Two cats are fighting how to stop it?

Not sure as to what the question is, but I will try to answer what I feel the question may be. As a general rule, you need to keep a dog from "play" fighting with your cat. Reason is dogs are just to strong of an animal and may harm the cat even though the intent to harm is not there. Dogs have a tremendous amount of force in their bite and could very easily hurt or even kill your cat while playing. This is a general rule and there are exceptions to that rule. It really has to be decided based on your own experience with your own animals. Remember though, cats and dogs are natural enemies and while the dog may playfully fight with the cat for years on end, there may come the time that the playing turns into a serious nature when the dog reverts back to its normal instinct.