Generally, when dogs itch, it is the cause of parasites, allergies, or some type of bacterial skin infections. Your dog is telling you that there is a medical condition that you need to pay attention to. Itching and continued scratching can result in something more serious. If your dog looks sick or you see any loss of hair, inflammation, or sores, you should take your dog to a vet for the vet to determine what the problem is. If there are no physical signs of illness, I would still recommend that you take the dog to the vet right away.