A dog harness is best used for either really small dogs, or rather large dogs. The reason we use it for really small dogs is that their necks are rather delicate. If one is not too careful with the small dogs, their tracheas could be injured if the collar is yanked on. The purposes for the harness for the larger dogs are as follows: 1. To keep control of the large dog, especially if he yanks on the collar and tends to drag you. 2. To help lift them into a car or wherever lifting is needed 3. To assist a dog with arthritis or osteoarthritis. 4. To assist the large dog with hip dysplasia. 6. To assist a dog that may have partial paralysis. It is important to pay special attention to the size and material used in making the harness. Some are made of leather, and some of pretty materials. The best support is given by vest and dress harnesses. These are complete apparel for the dog and covers the dog well. It is important to make sure that the fit is correct or it may dig into the dogs flesh and cause further problems.