Cats are not small dogs. And your cat's nutritional requirements are not the same as those of a dog. For example, cats require higher levels of protein than dogs. Cats must have the amino acid called taurine in their diet, whereas dogs can actually make their own taurine. A cat eating food deficient in taurine can develop severe heart disease and other health problems. Almost all cat foods now contain added taurine.
Your cat requires a different form of Vitamin A than dogs do. Dogs can use beta-carotene as a source of Vitamin A; cats cannot. Your cat cannot manufacture the fatty acid arachidonic acid and must have it supplemented in her diet; it is not essential for dogs to have this fatty acid in their food.
Essentially, if your cat is to eat a significant amount of dog food, she will be eating a diet deficient in many of her required nutrients. To ensure your cat's optimal health, be sure she eats quality cat - not dog - food.