How can I stop my dog from eating the cats hard food

Shouldn't hurt her but still, not dog food. Put your cat food where the dog can't get to it.

A s-cat-terbrain

A dog can go without food for a few days and then will eat when it is hungry. Just stop giving your dog your food and at its normal feeding time give it a bowl of its food. If it does not eat it, take the food away. Then 24 hours later put the bowl of food out for the dog. If it has not eaten it within ten minutes take it away and then 24 hours later put the bowl of food out for the dog again. By now the dog should be happy to eat what it is given.

try giving her puppy chow to eat it is softer and my dog loves it.

The following is advice from the ASPCA
Cat food is higher in protein and fat, which may make it very palatable to dogs, but if you continue to feed your dog only cat food, over time you'll begin to see nutritional imbalances. It's also possible to see gastrointestinal issues, such as vomiting and diarrhea, in dogs who continually eat cat food.
Pet Nutrition Service

There are the slow-down eating bowls that slow down the dog's eating. The bowl's design doesn't allow the dogs to eat their food quickly. It includes both narrow areas and obstacles. Look at this link to see how these types of bowls look like: http://0.tqn.com/d/petsupplies/1/0/1/3/-/-/b1.jpg

The twofruits you should never feed your cat (and make sure your cat never gets toeat) are grapes and raisins. These two fruits can cause major health problemsfor cats such as kidney failure.