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.     

Effectiveness of antagonists for tiletamine-zolazepam/xylazine immobilization in female white-tailed deer

A combination of tiletamine-zolazepam/xylazine (TZ/X) is effective in the chemical immobilization of white-tailed deer (Odocoileus virginianus); however, the lengthy duration of immobilization may limit its usefulness. From October to November 2002, 21 captive female deer were assigned randomly to an alpha(2) antagonist treatment to reverse xylazine-induced sedation (seven does per group). All deer were given 220 mg of TZ (4.5+/-0.4 mg/kg) and 110 mg of X (2.2+/-0.2 mg/kg) intramuscularly (IM). Antagonist treatments were either 200 mg of tolazoline (4.0+/-0.4 mg/kg), 11 mg of atipamezole (0.23+/-0.02 mg/kg), or 15 mg of yohimbine (0.30+/-0.02 mg/kg) injected, half intravenously and half subcutaneously, 45 min after the IM TZ/X injection. In addition, 10 other deer (five per group) were immobilized as before and then given tolazoline (200 mg) after 45 min, with either a carrier (dimethyl sulfoxide [DMSO]) or carrier (DMSO) plus flumazenil (5 mg) to reverse the zolazepam portion of TZ. Mean times from antagonist injection until a deer raised its head were different for alpha(2) antagonist treatments (P=0.02). Times were longer for yohimbine (62.3+/-42.7 min) than for either atipamezole (24.3+/-17.1 min) or tolazoline (21.3+/-14.3 min). Mean times from antagonist injection until standing were not different (P=0.15) among yohimbine (112.0+/-56.4 min), atipamezole (89.7+/-62.8 min), or tolazoline (52.6+/-37.2 min). A sedation score based on behavioral criteria was assigned to each deer every 30 min for 5 hr. On the basis of sedation scores, tolazoline resulted in a faster and more complete reversal of immobilization. Flumazenil treatment did not affect recovery.     

Reversal by tolazoline hydrochloride of xylazine hydrochloride-ketamine hydrochloride immobilizations in free-ranging desert mule deer

We captured 10 free-ranging desert mule deer (Odocoileus hemionus crooki) (five males and five females) by net-gun from a helicopter and immobilized them with xylazine hydrochloride (HCl) (100 mg) and ketamine HCl (300 to 400 mg) injected intramuscularly. Arousal and ambulation times were 13.9 +/- 4.2 and 14.3 +/- 4.2 min in eight deer injected intravenously with tolazoline HCl (3.0 mg/kg). We observed a curvilinear relationship (R = 0.50, P less than 0.01) between rectal temperature and time after induction of anesthesia. Mean peak temperature (41.4 C) occurred at 23.7 +/- 3.2 min postinduction and was greater (P less than 0.01) than the mean temperature measured initially (40.8 C). Heart and respiratory rates (108 beats/min and 75 breaths/min) were elevated prior to immobilization. Mean heart rate increased (P less than 0.05) from 90 +/- 9 beats/min in anesthetized deer to 120 +/- 13 beats/min after tolazoline HCl injection. A 20% capture-related mortality rate suggests this combination of physical and chemical capture has serious limitations. Captive deer permitted to recover from xylazine HCl-ketamine HCl immobilization without a reversal agent were able to walk in 290 +/- 79 min.     

Capture and immobilization of wild brown palm civets in Western Ghats

A mixture of 15 mg/kg body weight ketamine hydrochloride (KE) and 1.5 mg/kg body weight xylazine hydrochloride (XY) was used to successfully immobilize free-ranging brown palm civets (Paradoxurus jerdoni). Between March 1998 and June 1999, 10 immobilizations of 7 individuals were carried out in tropical rainforests of the Kalakad-Mundanthurai Tiger Reserve (India). Five males and two females were captured in Havahart live traps, using banana as bait. The mean dosage for the animals, whose weight (mean +/- SD) was 2.4 kg +/- 0.8 was 36.0 +/- 11.0 mg KE and 3.7 +/- 1.1 mg XY, administered intramuscularly. Mean time for lateral recumbency was 6.1 +/- 3.78 min (n = 10) and the mean time taken for complete recovery was 84.9 +/- 28.8 min (n = 9). Recovery was gradual and no fatalities or injuries occurred during the operation. The drug combination used was effective and has the potential for immobilizing other viverrids.     

Ketamine/xylazine/butorphanol: a new anesthetic combination for rabbits.

