Dog Won't Eat His Food Only the Cat's Food

Start mixing in some cat food into the dog's dish with his dog food, see if that changes things. Maybe the dog is telling you something else, and that is that he prefers the cat meal to his own.

You can make home made food for your dog. Google homemade dog food to see if this is something you want to do. Is there somewhere you could put the cat's food so the dog cannot reach it? When my toy poodle was doing this, I put the cat food dispenser in the bath tub. My two cats could access it, but Pookie could not. It only took the cats about a day to figure out the change. Moving the food and rinsing the tub before a shower was easy.