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.     

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 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.     

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.     

Yohimbine reversal of ketamine-xylazine immobilization of raccoons (Procyon lotor)

Six adult raccoons (Procyon lotor) were sedated with a combination of ketamine hydrochloride (KH) at 10 mg/kg body weight and xylazine hydrochloride (XH) at 2 mg/kg body weight intramuscularly (i.m.). Twenty min after the KH-XH combination was given, yohimbine hydrochloride (YH) at either 0.1 mg/kg (Trial 1) or 0.2 mg/kg (Trial 2) body weight or a saline control (Trial 3) was administered intravenously (i.v.). The time to arousal, time to sternal recumbency and time to walking were recorded. These times were significantly shortened after YH administration [e.g., mean time to walking (MTW) at 0.2 mg/kg YH = 23.7 min] as compared to the saline controls (MTW = 108.8 min). Heart and respiratory rates both increased after YH administration, while body temperature remained constant. A fourth trial was performed using a higher ratio of KH to XH (45:1 rather than 5:1) to mimic sedation as performed in the field. The mean time to arousal (MTA) and MTW in this trial (1.3 and 23.7 min, respectively) were significantly shorter than controls and similar to YH trials performed after immobilization with 5:1 KH-XH. Yohimbine hydrochloride may be useful in field studies that require sedation of raccoons using KH-XH combinations.     

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.     

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)     

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.     

Butorphanol/xylazine/ketamine immobilization of free-ranging Baird's tapirs in Costa Rica

Cardiopulmonary effects and the utility of a butorphanol/xylazine/ketamine combination were evaluated during twenty immobilizations of sixteen Baird's tapirs (Tapirus bairdii) between March 1996 and January of 1998 in Corcovado National Park (Costa Rica). The animals were attracted to a bait site and darted from tree platforms. The tapirs were estimated to weigh between 200 to 300 kg. Actual weights of three tapirs taken at later dates fell within the estimated range. A butorphanol, 48+/-1.84 (x +/- SE) mg/animal IM, and xylazine, 101+/-2.72 mg/animal IM, combination was used to immobilize the animals. In some instances, ketamine was used either IM or IV at 187+/-40.86 mg/animal to prolong the immobilization period in addition to the butorphanol/xylazine combination. Naltrexone was used IM to reverse butorphanol at 257+/-16.19 mg/animal. Either yohimbine, 34+/-0.61 or tolazoline at 12+/-10.27 mg/animal, was used to reverse xylazine. The mean time from dart impact to first visible effect was 4.63+/-0.50 min (x +/- SE). Mean time to sternal recumbency was 12.21+/-1.08 min. Mean time the tapirs were immobilized was 45.63+/-3.6 min. Mean time to return to sternal recumbency and standing in animals that received yohimbine and naltrexone was 3.16+/-1.06 and 5.33+/-1.45 min, respectively. Mean time to return to sternal recumbency and standing in animals that received tolazoline and naltrexone was 1.57+/-0.39 and 3.14+/-0.51 min, respectively. Cardiopulmonary parameters including heart rate, respiratory rate, body temperature, electrocardiogram, percent oxygen satoration, and indirect blood pressure were recorded. Arterial blood gas analysis was performed on four animals. A mild degree of hypoxemia was evidenced by low arterial oxygen saturations. Five of 14 (36%) animals measured had oxygen saturations below 90%. Bradycardia (heart rates <45 BPM) was an expected finding in 11 (55%) immobilizations. Induction, recovery and muscle relaxation of each immobilization was graded. Premature arousal, which occurred in six (30%) animals, was the only problem associated with the immobilizations. Butorphanol/xylazine is a recommended protocol for immobilization of calm, free-ranging tapirs lasting less than 30 min. Supplemental intravenous administration of ketamine is recommended for longer procedures. Nasal insufflation of oxygen is recommended.     

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.     