Ketamine is often used in combination with tranquilizers to produce surgical anesthesia in rabbits. While generally effective, there is considerable variation in the depth and duration of anesthesia achieved with ketamine combinations. Butorphanol is a mixed agonist-antagonist opioid that is widely used in a variety of other species. In this study, the commonly used ketamine (35 mg/kg)/xylazine (5 mg/kg) combination is compared with ketamine (35 mg/kg)/xylazine (5 mg/kg)/butorphanol (0.1 mg/kg). Rabbits were anesthetized on consecutive weeks with one of the two regimens. Physiologic parameters including heart rate, respiratory rate, blood pressure and arterial blood gases (pH, PO2, PCO2) were measured throughout anesthesia. Loss of palpebral, pedal and righting reflexes were recorded and reflexes were subsequently evaluated. The addition of butorphanol prolonged reflex loss to 140% (X = 68 min +/- 20 SEM) of control for palpebral reflex; 506% (X = 52 min +/- 18 SEM) of control for pedal reflex; and 159% (X = 128 min +/- 21 SEM) of control for righting reflex. Addition of butorphanol to ketamine/xylazine resulted in mild alterations in the physiologic changes traditionally associated with this combination. Butorphanol can be safely added to the ketamine/xylazine combination in rabbits and results in moderate increases in the duration of reflex loss.     

Effects of yohimbine on bradycardia and duration of recumbency in ketamine/xylazine anesthetized ferrets

Eleven adult ferrets (Mustela putorius furo) were anesthetized with ketamine hydrochloride (25 mg/kg, IM) and xylazine hydrochloride (2 mg/kg, IM). Fifteen minutes post-ketamine/xylazine injection, ferrets were treated with yohimbine hydrochloride at a dose of 0.5 mg/kg, or an equal volume of physiologic saline, intramuscularly. Each ferret served as its own control by randomly receiving both treatments with a minimum interval of 2 weeks between treatments on any one ferret. At 15 minutes post-ketamine/xylazine injection, mean heart rate measurements for both treatment groups were 27% less than the mean heart rate measurement reported for unanesthetized ferrets. Intramuscular administration of yohimbine antagonized the ketamine/xylazine induced bradycardia in 10 of the 11 ferrets, (p = 0.0001). In yohimbine treated ferrets, an increase in mean heart rate measurement was noted 5 minutes after the intramuscular administration of yohimbine, and followed, over the next 15 minutes, by a progressive increase in mean heart rate. However, a corresponding decrease in mean heart rate measurement was observed in saline treated controls. Fifteen minutes after the injection of yohimbine, the mean heart rate measurement of yohimbine treated animals had increased to 194 beats per minute. This mean heart rate measurement is nearly 30% greater than the mean heart rate of 150 beats per minute measured at 15 minutes post-saline injection in saline treated controls. Also, yohimbine treatment significantly reduced duration of recumbency in 10 of 11 ferrets (p = 0.0001). Mean duration of recumbency for yohimbine treated ferrets was 41 +/- 9.7 minutes, whereas mean duration of recumbency for saline treated ferrets was determined to be 80 +/- 11.4 minutes.(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.     

Immobilization of California sea lions using medetomidine plus ketamine with and without isoflurane and reversal with atipamezole

The use of medetomidine and ketamine, alone and in combination with isoflurane, with atipamezole reversal was evaluated for immobilizing 51 California sea lions (Zalophus californianus) for a variety of medical procedures at a rehabilitation center in northern California (USA) between May 1997 and August 1998. Animals were given 140 microg/kg medetomidine with 2.5 mg/kg ketamine intramuscularly. Mean (+/-SD) time to maximal effect was 8+/-5 min. At the end of the procedure, animals were given 200 microg/kg atipamezole intramuscularly. Immobilization and recovery times were, respectively, 25+/-12 and 9+/-7 min for 35 animals maintained with medetomidine and ketamine alone and 58+/-30 and 9+/-9 min for 16 animals intubated and maintained with isoflurane. No mortalities occurred as a result of the immobilizations. Disadvantages of the medetomidine and ketamine combination included a moderate variation in time to maximal effect and plane of sedation, a large injection volume and high cost. However, this combination offers safe and reversible immobilization that can be easily administered by the intramuscular route and that produces a plane of anesthesia that is sufficient to carry out most routine diagnostic procedures.     

