Flea bites are behind most dog allergies, however. Along with hair loss from licking and biting the irritated areas, signs of flea allergies include itching and redness. For a particularly allergic dog, it may take as little as one flea bite to start an allergic reaction that lingers for days.
While any dog can have allergies, some are more prone to them than others. Treating your dog's allergies may include topical or internal medication, immunotherapy, a change in diet, and avoiding the allergen.
Hair loss in dogs may also be caused by hyperadrenocorticism, or Cushing's disease, a condition caused by the overproduction of the hormone cortisol. Less commonly, it is due to a tumor on one of the adrenal glands.
Medication is available to treat both forms of Cushing’s disease. However, while not commonly recommended, surgery can be done to remove the tumor associated with the adrenal form of Cushing’s disease.
Cushing's disease is more common in dogs 6 years or older. Other signs of Cushing's disease include eating, drinking, and urinating more, as well as having a pot-bellied appearance. Take your dog to the vet if you notice any of these signs.
Some dogs are more prone to baldness than others. Bald spots on the outer ear, chest, back, thighs, or lower neck may appear in greyhounds, whippets, Chihuahuas, dachshunds, and Italian greyhounds, usually after their first year.