Efficacy of immobilizing free-ranging elk with Telazol and xylazine hydrochloride using transmitter-equipped darts

From January 1999 to April 2002, 14 free-ranging elk were darted with a mixture of Telazol reconstituted with xylazine hydrochloride (HCl) in a forested habitat in southwestern Oklahoma and north-central Arkansas. Elk were darted from ground blinds, tree stands, or a vehicle at distances of 14-46 m and were recovered 37-274 m from the dart site. Elk were located using radiotelemetry with 3-cc disposable Pneu-dart transmitter darts. Mean+/-SD dose of Telazol and xylazine HCl was 590+/-192 mg/ml and 276+/-153 mg/ml, respectively, and mean time to standing after injection of reversal agent was 27 min (range: 1-65 min). The combination of Telazol and xylazine HCl successfully immobilized free-ranging elk, and transmitter-equipped darts permitted successful location of sedated elk by two people in areas of dense forest cover. The dose required to sedate elk appeared to vary depending on physiology and behavior, but no drug-induced mortality occurred despite the wide variance in the doses administered. We recommend 500 mg Telazol reconstituted with 300 mg xylazine HCl as an initial dose for a >or=200 kg elk. If needed to achieve full sedation, up to 3 additional ml of the mixture may be administered without adverse effects.     

Effect of caffeine sodium benzoate, ketamine hydrochloride, and yohimbine hydrochloride on xylazine hydrochloride-induced anorexia in white-tailed deer

Fifteen male white-tailed deer (Odocoileus virginianus) were administered xylazine hydrochloride (1 mg/kg BW i.m.), xylazine hydrochloride (1 mg/kg i.m.) followed by caffeine sodium benzoate (10 mg/kg i.m.), xylazine hydrochloride (0.5 mg/kg i.m.) and ketamine hydrochloride (4.5 mg/kg i.m.), and xylazine hydrochloride (1 mg/kg i.m.) followed by yohimbine hydrochloride (0.125 mg/kg i.m.), in a Latin Square design. Mean dry matter intake (DMI) for 4 days pre-treatment was compared to each of 4 days post-treatment. A significant (P less than 0.01) decrease in DMI was found only on the first day following treatment for each of the four drug combinations. The percent decreases in DMI on the first 24-hr period after immobilization were: xylazine hydrochloride 47%, xylazine hydrochloride/caffeine sodium benzoate 36%, xylazine hydrochloride/yohimbine hydrochloride 36%, and xylazine hydrochloride/ketamine hydrochloride 31%. The xylazine hydrochloride/ketamine hydrochloride combination was found to be insufficient to adequately sedate the deer. The use of caffeine or yohimbine hydrochloride is recommended to reduce recumbency time, but offers no improvement in xylazine hydrochloride-induced anorexia.     

Xylazine hydrochloride-ketamine hydrochloride immobilization of free-living red foxes (Vulpes vulpes) in Spain.

A combination of xylazine hydrochloride-ketamine hydrochloride was used to immobilize 83 wild red foxes (Vulpes vulpes) (15 pups and 68 adults) at Do?ana National Park (Spain). Mean ketamine hydrochloride doses were 17.1 mg/kg (SE = 1.53) and 12.3 mg/kg (SE = 0.4) for pups and adults, respectively, and mean xylazine hydrochloride doses for the same groups were 6.2 mg/kg (SE = 0.63) and 4.7 mg/kg (SE = 0.14), respectively. Mean induction times and first reaction times were 1.6 minutes and 22.5 minutes for pups and 3.8 minutes and 39.4 minutes for adults, respectively. Recommended doses for wild adult foxes of unknown weight are 75 mg of ketamine hydrochloride and 20 mg of xylazine hydrochloride.     

Immobilization with a single dose of ketamine hydrochloride and a combination of xylazine hydrochloride-ketamine hydrochloride and antagonism by yohimbine hydrochloride in the Japanese monkey (Macaca fuscata)

