Effect of age on minimum alveolar concentration (MAC) of sevoflurane in dogs.

It is well known that the minimum alveolar concentration (MAC) of inhalation anesthetic decreases with increasing age. However, there is limited information regarding the effect of age on MAC in dogs. This study was designed to determine the effect of age on sevoflurane MAC in dogs. MAC was determined in 6 young (2 years old) and 6 old beagle dogs (8 to 10 years old) under artificial ventilation. Anesthesia was induced via mask induction and maintained with sevoflurane in oxygen, and MAC was determined by using a tail clamp method. The sevoflurane MAC for the older dogs was significantly less than that for the younger dogs (1.86 +/- 0.29% vs 2.25 +/- 0.15%, P=0.007). The MAC of sevoflurane is profoundly affected by age in dogs.