Abstract
Objective—To evaluate energy expenditure (EE) in dogs by estimating rate of CO2 production (rCO2).
Animals—15 Beagles.
Procedure—Food was withheld for 24 hours, and all dogs received an IV infusion of 13C sodium bicarbonate for 8 hours. Breath samples were collected before infusion and at 30-minute intervals from 4 to 8 hours, and 13C enrichment in breath CO2 was measured, using gas chromatography-isotopic ratio mass spectrometry. Food was withheld from 6 dogs, and rCO2 and O2 consumption were measured, using a conventional indirect calorimeter. The CO2 production and O2 consumption were measured by use of indirect calorimetry in 6 other fed dogs that were injected with 2H2O and H2 18O. Blood samples were collected before tracer injection, 4 hours later, and on days 4, 7, and 11. Deuterium and 18O enrichments in plasma water were determined.
Results—Mean rCO2 measured by indirect calorimetry was 516 ± 34 and 410 ± 16 µmol/kg0.75/min in 6 fed and 6 food-deprived dogs, respectively. The rCO2 calculated from 13C-bicarbonate dilution was 482 ± 30 µmol/kg0.75/min. Mean rCO2 determined by use of the double-labeled water method was 1,036 ± 46 mmol/kg0.75/d. Mean energy expenditure calculated from rCO2 determined by infusion of 13C bicarbonate, indirect calorimetry in fed and food-deprived dogs, and infusion of double-labeled water was 386 ± 39, 379 ± 25, 338 ± 14, and 552 ± 25 kJ/kg0.75/d, respectively.
Conclusion and Clinical Relevance—Energy expenditure calculated by indirect calorimetry in unfed dogs can be considered representative of basal metabolic rate. (Am J Vet Res 2002;63:111–118)
