Respiratory depression and apnea induced by propofol in dogs

OBJECTIVE: To determine the maximal i.v. administered dose of propofol that would not induce a serious adverse event in nonsedated dogs. ANIMALS: 6 clinically normal dogs (3 males and 3 females) between 8 and 12 months old and weighing between 8.8 and 11.3 kg. PROCEDURE: Propofol was administered i.v. at an initial dosage of 6.5 mg/kg of body weight at a rate of 20 mg/10 s. Subsequent doses were incrementally increased by 2.5 mg/kg (eg, second dose: 9 mg/kg) and separated by a minimum of 3 days. This procedure was repeated until a dose that induced a serious respiratory, cardiovascular, or neurologic adverse effect was determined. RESULTS: Apnea was determined to be the serious adverse effect for all dogs. Duration of apnea varied between dogs, but increased in a dose-dependent manner at dosages > 14 mg/kg. CONCLUSIONS: Respiratory depression and apnea are the most likely adverse effects induced by i.v. administration of propofol to dogs. Propofol administered i.v. at a rate of 20 mg/kg/10 s induces minimal cardiovascular depression at dosages in excess of the apneic dosage. CLINICAL RELEVANCE: Respiratory depression and apnea should be expected as potential adverse effects after i.v. administration of propofol to dogs, particularly when administered at rapid rates of infusion.