Mange
Mange is a skin disease that occurs when tiny mites overpopulate the skin, causing irritation. All dogs have some mites on their skin, but during times of high stress, these mites will multiply uncontrollably. Mange can cause patchy hair loss and scaly skin that can be extremely itchy.
Trauma
Depending on the type of trauma, your dog can experience hair loss if they continually lick a specific area. This is called acral lick dermatitis and many dog owners will notice persistent licking of one area that results in skin irritation, skin lesions and hair loss.
Allergic Reaction
Allergic reactions can occur from a variety of sources including food, chemicals, plants and external parasites. Hair loss and extreme itching can occur from certain allergic reactions especially food allergies where the allergic reaction is not diagnosed immediately and the symptoms are more subtle.
Infection
Skin infections can cause red, inflamed skin that is itchy and hair loss can occur. Infections include ringworm, yeast, folliculitis and bacterial. Pus and/or hot spots are usually good indicators that an infection is present.
Hormonal Imbalance
Hormones play a large part in healthy skin and hair, when your dog is experiencing problems with their hormone levels you may notice itching and hair loss. Thyroid and adrenal gland deficiencies can cause problems for your dog, especially hair loss.
Mites or Parasites
There are mites that can cause scabies, a contagious infection that can be spread to humans. Scabies will cause intense itching and possible hair loss from the scratching. Fleas can also cause your dog to experience intense itching when they bite. It is important to treat your dog for fleas as soon as you see the first sign of fleas.