This study aims to compare and describe the tidal volume (Vt) utilized in mechanically ventilated dogs across different body condition scores (BCSs). Ninety dogs requiring mechanical ventilation (MV) were categorized into three groups based on their BCSs ranged from 1 to 9: Group I (underweight, BCS 1∼3, n=26), Group II (ideal weight, BCS 4∼6, n=48), and Group III (overweight, BCS 7∼9, n=16). The median Vt for each group was recorded, and the differences were analyzed under the same median driving pressure. The median Vt was found to vary significantly among the groups. In particular, the K value for Group I (underweight) was 23.6 (9.1∼44.7) mL/kg, that for Group II (ideal weight) was 17.7 (10∼36.6) mL/kg, and that for Group III (overweight) was 10.9 (6.2∼13.1) mL/kg. The Vt used in Group III was significantly lower than that in Group I. The findings indicate that underweight dogs are ventilated with a higher Vt than ideal weight and overweight dogs, while overweight dogs require a lower Vt than ideal weight dogs to achieve adequate alveolar ventilation.