Body surface area measurement in laboratory miniature pigs using a computed tomography scanner

The body surface area (BSA) of an organism is an important parameter for evaluating physiological functions. In drug development, normalization by BSA is an appropriate method for extrapolating doses between species. The BSA of animals has generally been estimated by multiplying a constant by the power of the body weight (BW). Recently, the use of miniature pigs in non-clinical studies for medical drugs or devices has gradually been increasing. However, verification of their BSA is not as yet sufficient. In this study, we measured the BSAs of 40 laboratory miniature pigs (11 males and 9 females of Göttingen minipig and 14 males and 6 females of Nippon Institute for Biological Science [NIBS] miniature pig) by analyzing computed tomography (CT) images, since measurements using a CT scanner were expected to more precisely determine BSA than classical measuring techniques. The measurement results showed the BSAs of the 20 Göttingen minipigs to range from 0.4358 to 0.8356 m(2) (the working BW range: 12.7-37.0 kg) and 20 NIBS miniature pigs to range from 0.2906 to 0.8675 m(2) (the working BW range: 7.9-41.5 kg). Since accuracy and reproducibility were confirmed by measuring the surface area of an acrylic cuboid, we concluded the measurement method employed in this study to be very reliable. We propose the following estimating formula for BSA of laboratory miniature pigs: 100 × BSA [m(2)] = 7.98 × BW [kg](2/3).