To use CT measurements to define the body surface area (BSA) formula in American bullfrogs (Lithobates catesbeianus) and calculate the species-specific shape constant (K) to suggest chemotherapeutic doses.
12 American bullfrogs owned by the North Carolina State College of Veterinary Medicine Department of Laboratory Animal Resources underwent CT scans without anesthesia or sedation in November 2022.
As part of this prospective study, each American bullfrog underwent a complete physical exam and CT scan. 3-D surface models were created using CT data, and the resulting measurements were used for BSA calculations. Animals were grouped by sex. Nonlinear regression analysis of BSA versus body weight was performed, and a species-specific formula was derived for calculating BSA in American bullfrogs.
The mean body weight of the bullfrogs was 354 grams. The mean CT-derived BSA was 414.92 cm2. The calculated K constant was 8.28 for the 12 American bullfrogs, and the CT-derived BSA formula was BSA in cm2 = 8.28 X (body weight in g)2/3. The K constant was 8.07 for females and 8.44 for males and was not significantly different between sexes (P = .5).
Results indicated that the species-specific K constant for American bullfrogs is 8.28. This is the first calculated K constant that exists for amphibians to our knowledge.
To determine the K-constant for body surface area calculation from body weight in corn snakes (Pantherophis guttatus) through the use of computed tomography (CT) measurements.
12 adult corn snakes held by North Carolina State University for research purposes underwent CT between November 2022 and January 2023.
Each snake had a CT scan, physical examination, and body weight measurement. CT images were uploaded into software able to perform 3-D reconstruction and measure body surface area. The species-specific K-constant was determined using nonlinear regression analysis between body surface area and (body weight in grams)2/3.
The mean body weight of the 12 adult corn snakes was 228 g, with a mean body surface area of 505.1 cm2. The calculated K-constant was 13.6 (P < .001). The resulting formula for body surface area in corn snakes is BSA in cm2 = 13.6 X (body weight in grams)2/3.
The body surface area formula developed for corn snakes will allow for improved dosing accuracy for medications with low therapeutic safety margins. Additional pharmacokinetic and pharmacodynamic studies are necessary to determine the safety and efficacy of individual medications.