This article provides a brief review of human episcleritis and scleritis, because the pathogenesis, diagnosis, and treatment of these disorders are perhaps the best understood of all species of animals. The clinical and light microscopic manifestations, therapeutic options, and prognosis for primary and secondary episcleritis and scleritis in dog are also reviewed. The focus of this article is on primary and secondary inflammatory conditions that originate in the episclera and sclera caused by idiopathic or known etiologies.