OBJECTIVE: To develop equations for prediction of total body water (TBW) content in unsedated dogs by combining impedance (resistance and reactance) and morphological variables and to compare the results of those equations with TBW content determined by deuterium dilution (TBW(d)). ANIMALS: 26 healthy adult Beagles. PROCEDURES: TBW content was determined directly by deuterium dilution and indirectly with equations developed from measurements obtained by use of a portable bioelectric impedance device and morphological variables including body length, height, weight, and thoracic and abdominal circumferences. RESULTS: Impedance and morphological data from 16 of the 26 dogs were used to determine coefficients for the following 2 equations: TBW(1) = -0.019 (BL(2)/R) + -0.199 (RC + AC) + 0.996 W + 0.081 H + 12.31; and TBW(2) = 0.048 (BL(2)/R) + -0.144 (RC + AC) + 0.777 W + 0.066 H + 0.031 X + 7.47, where AC is abdominal circumference, H is height, BL is body length, R is resistance, RC is rib cage circumference, W is body weight, and × is reactance. Results for TBW(1) (R(2)(1) = 0.843) and TBW(2) (R(2)(2) = 0.816) were highly correlated with the TBW(d). When the equations were validated with data from the remaining 10 dogs, the respective mean differences between TBW(d) and TBW(1) and TBW(2) were 0.17 and 0.11 L, which equated to a nonsignificant underestimation of TBW content by 2.4% and 1.6%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that impedance and morphological data can be used to accurately estimate TBW content in adult Beagles. This method of estimating TBW content is less expensive and easier to perform than is measurement of TBW(d), making it appealing for daily use in veterinary practice.
OBJECTIVE: To develop equations for prediction of total body water (TBW) content in unsedated dogs by combining impedance (resistance and reactance) and morphological variables and to compare the results of those equations with TBW content determined by deuterium dilution (TBW(d)). ANIMALS: 26 healthy adult Beagles. PROCEDURES: TBW content was determined directly by deuterium dilution and indirectly with equations developed from measurements obtained by use of a portable bioelectric impedance device and morphological variables including body length, height, weight, and thoracic and abdominal circumferences. RESULTS: Impedance and morphological data from 16 of the 26 dogs were used to determine coefficients for the following 2 equations: TBW(1) = -0.019 (BL(2)/R) + -0.199 (RC + AC) + 0.996 W + 0.081 H + 12.31; and TBW(2) = 0.048 (BL(2)/R) + -0.144 (RC + AC) + 0.777 W + 0.066 H + 0.031 X + 7.47, where AC is abdominal circumference, H is height, BL is body length, R is resistance, RC is rib cage circumference, W is body weight, and × is reactance. Results for TBW(1) (R(2)(1) = 0.843) and TBW(2) (R(2)(2) = 0.816) were highly correlated with the TBW(d). When the equations were validated with data from the remaining 10 dogs, the respective mean differences between TBW(d) and TBW(1) and TBW(2) were 0.17 and 0.11 L, which equated to a nonsignificant underestimation of TBW content by 2.4% and 1.6%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that impedance and morphological data can be used to accurately estimate TBW content in adult Beagles. This method of estimating TBW content is less expensive and easier to perform than is measurement of TBW(d), making it appealing for daily use in veterinary practice.