Common Causes of Your Pet's Persistent Itch
Many pets are allergic to flea saliva. Removing fleas from your pet's environment can help reduce your pet's risk of developing flea allergy dermatitis.
Continuous itching damages the skin, making it more susceptible to yeast or fungal infections. If left untreated, these infections can lead to more serious skin diseases including hot spots. Clean your pet's skin and coat with an antifungal shampoo and use a spray to help soothe the skin from redness and inflammation.
Some pets are atopic, which means their immune system overreacts to allergens including mold, dust, and pollen. Give your pet an antihistamine to help control allergy symptoms, including itching.
It's possible your pet may have hypothyroidism, which can only be diagnosed by your veterinarian through blood tests. Dogs with this condition have an increased likelihood of having skin and allergy problems, causing the skin to become flaky.
A lack of essential vitamins and nutrients may be a cause for itchy, flaky skin. Be sure to give your pet foods that are rich in vitamins and minerals. You can also add a vitamin supplement with Omega 3 fatty acids which may improve your pet's skin health.

If using flea preventatives on your pet, do not skip monthly treatment.