Evaluation of a butorphanol, detomidine, and midazolam combination for immobilization of captive Nile lechwe antelopes (Kobus magaceros)

Field immobilization of captive antelope may be required for medical examination, blood sample collection, and animal identification. The aim of this study was to evaluate the effects of a combination of butorphanol, detomidine, and midazolam (BDM) and its partial reversibility in Nile lechwe antelope (Kobus megaceros). Nine captive lechwes, weighing 28-64 kg, were immobilized, in February 2011, with butorphanol 0.20 ± 0.05 (mean ± SD) mg/kg, detomidine 0.20 ± 0.05 mg/kg, and midazolam 0.31 ± 0.08 mg/kg administered intramuscularly (IM) with a blowpipe. Physiologic parameters and depth of anesthesia were recorded when the animals became recumbent at 19.55 ± 8.36 min after darting (T0) and after 10 (T10), 20 (T20), and 30 (T30) min. An arterial blood sample was collected at T20. At the end of the procedures, immobilization was partially reversed with atipamezole 0.25 mg/kg IM. Quality of induction, immobilization, and recovery was scored. The BDM combination induced immobilization and lateral recumbency in 13.44 ± 5.61 min. Median induction score (scored 1 [excellent] to 4 [poor]) was 1 (range 1-2). Heart rate varied 40-104 beats/min, respiratory rate 16-108 breaths/min, and rectal temperature 36.5-40.3 C. Hyperthermia was observed and rapidly treated in three animals that demonstrated insufficient immobilization after darting. Arterial blood gas analyses revealed a mean pH of 7.43 ± 0.07, partial arterial pressure of CO(2) of 44.1 ± 6.0 mmHg, partial arterial pressure of O(2) of 74.0 ± 13.5 mmHg, and an arterial O(2) saturation of 94.77 ± 3.96%. Recovery was smooth and animals were walking in 13.44 ± 7.85 min. Median recovery score (1 = excellent to 4 = poor) was 1 (range 1-2). The BDM was effective in immobilizing captive healthy lechwes with minimal cardiorespiratory changes.     

Reversible immobilization of free-ranging African lions (Panthera leo) with medetomidine-tiletamine-zolazepam and atipamezole

A combination of medetomidine-tiletamine-zolazepam was used to conduct six immobilizations of free-ranging lions (Panthera leo) in Waza National Park, Cameroon, during 1999 and 2000. Drugs were administered by dart injection at 0.07+/-0.01 (mean+/-SD) mg/kg of medetomidine and 1.8+/-0.5 mg/kg of tiletamine-zolazepam. Chemical immobilization was characterized by smooth inductions (14.1+/-6 min), satisfactory analgesia, and muscle relaxation. One animal was treated for bradypnea. No major alterations of physiologic parameters (heart and respiratory rates, rectal temperature) were seen during immobilization in the other lions. Relative arterial oxygen saturation was measured in two animals and revealed mild hypoxemia. The animals received atipamezole at 0.3+/-0.1 mg/kg intramuscularly for reversal of anesthesia. Recoveries were uneventful. All animals were radiocollared, and no mortalities occurred during an 18-mo follow-up period. Use of medetomidine-tiletamine-zolazepam for anesthesia and reversal of anesthesia with atipamezole appear to be useful for reversible immobilization of free-ranging lions.     

Field immobilization and euthanasia of American opossum

Seventeen recently trapped opossum, Didelphis virginiana, (median weight 2.45 kg; range = 1.6-5.0 kg; quartiles = 1.8-3.3 kg) were immobilized with either telazol (15 or 30 mg/kg) or a mixture of medetomidine (100 micrograms/kg), butorphanol (0.2 mg/kg), and ketamine HCl (10 mg/kg) based on estimated weights. Anesthetized animals were subjected to cardiac puncture for blood withdrawal and toe pinch. Euthanasia was accomplished by intracardiac administration of 1 ml of concentrated pentobarbital sodium/phenytoin solution. Weights were underestimated for 14 of 17 animals, but were within 0.5 kg of the actual weight. Both drug combinations provided rapid and calm immobilization. Median time to recumbency for the medetomidine-butorphanol-ketamine group (n = 5) was 6 min (range = 4-10 min; quartiles = 6 and 8 min). The median time to recumbency was not statistically different for the low (n = 6) and high dose (n = 6) telazol groups, 3 and 3.5 min respectively (quartiles 3; 3.5 and 4; 5.5 min). The stronger heart beat with telazol immobilization facilitated cardiac puncture. All five animals administered the medetomidine-butorphanol-ketamine mixture and three of six animals given the low telazol dose reacted to cardiac puncture. Only one of six animals given the estimated 30 mg/kg dose of telazol reacted slightly to cardiac puncture. We conclude that 30 mg/kg telazol provides sufficient immobilization and analgesia to allow accurate cardiac puncture of the opossum if the procedure is performed within 5 to 10 min of recumbency. Intracardiac administration of concentrated pentobarbital sodium/phenytoin solution followed by bilateral thoracotomy provides appropriate euthanasia suitable for field situations.     

