Hemodynamic and analgesic effects of medetomidine (30 micrograms/kg of body weight, IM), atropine (0.044 mg/kg, IM), and propofol (2 mg/kg, IV, as a bolus, and 165 micrograms/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 isoflurane was then discontinued, and dogs were allowed to breath oxygen until end-tidal isoflurane concentration was < or = 0.5%.
At this time, baseline measurements were recorded and medetomidine and atropine were administered. Ten minutes later, the bolus of propofol was given and the infusion was begun.
Analgesia was evaluated with a tail clamp test and by use of a direct-current nerve stimulator.
Sinoatrial and atrioventricular blockade developed in all 6 dogs within 2 minutes of administration of medetomidine and atropine, but disappeared within 10 minutes.
Apnea did not develop after administration of propofol.
Analgesia was strong and consistent throughout the entire 60-minute period of propofol infusion. Medetomidine significantly (P < 0.05) increased systemic vascular resistance and decreased cardiac output, compared with baseline values.
Propofol infusion appeared to alleviate medetomidine-induced vasoconstriction.
Recovery was smooth and uncomplicated.
All dogs were able to walk normally at a mean time (+/- SEM) of 88.2 +/- 20.6 minutes after termination of propofol infusion.
It 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.
Source: Thurmon JC, Ko JC, Benson GJ, Tranquilli WJ, Olson WA (1994): Hemodynamic and analgesic effects of propofol infusion in medetomidine-premedicated dogs. In: Am J Vet Res. 1994 Mar;55(3):363-7.
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