Yohimbine injection in deer

Abstract

Extract

Sir:— In the 12 months since the completion of the trials reported in this Journal(1) over 3000 doses of yohimbine have been used to reverse xylazine sedation in deer at Invermay and in field trials throughout New Zealand. During this time four deer have suffered transient convulsions characterised by tetanic spasms, paddling of the limbs, inability to stand and rapid nodding of the head. This was accompanied by rapid blinking of the eyelids and grinding of the teeth. These signs abated in 5 to 10 minutes after which time the deer relaxed and regained its ftet in 10 to 20 minutes. In the 30 minutes prior to yohimbine administration these deer had received a single injection of xylazine (0.5 to 1.0 mg/kg) and on one occasion the xylazine was given in conjunction with Img of fentanyl and 8 mg azaperone (0.1 ml Fentaz). On each occasion the intention was to inject yohimbine at the recommended dose rate (1) (0.2 to 0.25 mg/kg) into the jugular vein and the convulsions commenced within five seconds of this injection. Normally it takes one to three minutes for reversal ofxylazine sedation to occur. Thus it is highly likely that these injections were intra- carotid, thereby resulting in a very high concentration of yohimbine in the cranial arteries. All four animals recovered and there were no apparent after effects. These convulsions occured more rapidly hut were less severe than those expcrienced with the combination of yohimbine and 4-aminopyridine reported in the earlier trail.(1)