HEMODYNAMIC AND ANALGESIC EFFECTS OF PROPOFOL INFUSION IN MEDETOMIDINE-PREMEDICATED DOGS

Hemodynamic and analgesic effects of medetomidine (30 mu g/kg of body weight, IM), atropine (0.044 mg/kg, IM), and propofol (2 mg/kg, IV, as a bolus, and 165 mu g/kg/min, IV for 60 minutes, as an infusion) were evaluated in 6 healthy adult Beagles. Catheters were placed while the dogs were anesthetized with isoflurane in oxygen. Administration of i soflurane was then discontinued, and dogs were allowed to breath oxyge n until end-tidal isoflurane concentration was less than or equal to 0 .5%. At this time, baseline measurements were recorded and medetomidin e and atropine a ere administered. Ten minutes later, the bolus of pro pofol was given and the infusion was begun. Analgesia was evaluated wi th a tail clamp test and by use of a direct-current nerve stimulator. Sinoatrial and atrioventricular blockade developed in all 6 dogs withi n 2 minutes of administration of medetomidine and atropine, but disapp eared within 10 minutes. Apnea did not develop after administration of propofol. Analgesia was strong and consistent throughout the entire 6 0-minute period of propofol infusion. Medetomidine significantly (P < 0.05) increased systemic vascular resistance and decreased cardiac out put, compared with baseline values. Propofol infusion appeared to alle viate medetomidine-induced vasoconstriction. Recovery was smooth and u ncomplicated. Ah dogs were able to walk normally at a mean time (+/- S EM) of 88.2 +/- 20.6 minutes after termination of propofol infusion. I t was concluded that medetomidine, atropine, and propofol, as given in the present study, is a safe combination of anesthetic drugs for use in healthy Beagles.