Hip dysplasia is a legacy disease, passed through the genes. Chances are that a loose-hipped dog that mates with another loose-hipped dog will give birth to a dysplastic puppy. It would seem, then, that the solution would be simple: to reduce the incidence of the disease markedly, refrain from breeding two dysplastic dogs. But the difficulty in preventing, as well as treating, hip dysplasia is that not all dogs with hip dysplasia will show signs of the disease. Thus, many seemingly normal dogs are bred together, keeping hip dysplasia within in the gene pool.
Environmental factors also play a role in hip dysplasia. For example, it is well known that obesity is a risk factor for the development of arthritis. In addition, dog food that has been over-supplemented with extra proteins, vitamins and minerals to make puppies grow faster can create orthopedic problems in extremely large breeds of dogs that may lead to hip dysplasia and arthritis.
