I once had a neighbor whose dog loved grapefruit!! They had a grapefruit tree and the dog would stand on his hind legs to reach up and knock off the lower fruits with his front paws. And, I had a dog years ago who went blackberry picking with me and he loved the berries. He knew there were thorns on the bushes and would pull his lips back and extend his teeth to grab a berry. He also knew that the black fruits were ready to eat and the red ones weren't.