Forty-nine free-ranging Japanese monkeys (Macaca fuscata) were immobilized with 4.3–15.6 mg/kg (mean±S.D.=10.0±2.5 mg/kg) of ketamine hydrochloride (HCl), and 27 Japanese monkeys kept in enclosures were immobilized with a combination of 0.8–1.4 mg/kg (1.0±0.2 mg/kg) of xylazine HCl and 4.0–7.1 mg/kg (5.0±0.6 mg/kg) of ketamine HCl. In the xylazine HCl-ketamine HCl combination, good myorelaxation was induced. The mean induction times for the single dosage of ketamine HCl and the xylazine HCl-ketamine HCl combination were 2.8±1.5 min and 6.9±4.4 min, respectively. The mean immobilization times with the single dosage of ketamine HCl and the xylazine HCl-ketamine HCl combination were 39.3±16.5 min and 58.8±34.2 min, respectively. A half dose of ketamine HCl in combination with xylazine HCl could also immobilize Japanese monkeys successfully. Administrations of 0.5 mg/kg i.v. and 1.0 mg/kg i.m. of yohimbine HCl as an antagonist to xylazine HCl at 30 min after the induction reduced the immobilization time to 31.4±0.5 min and 49.0±22.1 min, respectively. Yohimbine HCl appears to be an effective antagonist to combination anesthesia by xylazine HCl-ketamine HCl in the Japanese monkey.     

Antagonism of xylazine hydrochloride-ketamine hydrochloride immobilization in guineafowl (Numida meleagris) by yohimbine hydrochloride

The mean time to arousal (MTA), the mean time to sternal recumbency (MTSR) and the mean time to walking (MTW) were measured in 10 adult guineafowl (Numida meleagris) immobilized with a combination of xylazine hydrochloride (1 mg/kg) and ketamine hydrochloride (25 mg/kg). Yohimbine hydrochloride, given intravenously (1 mg/kg) at 40 min after the injection of the xylazine-ketamine, significantly shortened the MTA, the MTSR and the MTW compared to saline controls. Increasing the dosage of yohimbine to 2.5 mg/kg did not shorten recovery when compared to the lower dosage. No adverse effects were noted at either dosage of yohimbine. Yohimbine appeared to be a safe and effective antagonist of xylazine-ketamine immobilization in guineafowl and may prove useful in other avian species to produce more rapid recovery from xylazine-ketamine immobilization, xylazine sedation or xylazine overdosage.     

Yohimbine hydrochloride reversal of ketamine hydrochloride and xylazine hydrochloride immobilization of Bengal tigers and effects on hematology and serum chemistries

Six bengal tigers (Panthera tigris tigris) were immobilized five times at 2-wk intervals with ketamine hydrochloride (ketamine) and xylazine hydrochloride (xylazine) mixtures at different dose levels. Hematology and serum chemistry analyses on blood samples collected at each immobilization remained normal during the study. There were acute changes in hematocrit, chloride, potassium, glucose, and bilirubin as a function of xylazine dose level. The effect of yohimbine hydrochloride (yohimbine) on the depth and duration of immobilization was evaluated in a crossover design with every animal serving as its own control at each dose. Administration of yohimbine resulted in recovery of the animals within 4-8 min in contrast to greater than 60 min with no yohimbine treatment. There were no adverse effects noted with the yohimbine treatment and the tigers did not exhibit a relapse over the next 24 hr. Yohimbine at a dose of 5-15 mg per adult tiger provided effective reversal of 50-150 mg of xylazine per tiger.     

Use of yohimbine hydrochloride to reverse immobilization of polar bears by ketamine hydrochloride and xylazine hydrochloride

Yohimbine hydrochloride (YH) effectively reversed the immobilizing effects of ketamine hydrochloride (KH) combined with xylazine hydrochloride (XH) in 48 wild polar bears (Ursus maritimus) handled in the summer. Single intravenous doses of YH ranging between 0.029 and 0.198 mg/kg resulted in a median time of 10 min (range: 1-123 min) to post-injection recovery from KH-XH immobilization. Convulsions and muscle twitching were observed in some bears after YH was administered and one death occurred. Median respiratory rate and heartbeat rate increased from 5 br/min to 12 br/min and 51 BPM to 79 BPM, respectively, soon after yohimbine was administered. The median time to recovery after KH-XH administration, including processing and handling time, was 113 min for bears administered yohimbine and 202 min for bears not administered YH. After YH-induced recovery, polar bears showed signs of reduced awareness and many remained recumbent for undetermined periods although they could coordinate movements, stand, and walk or run if disturbed. YH proved to be a useful antagonist to immobilization induced by KH-XH in a field situation.     

