Article: No matter how badly you want your dog and cat to love each other, you may never get them to do anything but tolerate each other. If they are already at odds, even that may not be realistic. First impressions are crucial to helping a dog and a cat live together in harmony, and once they've taken a dislike to each other it is very hard to reverse the relationship. Some of the methods described above could be used with animals already living in the same home, but it is important to remember that you cannot change an animal's nature, and you cannot force two animals to be friends any more than you can force two humans. This is the most important facet of keeping the peace between dogs and cats. Allowing your dog to discover how fun it is to chase cats will give her positive reinforcement for behavior you do not want, and make her much more difficult to train. It will also make your cat see your dog as a thing to be feared. Be firm and consistent, and make sure your dog obeys "leave it" without hesitation. Until you are positive beyond a shadow of a doubt that they can be trusted, never leave a cat and a dog alone together. An altercation between them while you are gone could undo all the progress you have made. Always err on the side of caution if you are not 100% certain. Forcing them to interact will only cause your animals to associate being around each other with unpleasant feelings, and make them more likely to lash out. If you are tense and on-edge, your animals will sense it, and it will make them nervous as well. Keep cool, and if you, your dog, or your cat become upset, separate your animals and come back to training when you are all calm. A cat doesn't understand the concept of a leash, and keeping your dog restrained will not necessarily make the cat feel any more at ease. An animal that feels trapped is a desperate animal, and if the cat does not feel he can get away to a dog-free area, he may lash out or flee.

What is a summary?
Have realistic expectations. Prevent your dog from chasing your cat. Supervise all interactions. Respect your pets' boundaries. Stay calm. Make sure the cat never feels trapped.