If you dog suffers from itchy, irritated skin you may be looking at the reasons that can cause this and what you can do to help improve it. It is often difficult to determine the exact cause of the problem. However common problems include:
It is possible for a dog in mid-life to develop an adverse reaction to a food ingredient, pollen, develop a wheat allergy etc; that they have in the past been ok with.
Looking at food allergies or intolerances, common food intolerances are to wheat, dairy products, soya and beef. Unfortunately there is no such thing as a universal hypo-allergenic food. It can only be hypo-allergenic to the dog, if the dog is not allergic or intolerant to the ingredients it contains. However a diet that contains ingredients that the dog is not intolerant to will solve the problem, providing it is not an allergy to an environment issue such as pollen. The best way to determine this is by exclusion diets.
As a first step feed a food formulated for dogs prone to this type of sensitivity. I.E. One that does not contain the most likely problem ingredients. Choose a food that has a high level of Omega 6 & 3 fatty acids, as these will benefit the skin and coat. Choose a food that has other key ingredients to promote a healthy skin and coat, such as biotin. Consider a herbal blend to promote the skin and coat condition.
Remember that skin irritation can also be seasonal and hormonally driven.