Dogs large and small: the allometry of energy requirements within a single species.

Dogs are unique among mammals in having a 100-fold range in body weight for nonobese adults. This variation makes the calculation of the power function for metabolic body size and hence the allometry of energy requirements a particularly chal lenging subject. Several functions have been proposed from W068to W088(W = body weight in kg). In the present study we measured the heat output of 22 dogs representing seven breeds, aged 1-10 y with W from 5.8 to 48.8 kg, using a whole-body calorimeter specif ically designed for this purpose. Regression of log en ergy output against log Wgave the equation 678 W0'64 (r = 0.96; P < 0.001), which is considered to represent resting energy expenditure (REE)as kJ/d. If estimates of the energy cost of activity are added to REE, new equations of 655 W069(low activity) and 643 W073 (higher activity) are obtained, depending on the amount of activity included in the calculation. From these re sults we suggest that the allometry of energy require ments of adult dogs is a function of different exponents for REE and the energy cost of activity. It does not appear to exceed W0-7* and may be nearer to W°-S7. J. Nutr. 121: S18-S21, 1991.