This is a genetic defect affecting the way pigment is distributed in the hairs of affected dogs. Dogs with unusual haircoat coloration such as blue or fawn are affected. Abnormal pigment (melanin) clumping in the hairshafts and subsequent changes in light refraction are responsible for the unusual coloration, and in severely affected animals, excessive pigment clumping causes breakage of the hairshafts and abnormal or stunted hair growth.

Dogs with blue or fawn haircoats. Doberman pinschers are often most severely affected, but it can occur in any breed. Color dilution alopecia does not occur in all dogs with blue or fawn coats, and the frequency varies within affected breeds.

Hair breakage and hair loss in color dilute areas usually begin in late puppyhood or young adulthood and may progress to total hair loss over several years. The underlying skin is normal, but the hair follicles often become occluded with skin cells and fragments of broken hairs, leading to secondary bacterial skin infection/folliculitis. There is usually no itching unless a secondary skin infection occurs, and there are no systemic signs of illness.