Evaluation of the oral 13C-bicarbonate technique for measurements of energy expenditure in dogs before and after body weight reduction

Abstract

BackgroundOverweight and obesity are the most common nutritional disorders in dogs and may lead to various secondary diseases and decreased lifespan. In obesity research, measurement of energy expenditure (EE) and determination of the energy requirements are essential. The objective with this study was to validate and evaluate the suitability of the oral 13C-bicarbonate technique (o13CBT) for measuring EE in dog obesity studies. A further objective was to investigate the impact of body weight (BW) reduction and changes in body composition on the EE when measured under conditions corresponding to the basal metabolic rate (BMR).ResultsThe EE in five privately owned, overweight dogs was measured simultaneously with the o13CBT and indirect calorimetry (IC) for comparison of the results. Two measurements per dog were performed under the same standardised conditions (i.e. fasted and resting state) at the start, and after completing a 12-week BW reduction program. Additionally, measurements of body composition by Dual-energy X-ray absorptiometry (DEXA) were conducted at the beginning and at the end of the BW reduction program. There were no differences in EE results obtained by the o13CBT and IC. Overweight and the BW reduction did not affect the estimates for the respiratory quotient (RQ) or the recovery factor for the 13C-tracer (RF), both needed when using the o13CBT. The dogs lost 16% (SD ± 2.0) of their initial BW in reduced fat mass (P < 0.001), whereas fat free mass (FFM) remained unchanged. There was no effect of the BW reduction on the determined EE expressed in kJ/kg BW/d, or in kJ/kg BW0.75/d. However, EE was lower (P < 0.001) after the BW reduction program when expressed in relation to FFM (kJ/kg FFM/d).ConclusionsResults from the present study show that the o13CBT can be a used in obesity research to determine EE in fasted dogs and under resting conditions. Furthermore, the results suggest that the BMR does not change with reduced BW in overweight dogs as long as the FFM remains unchanged. This indicates that the BMR to maintain one gram of fat is equal to maintaining one gram of FFM in overweight dogs.

Validation of the 13C-bicarbonate tracer technique for determination of CO2 production and energy expenditure in ponies by indirect calorimetry

“…It is well known that the recovery of 13 C is not complete, and in studies using IV administration of 13 Cbicarbonate the RF in breath CO 2 has been found to be 0.73 in young bulls (Junghans et al, 2007), 0.72 in goats (Prieto et al, 2001), and in studies with oral administration the RF was found to be 0.69 in humans (Junghans et al, 2008) and 0.72 in dogs (Larsson et al, 2014). In this study there was a significant difference between the two administration routes with a RF of 0.690 for IV and 0.760 for oral administration.…”

“…Junghans et al (2007) used oral administration of 13 Cbicarbonate dissolved in water to humans and obtained satisfactory results when comparing the 13 C-BT to IC. In a study in dogs it was found that oral administration of 13 Cbicarbonate could be used to assess reliable estimates of EE (Larsson et al, 2014). In those two studies it was probably easier to control that the entire dose reached the stomach, as the humans drank a water solution with the dose and the dogs swallowed the dose mixed with a small amount of meat.…”

“…The 13 C-BT method is based on 13 C kinetics in breath or blood CO 2 after administration of 13 C labelled sodium bicarbonate (NaH 13 CO 3 ), where the ratio between the 13 C and 12 C in samples of expired CO 2 can be used as a measure of the CO 2 production rate (Elia, 1991). The 13 C-BT has been used to determine EE in cattle (Junghans et al, 2007;Kaufmann et al, 2011), goats (Prieto et al, 2001), dogs (Larsson et al, 2014) and humans (Junghans et al, 2008) with success. Oral administration of 13 C-bicarbonate in a single bolus has been used by Junghans et al (2008) and Larsson et al (2014) in humans and dogs, respectively, making the 13 C-BT non-invasive.…”

“…The 13 C-BT has been used to determine EE in cattle (Junghans et al, 2007;Kaufmann et al, 2011), goats (Prieto et al, 2001), dogs (Larsson et al, 2014) and humans (Junghans et al, 2008) with success. Oral administration of 13 C-bicarbonate in a single bolus has been used by Junghans et al (2008) and Larsson et al (2014) in humans and dogs, respectively, making the 13 C-BT non-invasive. Urschel et al (2009) used 13 C-bicarbonate to determine CO 2 production in horses for calculating the rate of amino acid oxidation, and found continuous intravenous infusion of 13 C-bicarbonate to give better estimates than frequent oral administration.…”

Gut microbiota composition may relate to weight loss rate in obese pet dogs

“…Results from this intervention have previously been published regarding effects on body composition, immunometabolic parameters, gene expression and energy expenditure (Larsson et al . ; Herrera Uribe et al . ; Vitger et al .…”