It may help to place a clothes hamper or something else that has holes on top of the cat (so that she is safe, but the dog can see and smell her) and let the dog check her out. This may take the intrigue out of the cat and the dog may not be as interested in her.
Ohio farm girl makes a good point though. My dogs know what is mine and for the most part they resist the tempation of eating anything that belongs to the people. They always wait for me to walk through doors first and then they may come once I tell them to. It has taken a while, and they are both young still (1 and 2 years old) but practice makes perfect. But either way some dogs have such high prey drive, there may not be much you can do.