We can’t affirm whether you feed your Great Dane a proper diet or not. The food such as Avocados, Onions, Garlic, cocoas, chocolate, tea, coffee, raisins, Grapes, chewing gums, candies, salt, salty foods, sugar, sugary foods, sugary drinks, persimmons, peaches, macadamia nuts, plums, liquor, wine, beer or any food cooked in alcohol, leftover food, table scraps, or any food that have a high content in fat or heavily or extra seasoned food, etc. is harmful to Great Danes health.