Canine conjunctivitis and blepharitis.

The eyelids and conjunctiva are immunologically active structures with an extensive presence of blood vessels, lymphatics, and immune cells. Several immune-mediated phenomena can involve these structures either in isolation or in association with systemic clinical features. Immune-mediated blepharoconjunctival diseases are divided into two main categories: primary autoimmune disease in which the disease results from an attack against self-antigens and secondary immune-mediated disease in which the disorder results from exogenous material inducing autoimmune disease. Such causes of secondary immune-mediated disease include infectious agents and drugs. This article reviews the most important autoimmune and immune-mediated eyelid and conjunctival disorders in dogs.