DISTAL LIMB SWELLING AND PERIOSTEAL PRODUCTIVE REACTION IN PERIPARTURIENT SICHUAN TAKIN (): FIVE CASES OF PRESUMPTIVE HYPERTROPHIC OSTEOPATHY.

Hypertrophic osteopathy, a syndrome characterized by painful distal limb swelling and proliferative periosteal reaction, primarily involves the metacarpal and metatarsal bones and phalanges. Lesions are often bilaterally symmetric and typically affect all four limbs. Hypertrophic osteopathy is frequently associated with primary intrathoracic disease, though this condition has also been reported secondary to intra-abdominal and intrapelvic disease and associated with pregnancy in both people and horses. Over a 20-yr period, five adult female Sichuan takin (), with 13 total pregnancies, were evaluated because of lameness and distal limb swelling. These clinical signs were observed between 2 and 32 days (mean = 19 days) prior to parturition (gestation period in takin approximately 200-240 days) and resolved in all animals following parturition. Lameness and limb swelling resolved between 8 and 168 days (median = 15 days) after parturition. Sixteen radiographic examinations, from four of the individuals, documented proliferative periosteal reaction, primarily of the metacarpal bones, metatarsal bones, and phalanges. The clinical progression, resolution of signs, and radiographic features in these cases are consistent with hypertrophic osteopathy, secondary to pregnancy. This is the first report describing presumptive hypertrophic osteopathy in takin.