I agree with getting your dog on a good feeding schedule. Teach her that when food is offerred it must be eaten. If she hasn't eaten it within a reasonable time frame then the food is put away and not offerred until the next feeding time.
Not only will this be good for keeping the cats out of the dog food, it will be good for in the future if Kitana is ever sick. Some of the first questions a vet will ask you will be when was the last time she ate, how much etc. It is hard to answer those questions sometimes if the food is always just out.

Also it is very important that she is kept from the cat's food. Cat food is much higher in protien than dog food and can do damage to the dog's kidneys over time. I've also heard of dogs having seizures after eating too much cat food. Is there a way you can feed the cats in a place she can't get to, for example in another room, on top of the washer or dryer etc.