Abstract
The effects of butorphanol and pentazocine on the circulatory system was investigated in 10 healthy dogs under halothane anesthesia. An injection of butorphanol (0.5 mg/kg) had quite similar effects on the circulatory system to those by an injection of pentazocin (2 mg/kg) . The arterial pressure and respiratory rates were slightly more depressed by butorphanol than by pentazocine. The after-load was diminished due to the reduced peripheral vascular resistance in butorphanol-injected dogs. As a result, the cardiac output was either increased or maintained, and the renal blood flow was also increased in butorphanol group. These results may indicate the safety and usefulness of butorphanol as an analgesic agent in halothane anesthesia.
