The hemodynamic effects of rapid intravenous (IV) administration of 10% dextran 40 in saline solution (D40) and 7.2% hypertonic saline solution (HSS) in calves were compared. Calves received isotonic saline solution (ISS), HSS or D40 (3 calves/group) and were monitored of blood pressure, and cardiac output (CO) for 180 min. HSS and D40 infusions induced a significant increase in relative plasma volume reaching 134.9 กพ 2.8 and 125.0 กพ 1.9%, respectively at the end of fluid infusion. In the HSS group, CO, cardiac index (CI) and stroke volume (SV) remained constant at low levels after 90 minutes despite the maximal values of CO, CI and SV at the end of infusion, reaching 21.0 กพ 6.3 l/min (p<0.05), 177.8 กพ 14.2 ml/min/kg (p < 0.001) and 0.20 กพ 0.03 l/beat (at t = 10 min, p < 0.001), respectively. In contrast, CI and SV in the D40 group showed significant increases to 14.7 กพ 2.9 l/min and 153.5 กพ 17.2 ml/min/kg, respectively, at the end of fluid infusion. And those values remained constant at higher levels than those of the before infusions values throughout the experimental periods. Positive effects for hemodynamic alternations of D40 in calf practice were milder and longer than those of HSS. Therefore, the D40 infusion should be explored as a possible treatment for dehydrated calves, since rapid infusion of D40 may be safe and more beneficial for rehydrating more than HSS treatment.