Sixty-four dogs, both sexes, undefined race, weighing 66 to 18 kg, were utilized. Some animals were used to establish the normal values whereas others were anesthetized by sodium pentobarbital, using 30 and 45 mg/kg body weight. Determinations of the alkaline reserve were made by the Van Slyke-Neill method. The normal value for the alkaline reserve in dogs was 19.00 ±2.11 meq/l. The value for the females was 18.60 ±1.71 meq/l and for males was 19.40 ±2.44 meq/l. Sodium pentobarbital in different dosages was able to increase the alkaline reserve. The time the dogs were under the anesthetic influenced the alkaline reserve.