I fell into this trap when my Whippet, Sasha, once barked at Tisha, my Australian Cattle Dog. It was an attempt to make the larger dog surrender a juicy rawhide chewy. The next day Sasha barked again, but not at Tisha. I never repeated that chewy-switch, but Sasha has never forgotten it. Their independent thinking, necessary for their original work of hunting game, presents a special challenge to owners seeking Obedience titles for their dogs.
Whippets learn quickly but bore easily with repetition.
Harsh physical or verbal corrections make them shut down. Some Whippets actually seem to learn by observing other dogs being trained. One Whippet I know watched his owner training her Dobie to retrieve a dumbbell. Despite their good qualities, Whippets aren't the perfect breed for everyone. Not if you want a big dog or a tiny dog, or a dog with lots of hair, or a dog that bounces from your walls and swings from your ceiling fans, or one that will do the same obedience exercise over and over again.