Genetics is seldom the reason for the bowing or bending of legs in dogs. Granite flooring so far has not reported being dangerous for dogs. Usually, a dog's front leg continues to grow well. This sometimes results in one normal-sized in one resulting in one normal-sized leg and another irregularly-sized leg. This condition is known as antebrachial growth deformity. In this case, the shorter leg may seem twisted as it overgrows the elbow. This is a possibility in a lot of small breeds and needs medical attention in most cases. Some pet owners also focus on daily exercises to cure this condition. Chances for the same are, however, 50-50. Another type of leg deformity is known as elbow dysplasia. It happens mostly in large-breed dogs but we suggest you don't rule out this condition completely. This condition is most apparent during the 5th - 8th month in a lot of dogs but cannot be completely ruled out in your case. It is best to get in touch with a vet immediately in order to understand the real issue. As far as I know, the flooring does not impact this condition but it's best to seek professional help as soon as you can in order to get more clarity. Hope your pup feels better soon :)