Abstract
Dermal and epidermal laminar lesions were correlated with acute intestinal, primary hepatic, septicemic, chronic laminar, and acute laminar diseases. Horses with acute intestinal disease had edema in the secondary dermal laminae. Those with hepatic disease had increased keratinization of the secondary epidermal laminae. Septicemia caused increased keratin formation in the primary and secondary epidermal laminae. Chronic laminitis caused architectural changes of the epidermal laminae characterized by hyperplasia and keratin formation of the basal epidermal layer. Horses with acute laminitis had epidermal necrosis, especially with peracute laminitis. Various insults to the epidermal laminae led to epithelial hyperplasia of the secondary epidermis with ventral deviation of the third phalanx.