HYPOPLASIA OF THE FUSED FIRST AND 2ND TARSAL BONES IN A STANDARD-BREDTROTTER

Radiographic examination was performed on the tarsocrural, metacarpo- and metatarsophalangeal joints of a la-month-old Standardbred mare. Ra diographs of the left tarsus revealed abnormalities in the bones that constitute the plantarodistal part of the tarsus. Follow-up radiograph ic examinations were performed 7, 12, and 28 months later and revealed similar changes. Periosteal proliferations and lameness were not obse rved. In addition, ununited proximoplantar tuberosity of the proximal phalanx was observed at the left proximal phalanx, and plantar osteoch ondral fragments were observed in both metatarsophalangeal joints. The horse was slaughtered at 2.5 years of age, and necropsy of the tarsi revealed hypoplasia of the left first and second (fused) tarsal bones.