Immobilization of swift foxes with ketamine hydrochloride-xylazine hydrochloride

There is an increasing need to develop field immobilization techniques that allow researchers to handle safely swift foxes (Vulpes velox) with minimal risk of stress or injury. We immobilized captive swift foxes to determine the safety and effectiveness of ketamine hydrochloride and xylazine hydrochloride at different dosages. We attempted to determine appropriate dosages to immobilize swift foxes for an adequate field-handling period based on three anesthesia intervals (induction period, immobilization period, and recovery period) and physiologic responses (rectal temperature, respiration rate, and heart rate). Between October 1998-July 1999, we conducted four trials, evaluating three different dosage ratios of ketamine and xylazine (2.27:1.2, 5.68:1.2, and 11.4:1.2 mg/kg ketamine:mg/kg xylazine, respectively), followed by a fourth trial with a higher dosage at the median ratio (11.4 mg/kg ketamine: 2.4 mg/kg xylazine). We found little difference in induction and recovery periods among trials 1-3, but immobilization time increased with increasing dosage (P < 0.08). Both the immobilization period and recovery period increased in trial 4 compared with trials 1-3 (P < or = 0.03). There was a high variation in responses of individual foxes across trials, making it difficult to identify an appropriate dosage for field handling. Heart rate and respiration rates were depressed but all physiologic measures remained within normal parameters established for domestic canids. We recommend a dosage ratio of 10 mg/kg ketamine to 1 mg/kg xylazine to immobilize swift foxes for field handling.     

Rapid reversible immobilization of feral stallions using etorphine hydrochloride, xylazine hydrochloride and atropine sulfate

Forty-eight newly captured free-ranging feral stallions (Equus caballus) from two different locations and six captive stallions were immobilized using combinations of etorphine hydrochloride, xylazine hydrochloride and atropine sulfate with or without acepromazine. Six animals were immobilized twice, 1 mo apart. The drugs were administered either intramuscularly (n = 13) or intravenously (n = 44). Mean immobilization time (+/- SE) after intravenous (i.v.) injection of etorphine, xylazine and atropine was 55 +/- 4 sec (range 20 to 185 sec) compared to 708 +/- 131 sec (range 390 to 1,140 sec) for intramuscular (i.m.) injection. Immobilization was reversed with i.v. administration of 3 to 11 mg diprenorphine hydrochloride and 16 to 24 mg yohimbine hydrochloride. Average time from administration to standing and walking was 86 +/- 7 sec (n = 55). Reversal of etorphine-induced immobilization with an amount of diprenorphine equal to the etorphine and administered i.v. was as effective as a 2:1 ratio of diprenorphine to etorphine. Acepromazine had no effect on induction time, but decreased relaxation after immobilization and prolonged ataxia after reversal of the etorphine and xylazine. Eight free-ranging horses were immobilized in 708 +/- 132 sec by darting with 5.5 mg etorphine, 1,300 mg xylazine and 15 mg atropine from a helicopter. Three animals died during the study: one immediately after reversal of an i.v. administration, one from a broken neck during induction from darting, and one was found a week later at the site of darting.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immobilization of white-tailed deer with xylazine hydrochloride and ketamine hydrochloride and antagonism by tolazoline hydrochloride

Fourteen penned and 17 free-ranging white-tailed deer (Odocoileus virginianus Rafinesque) were singularly or repeatedly immobilized with 100 mg xylazine hydrochloride (HCl) and 300 mg ketamine HCl. The mean times from intravenous injection to ambulation for 1.0, 2.0, and 4.0 mg/kg body weight doses of tolazoline HCl were 13.5, 10.5, and 9.2 min. Deer not receiving tolazoline HCl recovered in an average of 168 min. Heart rates significantly (P less than 0.001) increased from 47 to 83 beats/min after tolazoline HCl administration, representing a return to normal rate. Tolazoline HCl had no effect on respiratory rate. A total of 85 reversals with tolazoline HCl resulted in no apparent adverse reactions.     

Prolonged and multiple immobilizations of the southern elephant seal using ketamine hydrochloride-xylazine hydrochloride or ketamine hydrochloride-diazepam combinations

Thirty seven southern elephant seals (Mirounga leonina) were singularly or repeatedly immobilized with combinations of ketamine hydrochloride (HCl) and xylazine HCl or ketamine HCl and diazepam. Atropine sulphate was included in the drug combinations. To permit experimental procedures the seals were immobilized for periods of 30-330 min. The mean induction dose of ketamine HCl was 8.71 +/- 0.25 mg/kg (mean +/- SE). The mean induction time was 16.02 +/- 2.62 min. For the elephant seals immobilized for periods in excess of 180 min, the mean dose of ketamine HCl used per hr was 3.31 +/- 0.13 mg/kg/hr and the mean dose of ketamine HCl used per hr postinduction was 1.31 +/- 0.15 mg/kg/hr. The mean dose of diazepam used was 0.09 +/- 0.01 mg/kg and the mean dose of xylazine HCl was 0.41 +/- 0.01 mg/kg. Elephant seals were weighed on 20 occasions (weight range: 897-1,932 kg) and the relationship between standard length and weight was found to be: Weight = 9.98 length - 2,317.63 (r2 = 0.724). Adverse reactions to seals immobilized only once or twice were not observed. Two seals immobilized on three occasions developed abscesses at the site of injection.     

