Relationship of skin surface area to body mass in the immature rat: a reexamination.

Skin surface area (Ab) was measured in the rat beginning at birth mass and extending over a range of body mass (m) from 5.0 to 49.3 g. Area of each animal was determined using an elastic impression material. The best-fit relationship between Ab and m over the entire range of mass was Ab = 6.88m0.736. Results suggest, however, that the standard mass exponent of two-thirds, for estimating Ab of adult animals, could also be used for immature animals weighing 14 g or more. In rats weighing less than 14 g, the mass coefficient of the Meeh-Rubner equation varies with m, indicating that the two-thirds exponent is inappropriate for use with very young animals.