. As long as you are willing to work out a positive introduction and protect the animals from physical harm, these species usually get along. The process may take up to six or eight weeks, or even longer, but can be successfully accomplished.