It is safe for dogs to eat pineapple as a treat. In hot weather, some dogs even like frozen pineapple. Other fruits acceptable for dogs are apples (but not the seeds or core), strawberries, blueberries, seedless watermelon and bananas, which also freeze well.
Certain fruits should never be given to dogs. Ingesting grapes or raisins sometimes leads to kidney failure. Vomiting is often the first indication that these fruits are making a dog sick. Persimmon seeds cause inflammation or obstruction of the small intestines. Whole peaches and plums should not be available to dogs because their pits cause intestinal blockage. In addition, these pits contain the poisonous chemical cyanide.