Field immobilization of Molina's hog-nosed skunk (Conepatus chinga) using ketamine and xylazine

We injected 27 adult Molina's hog-nosed skunks (Conepatus chinga) intramuscularly by hand with ketamine hydrochloride (KH) and xylazine hydrochloride (XH) in the Pampas grassland of Argentina. Skunks were immobilized with a mean (±SD) dosage of 24.9±6.5 mg/kg KH and 1.9±0.6 mg/kg XH. The mean effective dosages of KH (27.6 mg/kg) and XH (1.7 mg/kg) were higher and lower, respectively, than those reported in skunks previously. Mean induction and recovery time were 5.3±1.9 min and 47.7±18.5 min, respectively. Hypothermia was the only problem detected in field immobilization and occurred in winter but did not appear to be associated with to drug doses. We conclude that KH/XH is a safe immobilizing drug combination for Molina's hog-nosed skunk.     

Immobilization of free-ranging African lions (Panthera leo) with a combination of xylazine hydrochloride and ketamine hydrochloride

The combination of 55 mg/ml xylazine hydrochloride and 200 mg/ml ketamine hydrochloride was effective for immobilizing African lions in Tanzania. Nineteen adult females were given between 55 and 110 mg xylazine hydrochloride in the first dart. Initial doses of 110 mg xylazine hydrochloride and 450 mg ketamine hydrochloride equivalent to greater than 0.9 mg/kg xylazine hydrochloride were most effective in achieving rapid immobilization. Lower doses of xylazine hydrochloride required supplementation with ketamine hydrochloride. These doses could be delivered easily in 3-ml darts. The use of lightweight darts and a blowgun was found to be useful as a supplement to longer range dart projector systems since many animals could be approached at short range.     

A comparison of ketamine/xylazine and ketamine/xylazine/acepromazine anesthesia in the rabbit

Parenteral anesthetic combinations such as ketamine and xylazine have become the agents of choice for anesthesia in the rabbit, because they are effective, easily administered and inexpensive. A number of recent reports have recommended including acepromazine in this combination, but a critical evaluation of this combination in the rabbit has not been reported. Five adult New Zealand white rabbits were anesthetized intramuscularly with ketamine (35 mg/kg) and xylazine (5 mg/kg) with or without acepromazine (0.75 mg/kg). The study was conducted in a double blind fashion, where each rabbit was administered both combinations at a minimum of 7 day intervals. Physiologic parameters were evaluated including heart rate, respiratory rate, central arterial blood pressure, pedal, palpebral and postural reflex activity. The duration of general anesthesia, estimated by the time elapsed between the loss and return of the palpebral reflex, was greater (means = 99 +/- 20 minutes) when acepromazine was employed in the combination compared to (means = 77 +/- 5 minutes) when ketamine/xylazine were used alone. Mean central arterial blood pressure reached a lower level when acepromazine was utilized (means = 46 +/- 8 mm/Hg) than when it was not (means = 57 +/- 12 mm/Hg.). The addition of acepromazine in a ketamine/xylazine combination resulted in a 28% longer period of anesthesia, a 19% lower mean central arterial blood pressure and a 32% longer recovery of postural reflexes. The ketamine/xylazine/acepromazine combination is a useful regimen for normovolemic animals when anesthetic duration greater than that produced by ketamine/xylazine alone is required.     

The effects of xylazine hydrochloride on intrauterine pressure in the cow

The effect of xylazine on bovine intrauterine pressure was studied in the diestrous and estrous cow. Ten milligrams of xylazine and 50 units of oxytocin were administered intravenously to 11 diestrous and 8 estrous nonlactating Holstein cows after an intrauterine catheter was placed per vaginam. Xylazine produced intrauterine pressure responses which did not differ statistically from those seen with oxytocin. Intrauterine pressure increased and waves of contractions were observed within 1.5 min after administering xylazine and oxytocin to estrous and diestrous cows. The pharmacological basis for the oxytocic-like action of xylazine is presently unknown.     

