It is highly likely that your dog has dermatitis, an inflammatory condition of the skin. This can be caused by numerous things. Dermatitis can be a very frustrating problem to treat for both owners and often vets too!
One very common cause is fleas. This can be the case even if you cannot see or find fleas. In some cases, dog can have allergic reactions from just one bite of ONE flea! So ensure your dog is on a good flea treatment. See PawClub Health and Care for more information.
Itchy skin can also be caused by certain types of mites. These need to be diagnosed by your veterinarian, often after performing skin scrapings and examining them under a microscope.
Alternatively, itching may be the result of a bacterial or yeast infection. These infections can be the cause of the itching on their own or may be due to additional problems as well. Your vet may want to do a sticky tape preparation to diagnose the infection. Depending on what is found your dog may need to be given antibiotics or antifungal medications.
Many dogs suffer from itchy skin at certain times of the year. This can be due to allergies to pollens or other triggers in the air at that time of year. These allergens are breathed in and cause the itchy skin. It is similar to hayfever in humans, except instead of red eyes and runny noses, we see itchy skins in our dogs.