Immobilizing wild mountain lions (Felis concolor) with ketamine hydrochloride and xylazine hydrochloride

A mixture of 120 mg ketamine hydrochloride (KHCL)/20 mg xylazine hydrochloride (XHCL)/ml was used to immobilize 37 wild mountain lions (Felis concolor) 46 times. Observations were recorded during 37 trials that included kittens, adult females, and adult males. Dosages were based on 11 mg KHCL and 1.8 mg XHCL/kg estimated body weight. Actual doses for 24 lions requiring a single injection for immobilization ranged from 4.7-15.8 mg KHCL/kg and 0.8-2.6 mg XHCL/kg. Induction, duration, and recovery times did not differ (P greater than 0.05) between the sex and age classes. Two kittens were overdosed with the drug combination, but the effects were not life threatening. Eleven other lions, nine of which were initially underdosed, required additional injections of the drug combination for safe handling. Immobilization was characterized initially by semi-consciousness, open eyelids, pupillary dilation, and muscle rigidity. Later, most lions appeared unconscious, muscles relaxed, and breathing slowed considerably. No convulsions or hypersalivation occurred. The KHCL/XHCL mixture given at approximately 11 mg KHCL and 1.8 mg XHCL/kg body weight proved useful for immobilizing wild mountain lions for research purposes. Suggestions for case of immobilized cats are included.     

Immobilization of fishers (Martes pennanti) with ketamine hydrochloride and xylazine hydrochloride

A combination of 100 mg ketamine hydrochloride (KH) and 20 mg xylazine hydrochloride (XH) was used to immobilize fishers (Martes pennanti). Four adult males were intramuscularly injected a total of five times at dosages between 22.4 to 29.0 mg/kg KH and 4.1 to 6.6 mg/kg XH. Mean (+/- SE) induction time and arousal time were 3.3 +/- 0.5 min and 76.8 +/- 12.1 min, respectively. Respiration, heart rate, and body temperature in response to sedation appeared normal. A 5:1 mixture of KH-XH appears to be a safe immobilizing agent for fishers.     

Xylazine hydrochloride-ketamine hydrochloride immobilization of wolves and its antagonism by tolazoline hydrochloride

Fourteen wolves (Canis lupus L.) were singularly or repeatedly immobilized with 30 mg xylazine hydrochloride (HCl) and 400 mg ketamine HCl. Mean induction time was 5.3 +/- 4.6 min (mean +/- SD). Administration of 8.0 mg/kg tolazoline HCl as an antagonist significantly reduced immobilization times from 148.0 +/- 52.7 to 47.9 +/- 8.9 min (F = 63.69, df = 1,17, P less than 0.05). The average times from injection to ambulation for 2.0, 4.0, and 8.0 mg/kg tolazoline HCl were 35.2 +/- 31.8, 18.5 +/- 11.7, and 10.2 +/- 9.1 min. Tolazoline HCl increased heart rates significantly (P less than 0.001) from 75 +/- 14 to 120 +/- 23 beats/min, reversing a xylazine HCl-induced bradycardia. Respiratory rates also increased significantly (P less than 0.01) after tolazoline HCl injection from 19 +/- 7 to 28 +/- 8 breaths/min. Immobilization resulted in an initial hypertension which was normalized after tolazoline HCl administration. One female wolf had a single sinoatrial block within 1 min of receiving tolazoline HCl. Tolazoline HCl appears to be an effective antagonist for xylazine HCl-ketamine HCl immobilization of wolves.     

Evaluation of xylazine hydrochloride as the sole immobilizing agent in moose and caribou--and its subsequent reversal with idazoxan

Xylazine hydrochloride was used as the sole immobilizing agent in moose and caribou. The animals were free-ranging and immobilization was accomplished from a helicopter using powered darts. Following a period of immobilization during which radiotelemetry collars were fitted, the animals were revived using idazoxan (RX 781094) or its methoxy analogue RX 821002. Xylazine was administered at dose rates of approximately 3.0 mg/kg and 5.0 mg/kg to the moose and caribou, respectively. Moose received 430 +/- 27 mg of xylazine and a mean dose of 10 mg idazoxan (RX 781094). Caribou received 485 +/- 30 mg xylazine and a mean dose of 4 mg idazoxan (RX 821002). This technique gave adequate immobilization with rapid recovery of consciousness in both species.     

