Determination of optimal immobilizing doses of a medetomidine hydrochloride and ketamine hydrochloride combination in captive reindeer.
OBJECTIVE
To establish optimal immobilizing doses of medetomidine hydrochloride (MED) with ketamine hydrochloride (KET) for hand- and dart-administered injections in captive reindeer.


METHODS
12 healthy 6- to 9-month-old reindeer (Rangifer tarandus tarandus). Procedure An optimal dose was defined as a dose resulting in an induction time of 150 to 210 seconds, measured from the time of IM injection until recumbency. Initially, each stalled reindeer was immobilized by hand-administered injection. If the induction time was > 210 seconds, the dose was doubled for the next immobilization procedure. If it was < 150 seconds, the dose was halved for the next immobilization procedure. This iteration procedure was continued for each reindeer until an optimal dose was found. Later the reindeer was placed in a paddock and darted with its optimal dose as determined by hand-administered injection. Adjusting to a linear relationship between dose and induction time, optimal darting doses for each reindeer were predicted and later verified.


RESULTS
The established mean optimal hand- and dart-administered doses were 0.10 mg of MED/kg of body mass with 0.50 mg of KET/kg, and 0.15 mg of MED/kg with 0.75 mg of KET/kg, producing mean induction times of 171 seconds and 215 seconds, respectively. The mean induction time after darting was 5 seconds greater than the upper limit of the predefined time interval.


CONCLUSIONS
The higher dose requirement of MED-KET administration outdoors, compared with indoors, was explained by factors inherent in the darting technique and the different confinements. The iteration and the prediction methods seem applicable for determination of optimal doses of MED-KET in reindeer. The iteration and the prediction procedures may be used to reduce the number of experimental animals in dose-response studies in other species.
Ryeng
K A
KA
Norwegian School of Veterinary Science, Department of Arctic Veterinary Medicine, Tromsø.
Arnemo
J M
JM
Larsen
S
S
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D000829:Animals, Domestic; D004305:Dose-Response Relationship, Drug; D005260:Female; D007103:Immobilization; D007267:Injections; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D012016:Reference Values; D012053:Reindeer; D015203:Reproducibility of Results; D013997:Time Factors
D000700:Analgesics; D007649:Ketamine; D020926:Medetomidine