Immobilization of Himalayan tahr with a xylazine-ketamine mixture and reversal with atipamezole under field conditions

Twenty-nine free-ranging Himalayan tahr (Hemitragus jemlahicus) were darted in the Sagarmatha National Park (Nepal) using different combinations of xylazine and ketamine. Animals in Group 1 (n = 4) received a mean xylazine-ketamine dose of 2.77 +/- 0.99 mg/kg xylazine plus 3.32 +/- 0.19 mg/kg ketamine in males and 2.39 +/- 0.10 mg/kg xylazine plus 4.29 +/- 0.17 mg/kg ketamine in females. Animals in Group 2 (n = 25) received a mean xylazine-ketamine dose of 1.70 +/- 0.41 mg/kg xylazine plus 3.06 +/- 0.74 mg/kg ketamine in males and 1.82 +/- 0.29 mg/kg xylazine plus 3.29 +/- 0.52 mg/kg ketamine in females. No anesthetic-related mortality was recorded. Anesthesia was reversed by a standard dose of 11 mg/animal of atipamezole administered by intramuscular injection. Although all anesthetic dosages immobilized free-ranging tahr successfully, a quick and smooth recovery was obtained (11.1 +/- 5.6 min) only with the dosages of Group 2.     

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.     

Field immobilization of feral 'Judas' donkeys (Equus asinus) by remote injection of medetomidine and ketamine and antagonism with atipamezole

The Judas technique is a method used for landscape control of feral donkeys (Equus asinus) in northern Australia. Central to the success of any Judas program is the safe, efficient, and humane attachment of the telemetry device. For feral donkeys, this involves the use of field immobilization. We examine the replacement of the current chemical capture agent, succinylcholine, with contemporary immobilization agents to achieve positive animal welfare outcomes. A combination of medetomidine and ketamine delivered by remote injection from a helicopter was used to capture 14 free-ranging feral donkeys for the fitting of telemetry collars in Western Australia in November 2010. Dose rates of 0.14 mg/kg medetomidine and 4.1 mg/kg ketamine were appropriate to immobilize animals in 9 min (± SD = 3). Mean recovery time (total time in recumbency) was 21 min (± 14). All animals recovered uneventfully after being administered atipamezole, a specific antagonist of medetomidine, intramuscularly at 0.35 mg/kg. Physiologic parameters were recorded during recumbency, with environment-related hyperthermia being the only abnormality recognized. No significant complications were encountered, and this drug combination represents an efficient approach to capturing wild donkeys. This new method allows a rapid, safe, cost-effective approach to the immobilization of feral donkeys for use as Judas animals. This drug combination will replace the relatively inhumane succinylcholine for the field immobilization of feral donkeys.     

Immobilization of white-tailed deer with telazol,ketamine, and xylazine,and evaluation of antagonists

Telazol–xylazine and ketamine–xylazine are versatile and safe drug combinations that are used frequently for chemical immobilization of cervids. Although neither combination consistently offers rapid induction and recovery, we hypothesized that a combination of Telazol, ketamine, and xylazine (TKX) would provide a safe and effective alternative for immobilization of white-tailed deer (Odocoileus virginianus). During a 2-stage study, we evaluated the effectiveness of yohimbine and tolazoline as alpha₂-adrenergic antagonists (2005–2006), and characterized the factors that affected chemical immobilization of male deer with a targeted dose of telazol (2.20 mg/kg), ketamine (1.76 mg/kg), and xylazine (0.44 mg/kg), using explosive-charged darts (2007–2010). During the first stage, we randomly assigned deer to antagonist treatments, including a control group that did not receive an antagonist (n = 8), a tolazoline (4 mg/kg) treatment (n = 16), and a yohimbine (0.11 mg/kg) treatment (n = 15). Recovery times were longer (P = 0.0013) for control (150.6 ± 21.7 min) and yohimbine (74.5 ± 13.1 min), compared with tolazoline (12.5 ± 12.3 min). Tolazoline resulted in faster and more complete recovery compared with the frequent incomplete antagonism and ataxia observed with yohimbine. During the second stage, 56 immobilization events (2007–2010) with TKX yielded a mean induction time of 7.8 minutes (SE = 0.44). Repeated-measures analyses indicated that induction and recovery were affected by body weight, with larger males taking longer to become recumbent (P = 0.08), but they recovered more rapidly (P = 0.003) following administration of tolazoline. Physiological parameters we measured under anesthesia were within normal ranges for white-tailed deer; however, initial temperature was higher (β = −0.86) for younger males (P = 0.014). Final physiological parameters were closely related to initial measurements, with rectal temperature being the most preserved (β = 0.90); heart and respiration rate declined (β < 0.60) during anesthesia. Our results indicate that TKX may be useful for chemically immobilizing white-tailed deer, and we recommend tolazoline as an antagonist for xylazine. © 2012 The Wildlife Society.     

