Power Paws non-slip dog socks help keep dogs from slipping on floors, give traction to senior dogs and dogs with hip dysplasia or arthritis. The sizing guide is the best way to give estimates and averages by weight, by breed, and by foot print. Unfortunately, some breeds don't follow the guide, and some have 2 regular paws and 2 hare-footed paws, and some dogs are far from "average", but in general the sizing guide will be very accurate for the majority of paws. Our size guides are based on averages. Many people upon receiving the sock think they need to be the size of the foot to fit, and they forget that they are dealing with socks that need to stretch to stay on. A good fit is snug. You can put a finger in the sock. It will stay in place while playing, walking, climbing stairs. The sock is too small if with your fingers inside to stretch the sock, you can't put it on your dog's foot no matter how much you stretch it. The sock is too large if it flops, falls off, sags.