Physiologic effects of anesthesia induced and maintained by intravenous administration of a climazolam-ketamine combination in ponies premedicated with acepromazine and xylazine.
OBJECTIVE
To examine the physiologic and pharmacokinetic effects of a technique of total intravenous anesthesia in ponies.


METHODS
6 healthy ponies.


METHODS
Ponies were premedicated with acepromazine (0.03 mg/kg of body weight, IV) and xylazine (1.0 mg/kg, IV). Two minutes later, anesthesia was induced with ketamine (2.0 mg/kg, IV) followed by climazolam (0.2 mg/kg, IV). Anesthesia was maintained for 120 minutes by an infusion of climazolam (0.4 mg/kg/h) and ketamine (6.0 mg/kg/h). Oxygen (5 L/min) was supplemented. 20 minutes after the infusion was stopped sarmazenil (0.04 mg/kg, IV) was administered. Cardiovascular and respiratory function measurements were taken before and after premedication, and during anesthesia. Plasma cortsol, ACTH, and catecholamine concentrations were used to assess adrenal and pituitary gland function Ketamine and climazolam kinetics were calculated, on the basis of plasma drug concentrations.


RESULTS
There were no significant changes from pre-xylazine values in heart rate, respiratory rate, arterial blood pressure, cardiac index, systemic vascular resistance, or arterial PO2, PCO2, and pH. Plasma cortisol concentration decreased during anesthesia, but plasma ACTH and catecholamine concentrations did not change. Recovery was fairly smooth, but some excitement and ataxia were noted in 2 ponies.


CONCLUSIONS
Ketamine-climazolan infusion appeared suitable for maintenance of anesthesia in ponies, although recovery was not ideal in 2 of 6 ponies.
Animal Health Trust, Suffolk England.
R
R
Bettschart-Wolfensberger
P M
PM
Taylor
J W
JW
Sear
M R
MR
Bloomfield
K
K
Rentsch
S
S
Dawling
D000075:Acepromazine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D000768:Anesthesia, General / Q000379:methods / Q000662:veterinary*; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D014151:Anti-Anxiety Agents; D001569:Benzodiazepines; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D004359:Drug Therapy, Combination; D006339:Heart Rate / Q000187:drug effects; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007262:Infusions, Intravenous; D007649:Ketamine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D008297:Male; D008874:Midazolam / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011292:Premedication; D012119:Respiration / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects; D014991:Xylazine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D014151:Anti-Anxiety Agents; D001569:Benzodiazepines; D002245:Carbon Dioxide; D014991:Xylazine; D000075:Acepromazine; D007649:Ketamine; C035147:climazolam; D008874:Midazolam; D010100:Oxygen