Seborrhea is a chronic skin condition that causes excessive scaling and greasiness of the horses skin and coat. It occurs as three different presentations--dryness, excessive greasiness, or scaling and greasiness with local or diffuse inflammation of the horse's skin and haircoat.
Seborrhea is almost always a secondary result from a primary disease, it is rarely a primary disease. The most common primary diseases which cause seborrhea are systemic diseases (pemphigus foliaceus
, equine sarcoidosis, liver disease, nutrition deficiencies, tumors, intestinal malabsorption, toxicosis or imbalances), ectoparasites, bacterial or fungal diseases, and immune-mediated skin conditions. Application of topical products and being stabled with heating can also cause seborrhea.