Sedative effects of medetomidine and its reversal by atipamezole in llamas.
OBJECTIVE
To determine a dose of medetomidine that will induce sedation in llamas, to assess effects of medetomidine sedation on arterial blood gas variables, and to determine efficacy of atipamezole in reversing medetomidine-induced sedation.


METHODS
Prospective, randomized clinical trial.


METHODS
15 clinically normal adult llamas.


METHODS
9 llamas received various doses of medetomidine (0.01, 0.02, or 0.03 mg/kg [0.005, 0.009, or 0.014 mg/lb] of body weight, i.m.). Heart and respiratory rates and sedative effects were recorded. Using the lowest dose that induced deep sedation, 6 different llamas were used to assess effects of medetomidine on arterial blood gas variables. These same 6 llamas were later given atipamezole (0.125 mg/kg [0.057 mg/lb], i.v.) 30 minutes after medetomidine injection. Heart and respiratory rates, sedative effects, and time from atipamezole injection to standing were recorded.


RESULTS
Sedation began 6.67 +/- 1.15 minutes (mean +/- SD) after medetomidine administration (0.03 mg/kg, i.m.). Arterial blood gas variables measured 30 and 60 minutes after injection were not different from baseline. Llamas that did not receive atipamezole remained recumbent for 91.50 +/- 24.68 minutes. After atipamezole administration, llamas were able to stand in 5.80 +/- 3.27 minutes.


CONCLUSIONS
Medetomidine induced light to deep sedation in a dose-dependent manner in clinically normal llamas. A dose of 0.03 mg/kg induced deep sedation with a short period of analgesia. Atipamezole rapidly reversed effects of medetomidine, and llamas recovered quickly and were soon able to stand.
Waldridge
B M
BM
Department of Large Animal Surgery and Medicine, College of Veterinary Medicine, Auburn University, AL 36849-5522, USA.
Lin
H C
HC
DeGraves
F J
FJ
Pugh
D G
DG
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002161:Camelids, New World / Q000097:blood / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007093:Imidazoles / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D020926:Medetomidine; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D006993:Hypnotics and Sedatives; D007093:Imidazoles; C050701:atipamezole; D002245:Carbon Dioxide; D020926:Medetomidine; D010100:Oxygen