Your dog's condition might be caused by poor nutrition. Many commercial dog foods lack essential fatty acids and vitamins such as A, E and B-3 (niacin) . Try a higher-quality dog food or talk to a veterinarian about supplements specifically for healthy skin and coat.
Frequent bathing can cause dry skin. Bathe your dog as little as possible, using a moisturizing shampoo made especially for dogs. Human shampoo is too harsh for dogs because our skin has a different pH [source: Brushing your dog regularly will help him stay clean and stimulate his skin to produce moisturizing oils
You can also try the following home remedies to relieve your dog's dry skin problem:
Add olive oil to his food two or three times a week.
Bathe your dog in a warm water and oatmeal solution.
Apply teat tree oil, fish oil, calendula extract or vitamin E (all available in health food stores) to his skin.
Make sure your dog is well hydrated by providing him with more water, fresh fruits, vegetables and meats, or by adding water to his dry dog food
If nothing helps, or if your dog's skin condition worsens, see a veterinarian to rule out other causes for his dry skin, like mange, infection or ringworm. It may be necessary to treat your dog with prescription medication