Sufentanil and xylazine immobilization of Rocky Mountain elk

From October 2009 through July 2010, five captive, 3-yr-old, female Rocky Mountain elk (Cervus elaphus) and nine free-ranging elk (one male, eight female) were immobilized with 0.1 mg/kg sufentanil plus 0.5 mg/kg xylazine which was antagonized with 1 mg/kg naltrexone and 2 mg/kg tolazoline. Induction and recovery times averaged 4.9 ± 0.3 min and 3.9 ± 0.4 min, respectively. Physiologic and blood gas parameters as well as bispectral index (BIS) were measured on the captive elk every 10 min for 30 min. Immobilization induced profound hypoxemia via hypoventilation and ventilation-perfusion mismatching as demonstrated by depressed partial pressure of arterial oxygen (P(a)O(2)) and increased partial pressure of arterial carbon dioxide (P(a)CO(2)). The only values to significantly (P<0.05) change over time were base excess (BE), bicarbonate (HCO(3)), and lactate. Bispectral index is a measure of anesthetic depth. The average BIS value over the 30 min period (59.1 ± 2.4) was higher than the BIS value at the approximate point where elk lose consciousness, which indicated that this drug combination produced neuroleptanalgesia but not general anesthesia. Sufentanil and xylazine provided effective remote immobilization in elk and could be substituted for carfentanil or thiafentanil and xylazine should the need arise.     

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.     

Hematological and serum biochemical values in cynomolgus monkeys anesthetized with ketamine hydrochloride

The effects of ketamine anesthesia on both hematological and serum biochemical variables were investigated in 19 male and 15 female cynomolgus monkeys. Blood samples were obtained from the cephalic vein within 30 minutes of an intramuscular injection of ketamine hydrochloride (10 mg/kg). Ketamine anesthesia caused a reduction in leukocyte counts and a significant reduction in lymphocytes percentages. Ketamine anesthesia also increased the serum activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatine phosphokinase (CPK), but reduced the serum concentrations of glucose, inorganic phosphate, sodium and potassium. The alterations of hematological and serum biochemical values will be discussed. These alterations should be considered when designing studies for and interpreting data from cynomolgus monkeys.     

A comparison of carfentanil/xylazine and Telazol/xylazine for immobilization of white-tailed deer

October 2001 to January 2002, captive free-ranging white-tailed deer (Odocoileus virginianus) were immobilized with a combination of carfentanil citrate and xylazine hydrochloride. From this study, we selected a dose of carfentanil/xylazine for the purpose of comparing immobilization parameters and physiologic effects with those of a combination of tiletamine and zolazepam (Telazol) and xylazine. Animals were initially given intramuscular injections of 10 mg xylazine and one of four doses of carfentanil (i.e., 0.5, 1.0, 1.5, and 2.0 mg). A carfentanil dose of 1.2 mg (x +/- SD = 23.5 +/- 3.2 microg/kg) and 10 mg xylazine (0.2 +/- 0.03 mg/kg) were selected, based on induction times and previously published reports, to compare with a combination of 230 mg of Telazol (4.5 +/- 0.6 mg/kg) and 120 mg xylazine (2.3 +/- 0.3 mg/kg). Time to first observable drug effects and to induction were significantly longer for deer treated with carfentanil/xylazine than with Telazol/xylazine (P < 0.01). Hyperthermia was common in deer immobilized with carfentanil/xylazine, but heart rate, respiration rate, and hemoglobin saturation were within acceptable levels. Degree of anesthesia of deer immobilized with Telazol/xylazine was superior to deer immobilized with carfentanil/xylazine. The combination of 120 mg of naltrexone hydrochloride and 6.5 mg of yohimbine hydrochloride provided rapid and complete reversal (1.9 +/- 1.1 min) of carfentanil/xylazine immobilization. Animals immobilized with Telazol/xylazine had long recovery times with occasional resedation after antagonism with 6.5 mg of yohimbine. The combination of carfentanil and xylazine at the doses tested did not provide reliable induction or immobilization of white-tailel (leer even though drug reversal was rapid and safe using naltrexone and yohimbine.