The hock as a potential site for non-invasive bone measurement.

An in vitro study on the calcaneus of adult horses (n = 5) and foals (n = 10) was carried out using radiographic photodensitometry, single photon absorptiometry, transmission ultrasound velocity and chemical analysis. Data for trabecular bone content, ash, calcium and phosphorus levels were obtained. As techniques for assessing bone quality, ultrasound velocity was not sufficiently sensitive nor accurate and radiographic photodensitometry was found to be limited value. Photon absorptiometry was both accurate and reproducible, although some variation in bone mineral content and bone mineral density was observed along the length of the calcaneus. Bone mineral content was estimated in a second series of fibular tarsal bones from 23 horses ranging in age from less than six months to 16 years. The photon absorptiometry technique was also applied to the hocks of four hind limbs at post mortem and two horses under general anaesthesia. It was concluded that the calcaneus was a feasible site for photon absorptiometry, but that the present equipment would require considerable modification for use in the standing horse.