The keratin in the epidermis, when thickened and cornified, is referred to as [[Horn - Anatomy & Physiology|horn]]. Horn is particularly resistant to mechanical and chemical damage. The outer surface of the hoof is composed of horn.
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The equine hoof is defined in a physiologic as the modified skin covering the tip of the digit and all enclosed structures.
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The keratin in the epidermis, when thickened and cornified, is referred to as [[Horn - Anatomy & Physiology|horn]]. Horn is particularly resistant to mechanical and chemical damage. The outer surface of the hoof is composed of horn.