Demodectic Mange

• According to Pawprints & Purrs, demodectic or demodex mange is caused by the demodex mite. This mite is found on nearly every dog. It does not ordinarily cause problems, but the mite can cause mange in dogs that have immune system issues or a genetic susceptibility. The symptoms are red, scaly skin, hair loss and excessive itching. The hair loss may occur in patches, and in this case it is called localized mange. If it occurs all over the body, it is called generalized mange. The veterinarian will treat your dog using a medicated dip. He may also recommend an antibiotic if the dog has a secondary skin infection from scratching.
  
  

Sarcoptic Mange

• Mar Vista Vet explains that sarcoptic mange is also caused by a mite, but rather than living on the surface of the skin like the demodex mite, the female Sarcoptes scabei mite tunnels below the skin to lay her eggs, which causes red, scaly skin, extreme itching and hair loss. A veterinarian can diagnose the disease by examining a skin sample under a microscope. The disease can be treated in most dogs using Ivermectin, Revolution or Moxidectin.
  
  

Malassezia

• Malassezia is a yeast infection that is common in dogs. The symptoms are redness, hair loss and oily or scaly skin. The dog may also have an unpleasant odor, according to Pet Education. It can be diagnosed by taking a skin scraping or swabbing and examining it under a microscope. The veterinarian may prescribe a medicated shampoo or an anti-fungal medication to treat the skin condition.
  
  

Atopic Dermatitis

• Atopic dermatitis is caused by allergies. The symptoms of allergic dermatitis, according to Family Vet, are itching, redness and hair loss from excessive scratching. Since this is an allergic reaction, the dog may also exhibit other allergy symptoms such as sneezing or coughing. The best option is to avoid the allergen, but since this is not always possible, the veterinarian may prescribe an antihistamine or place the dog on a hypo-allergenic diet.
  
  

Flea Bite Allergy

• Dogs can develop an allergy to being bitten by fleas. The symptoms of a flea bite allergy are redness, itching, flaky or scaly skin, and localized hair loss, especially around the base of the tail. Pet Education recommends treating the dog using an insecticide that is designed to kill adult fleas, as well as an insect growth regulator that will kill juvenile fleas. The website also recommends sanitizing the dog's environment to prevent any flea eggs from hatching.