Balding
When dogs begin to lose hair, and it is not the result of parasites (fleas, mites, etc.), trauma or infection, it may be due to a metabolic disorder such as Cushing's syndrome or hypothyroidism.
With Cushings Disease, the adrenal glands secrete an excessive amount of the hormone cortisol. The dogs begin to lose hair on the flank and neck, and many will lose hair on the back and sides of the body. The skin may become thin, scaly and dry, and can also darken in places. Other signs are enlargement of the belly. Typically, a dog with this will want to drink, eat, and urinate more than normal. This disorder is usually treatable.
Hypothyroidism happens when an inadequate amount of thyroid hormone is released to the body. Dogs with this seem to gain weight easily, appear sluggish and seek out warm spots even during the summer months. Hair changes are more noticeable and include loss of hair from the flanks and back, increased pigmentation of the skin, scaling and seborrhea. Because the ears are commonly affected, you'll see a thick greasy, yellowish material inside the canals. To confirm that it is hypothyroidism, a simple blood test is performed. This is treatable with a hormone supplementation.
After these problems have been getting treatment, the hair will begin to grow back.