Antagonism of xylazine hydrochloride sedation in raptors by yohimbine hydrochloride

The mean time to initial reversal response (MTIRR) and the mean time to perching (MTP) were measured in 34 raptors sedated with xylazine hydrochloride with dosages ranging from 1.0 to 20 mg/kg intravenously (i.v.) and 2.5 to 20.0 mg/kg intramuscularly (i.m.). Yohimbine hydrochloride, given i.v. (0.2 mg/kg), 30 min after the injection of the xylazine, shortened the MTIRR and MTP compared to the controls. No adverse effects were noted due to the use of yohimbine. Yohimbine appeared to be a safe and effective antagonist for xylazine sedation in raptors.     

Tolazoline antagonises ketamine–xylazine anaesthesia in an endangered Black buck (<Emphasis Type="Italic">Antilope cervicapra</Emphasis>)

Seventy-seven anaesthetic events were carried out in 22 captive adult Black bucks (Antilope cervicapra) of either sex with a combination of 2 mg kg⁻¹ ketamine hydrochloride with 0.25 mg kg⁻¹ xylazine hydrochloride using a dart delivered from a blowpipe. Randomised anaesthetised animals received an intravenous injection of either yohimbine hydrochloride (0.125 or 0.25 mg kg⁻¹) or tolazoline hydrochloride (1 or 2 mg kg⁻¹) after 30–40 min of anaesthesia to antagonise the anaesthetic effects. Ketamine–xylazine induced smooth, rapid and reliable anaesthesia within 5–7 min of darting with no clinical adverse effects and causalities during or post-anaesthesia. Yohimbine failed to antagonise the anaesthetic effects of ketamine–xylazine in the Black buck. On the other hand, tolazoline was found to be very effective in hastening recovery in dose-dependent manner within 0.5–1.5 min. This study documents the first report of ketamine–xylazine anaesthesia and its antagonism by tolazoline in captive Black buck.     

Xylazine hydrochloride for immobilizing captive white-tailed deer (Odocoileus virginianus)

White-tailed deer (Odocoileus virginianus) were immobilized with intramuscular doses of xylazine hydrochloride to facilitate blood sampling. Injection was either remotely by modified dart syringe or manually by hand syringe. In 86 attempts to immobilize female deer (aged 2, 5–6 yr) 73.3% were effectively immobilized for 90 min while 108 attempts to immobilize male deer (aged 2–3 yr) for at least 30 min resulted in 94.4% effective immobilization. Induction times averaged approximately 10 min for both sexes. Treated deer exhibited sedation, hypothermia, reduced respiration rates, anorexia, salivation, tongue paralysis and diarrhea. Deer also showed a loss or partial loss of pedal, palpebral, corneal, and swallowing reflexes during immobilization. Side effects of xylazine and length of immobilization appeared to be dose dependent. Mortality as a result of xylazine immobilization was four male deer out of a total of 194 immobilizing attempts on both sexes. Recommendations are given concerning care of deer during immobilization and recovery.     

Chemical immobilization of free-ranging North American bison (Bison bison) in Badlands National Park, South Dakota

Twenty-six free-ranging North American bison (Bison bison) (22 adult bulls, one yearling male and three adult females) were immobilized using a combination of carfentanil and xylazine. For carfentanil the dose range (mean +/- SD) was 1.8-5.0 micrograms/kg (2.4 +/- 0.7 micrograms/kg) and for xylazine 0.004-0.125 mg/kg (0.07 +/- 0.03 mg/kg). Induction time (mean +/- SE) was 14.2 +/- 2.9 min (median 8 min), while the total mean reversal time after administration of a narcotic antagonist was 9.0 +/- 1.4 min (median 8 min). Only one animal that received the highest initial dose of carfentanil (2.5 mg) showed evidence of becoming "re-narcotized." Five animals required two or more doses of carfentanil before becoming immobilized. Overall, small volumes of drug used (mean = 0.62 ml for carfentanil, 0.53 ml for xylazine) enabled the use of 1 to 2 ml darts, increasing both accuracy and impact safety. Darting success approached 100%.     

Yohimbine hydrochloride as an antagonist to xylazine hydrochloride-ketamine hydrochloride immobilization of white-tailed deer

Thirteen captive and one free-ranging white-tailed deer (Odocoileus virginianus) were immobilized one to six times each with ketamine hydrochloride and xylazine hydrochloride during winter and spring in northern Minnesota. Administration of 0.09 to 0.53 mg of yohimbine hydrochloride per kg IV after each trial reversed the immobilization. The deer raised their heads within a median time of 2.0 min, stood in 6.0 min and walked away in 9.5 min. No adverse side effects were observed for several weeks following the immobilization.