A tall rostral hook in a medieval horse premolar tooth.

Development of dental abnormalities due to improper occlusal wear is common among modern domestic horses. This phenomenon often is attributed to jaw conformation. Rostral mandibular hooks may develop in horses with underjet or mandibular prognathism, a condition where the lower jaw protrudes forward, beyond the upper jaw. Less abrasive diet, free of phytoliths and matrix-like plant fibers, also may promote enamel and focal overgrowths of equine dentition. Here we report a rostral mandibular hook in a lower premolar tooth of a medieval horse, found in a spring deposit in Levänluhta, Osthrobothnia, Finland. To our knowledge, this is the first such report from a medieval horse.