Grapes can be harmful to dogs, but not all dogs are susceptible. Some dogs eat lots of grapes with no ill effects. The cause is unknown but is suspected to be a fungus in the seed or skin of the grape. Dogs who are sensitive to the fungus experience renal failure quickly. Since it's impossible to tell which grapes have the fungus -- and since dogs' reactions can be deadly -- it's safer not to feed any grapes to dogs.
Dogs need a protein diet, and in their natural state, they do not seek or consume any fruit. So if you give your dog a protein diet, human foods like grains, fruits and veggies are unnecessary.
