This is an allergic reaction that most often affects dogs with long coats and dense undercoats. The most common causes for these are insect bites, inhalant allergies, food allergies, burs, anal gland disease, or poor grooming. This occurs when damage to the skin’s surface allows normal skin bacteria to overwhelm the skin’s normal defenses. Very often, the dog will then chew or gnaw at the area that is affected. These present as circular lesions that will be moist, raw, hairless, and painful for the dog. It is one of the most common skin conditions a dog can have and usually happen in the warmer, summer months. The size of the area infected can increase greatly in size in just a few hours. It is easily treated with some topical medicine and grooming.