ANALYSIS OF PHYSEAL GROWTH IN DOGS, USING BIPLANAR RADIOGRAPHY

Biplanar radiography was used to study normal growth of the left and r ight radius in 5 Beagles and growth of the left radius alone in 15 add itional Beagles. We explored the applicability of this radiographic me thod in veterinary medicine by measuring the contribution to total rad ius length from each growth plate. Spherical tantalum markers (0.5 mm) were embedded in the proximal epiphysis, diaphysis, and distal epiphy sis of each dog's radius at 10 weeks of age. Simultaneous biplanar rad iographic views were obtained every 4 weeks until skeletal maturity wa s documented. A three-dimensional coordinate system was constructed al lowing for measurement of growth (in millimeters). Resolution of the m easuring system was 0.074 mm. Mean +/- SEM length of the skeletally ma ture Beagle's radius, as measured from proximal epiphyseal bead to dis tal epiphyseal bead, was 95.33 +/- 1.07 mm, The percentage of contribu tion to the total radius length from the proximal and distal growth pl ates was 36.76 and 64.73%, respectively, with 95% confidence interval of 2.29%. The percentage of contribution to radius length from the dis tal radial growth plate increased for each consecutive time segment, w ith the distal radial physis contributing 61.75% from 10 to 14 weeks o f age and increasing to 70.22% from 22 to 26 weeks of age. Significant growth was not observed after 26 weeks of age. The period of most rap id growth was between 10 and 14 weeks of age. Biplanar radiography was accurate and precise in quantifying the relative contribution of the proximal and distal growth plate to radius length in Beagles. The meth od is applicable in veterinary research or clinical medicine for monit oring of axial and angular growth: physiologic, iatrogenic, or patholo gic.