Make the litter box inaccessible to your dog by elevating it so that the cat can reach it but not the dog. Be sure your cat is comfortable with where you have elevated the litter box. You can also use a baby gate and the cat can jump over it or leave enough space underneath for the cat to go through. Use a cat door that allows the cat into a room, but not your dog. If you have a small dog that is the same size or smaller then your cat this will not work.
You can teach your cat to use the toilet and never have to use a litter box.
Don't punish your dog if it eats poop.
Professional Pet Sitting Services offered in the Upper to Mid-Pinellas County Area