Measurements of body surface area and volume in laboratory rabbits (New Zealand White rabbits) using a computed tomography scanner

Abstract

The body surface area (BSA) of an organism is one of the important parameters 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 the k value by 2/3 of the power of the body weight (BW) (Meeh’s formula). In mathematics, if it is assumed that the density and body shape of the animals are essentially constant, the BSA is proportional to BW2/3. In this study, we measured the BSA and volume (V) of 72 laboratory rabbits (48 males and 24 females of New Zealand White rabbits [NZW]), using a computed tomography scanner. After BSA and V determination, the k value, density, and sphericity were calculated. We analyzed variations in the k value, density, and body shape of laboratory rabbits. The mean k value of the 72 NZW was 11.0. We advocate using Meeh’s formula, as follows, for estimating BSA of laboratory rabbits (NZW): 100 × BSA [m2] = 11.0 × BW [kg]2/3.

Measurements of body surface area and volume in male Japanese White rabbits using a computed tomography scanner: comparison with male New Zealand White rabbits

“…In our previous report [9], we measured the BSA and V of NZW using the same methods as the present study. The mean k value, density, and sphericity of 42 male NZW at 11–41 weeks of age were 11.1, 1.05, and 0.421, respectively (working BW range: 2.22 to 3.69 kg).…”

“…One reason for why the sphericity of JW was smaller is the longer ear and face dimensions of this breed compared to NZW. Furthermore, at 11 to 41 weeks of age, the k value, density, and sphericity of male NZW essentially remained constant [9], whereas in the case of male JW, only sphericity remained constant; the k value was negatively correlated with BW while density was positively correlated with BW. Therefore, as the BW of male JW from 10 to 54 weeks of age increased, the k value and density approached the values of NZW.…”

“…The BSA was measured as described previously [9]. Briefly, the body of each rabbit was set in the prone position for whole-body CT scanning on the day of euthanasia.…”

“…Additionally, Bai et al reported 7-month old male JW (working BW range: 2.5 to 3.0 kg) k values of 11.30 to 11.35 determined by use of paper cover and skinning [1]. However, it has been pointed out that the BSA computed by Zehnder’s procedure may be smaller than the actual value [9] and that the accuracy and reproducibility of other traditional methods may have limitations [7].…”

“…CT scanners can generate detailed 3-dimensional (3D) images of objects, thus, with appropriate analysis, CT images provide more accurate BSA estimates than traditional measurement techniques. Previously, we determined the BSAs of laboratory miniature pigs and NZW using a CT scanner and 3D analysis software based on the computer graphics algorithm known as Marching Cubes and Discriminant Analysis Method, and calculated the k values for peripubertal- or mature-miniature pigs, juvenile miniature pigs, and NZW as 7.98 [7], 8.58 [8], and 11.0 [9], respectively. Unlike the traditional measurement techniques, analyzing CT images does not depend on the skill of an operator, thus, the results are extremely reproducible.…”