MEASUREMENT OF BONE-MINERAL CONTENT TO FACILITATE AN OBJECTIVE EVALUATION OF LIMB FUNCTION IN THE DOG - A FEASIBILITY STUDY USING DUAL-PHOTON ABSORPTIOMETRY

The aim of this study was to evaluate the feasibility of using measure ments of bone mineral content (BMC) and bone mineral density (BMD) by dual photon absorptiometry (DPA; Gadolinium-153), as an objective meas ure of limb functional status in the dog. The in vitro accuracy error expressed as the standard error of the estimate (SEE) for BMC and BMD measurements was 3.2% and 1.1% respectively, and the precision in vivo for measurements of BMC and BMD in the distal diaphysis of the tibia and fibula was 2.1% and 1.9% respectively. A significant difference in bone mineral between right and left leg was not found in normal dogs, and in these dogs the average percentage intra-individual difference, between bone mineral in the legs with the highest bone density and th e legs with the lowest density, was 2.2% and 3.7% for BMC and BMD resp ectively. However the BMC and BMD in eight clinical cases of unilatera l lameness were significantly decreased in the affected legs, when com pared to the healthy contralateral legs, by 20.4% (P = 0.01) and 18.3% (P = 0.01) respectively. Measurements of BMC and BMD by DPA in weight -bearing extremities in the dog showed that bone mineral is highly sen sitive to decreased loading of the extremity. This method might well b e used not only as an objective measure of limb activity, but also for measurement of prospective changes in bone mineral, following treatme nt of musculoskeletal diseases and injuries.