BackgroundThe effects of inhalational anesthetics on the hypoxic ventilatory response are complex. This study was designed to determine the contribution of peripheral chemoreception to the depression of hypoxic ventilatory response seen with halothane anesthesia.MethodsCats were anesthetized with pentobarbital sodium and [Greek small letter alpha]‐chloralose and artificially ventilated. Respiratory output was evaluated by phasic inspiratory activity of the phrenic nerve. In 12 cats, this activity was measured during inhalation of an hypoxic gas mixture with halothane, 0, 0.1, and 0.8%, with intact or denervated carotid bodies. In 10 cats, a carotid body was isolated from the systemic circulation and perfused with hypoxic Krebs‐Ringer solution equilibrated with halothane, 0, 0.1, and 0.8%.ResultsThe hypoxic ventilatory response was depressed in a dose‐dependent manner during halothane anesthesia. In carotid body perfusion studies, the response was significantly depressed only with halothane, 0.8%.ConclusionThe hypoxic ventilatory response is depressed by a high dose of halothane through a peripheral effect at the carotid body.