Young puppies are curious about cats and may want to chase or play, but do not want to injure the cat. The cat will swat and hiss, and the puppy will learn to set boundaries. The puppy is bound to get a scratched nose before it's all sorted out, but will learn to inhibit his playfulness to however much the cats will tolerate. It's better for the cat if it maintains some level of fear or dislike for dogs, so it will flee or swat if the dog gets rough. The high prey drive in one of my greyhounds was not known when I adopted her, because she was feeling insecure. After many months in her new home, her true nature emerged. Unfortunately, my cat had no fear of dogs, and loved to weave through their legs, rubbing against them and purring. One day, out of the blue, the greyhound, in a matter of a second or two, grabbed her as she hopped off a chair, shook her, and broke her neck, then looked disappointed that the cat wasn't moving anymore. Had the cat ever scratched the dog, the dog would likely have had some respect and kept her distance from the cat.