Abstract:

[Objective] The present study aimed to assess the anesthetic effect of xylazine hydrochloride in rabbits. [Method] Twelve New Zealand rabbits were assigned into the following four groups at random with 3 rabbits in each group: an ear intravenous injection （IV） with fixation group, a buttocks intramuscular injection （IM） with fixation group, an ear IV without fixation group, and a buttocks IM without fixation group. The rabbits in different groups were given xylazine hydrochloride at a dosage of 3 mg/（kg·BW） by corresponding administration approaches. After administration, the rabbits in the fixation groups were in supine position with head and limbs fixed, and those in the non-fixation groups were in natural prone position. Thirty min post the first administration, the rabbits were given xylazine hydrochloride again at a dosage of 2 mg/（kg·BW） by the same approach as the first administration. Basic vital signs and anesthetic reaction indexes of the rabbits were monitored 10 min prior to administration as well as 5, 30 and 60 min post the second administration. [Result] The respiratory and pulse frequencies of the four groups after administration of xylazine hydrochloride decreased significantly or extremely significantly （P<0.05 or P<0.01） compared with those before administration. At 60 min after administration, the pulse frequency of IM fixation group was the lowest, which was significantly （P<0.05） lower than that of IV non-fixation group. The rectal temperature of the four groups at 30 min after administration was significantly （P<0.05） lower than that before administration. Except for the IV non-fixation group, the rectal temperature of each group at 60 min after administration was extremely significantly （P<0.01） lower than that before administration. At 60 min after administration, the rectal temperature of IM fixation group was the lowest, which was extremely significantly （P<0.01） lower than that of IV non-fixation group. In IM fixation group, no righting reflex, eyelash reflex and pain reflex were observed at different time points after administration. In IV non-fixation group, the righting reflex, eyelash reflex and pain reflex were observed in all 3 rabbits at 60 min after administration.The anesthetic period of IM fixation group was the longest, which was significantly （P<0.05）longer than that of IV fixation group and was extremely significantly （P<0.01） longer than that of IV non-fixation group and IM non-fixation group. [Conclusion] Xylazine hydrochloride should be administered by the route of IM in anesthesia of rabbits. A first administration at the dosage of 3 mg/（kg·BW） is recommended, and a subsequent administration at the dosage of 2 mg/（kg·BW） should be given 30 min later. The rabbits should be fixed immediately after administration.

Key words: xylazine hydrochloride, rabbit, fixation, anesthetic period