In one dog show, there was a guest vet who said that dogs should not be given 1) chocolates 2) bones 3) grapes.
With the chocolate, the reason is the caffein in the chocolate that causes the dog to be hyperactive. It might result in cardiac arrest or heart attack. The bone, particularly chicken bone, can harm the throat of the dog when it fails to crush and chew the bone. There are so many cases, according to that vet, that dogs were brought to his clinic with a bone lodged in the throat. But the grapes? I wonder why it affects the kidneys of the dog. There is no further explanation but what can we do but to follow just to be on the safe side.