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.     

Guaiphenesin-ketamine-xylazine infusion to maintain anesthesia in mules undergoing field castration

Background

In order to determine whether a combination of guaiphenesin, ketamine and xylazine can induce safe and satisfactory anaesthesia in mules undergoing field castration, eight healthy adult intact male mules were employed. They were premedicated with intravenous (IV) xylazine (1.3 mg/kg); an additional dose of xylazine (0.3 mg/kg IV) was administered in case of inadequate depth of sedation. Anaesthesia was induced with IV thiopental (6 mg/kg). The quality of sedation and induction was recorded. Anaesthesia was maintained with an infusion of guaiphenesin (50 mg/mL), ketamine (2 mg/mL) and xylazine (1 mg/mL) (GKX). The spermatic cord of each testis was infiltrated with 5 mL of 2% lidocaine. During anaesthesia heart rate (HR), respiratory rate (RR), rectal temperature (RT) and haemoglobin oxygen saturation (SpO₂) were measured every 5 min. The data were analysed with simple one-way analysis of variance (ANOVA). A P value < 0.05 was considered statistically significant. Time of anesthesia, time of surgery and time of recovery were recorded.

Results

Only one mule required an additional dose of xylazine to achieve a satisfactory depth of sedation. Thiopental at the dose of 6 mg/kg IV resulted in smooth induction and lateral recumbency in all animals. GKX provided adequate anaesthesia to perform castration in all mules. Muscle relaxation was deemed adequate and physiological variables remained stable and within references values during the anaesthesia and did not change in response to surgical stimulation. Time (mean ± standard deviation) from the end of the infusion to sternal recumbency and time from sternal recumbency to standing were 27.7 ± 4.6 and 30.1 ± 7.7 min, respectively.

Conclusions

The combination of xylazine, thiopental and GKX provides satisfactory short-term anaesthesia in mules undergoing field castration.

     

A Zoletil-Rompun mixture as an alternative to the use of opioids for immobilization of feral red deer

Sixty chemical immobilizations of red deer (Cervus elaphus hippelaphus) have been carried out during an etho-ecological study from August 1994 to December 1996 in a 35 ha pen in the district of Nitra (Slovac Republic). Our objective was to determine the efficacy and standard dosages of Zoletil and Rompun for the immobilization of adult red deer in feral conditions as an alternative to the use of the highly toxic opioids. We therefore compared an Immobilon-Rompun combination (ImRo) with a 1:1 mixture of Zoletil and Rompun (ZoRo) as an injectable solution. Use of both combinations led to the immobilization of >92% of deer with an injection volume <3 ml. Mean (SD) dose to achieve immobilization was 35 (14) microg/kg ethorphine + 0.14 (0.056) mg/kg acepromazine + 0.36 (0.14) mg/kg xylazine compared to 1.2 (0.8) mg/kg tiletamine + 1.2 (0.8) mg/kg zolazepam + 2.3 (1.6) mg/kg xylazine. This corresponds to a volume of 1.8 (0.7) ml/100 kg body mass (BM) for ImRo (range = 1.0 to 4.6) and to 2.3 (1.6) ml/100 kg BM for ZoRo (range = 0.7 to 4.0), respectively. Heart rate, respiratory rate and oxyhaemoglobin saturation values did not differ significantly between the two groups during immobilization. Three deer (5%) died during immobilization, but fatalities could not be directly associated with the drug effect. Mean (SD) time from darting to complete immobilization was 5.5 (4.2) min for ImRo and 7.5 (6.1) min for ZoRo, respectively. Differences were not statistically significant. Anesthesia with both combinations of immobilizing agents could be reversed within 2 min using sarmazenile-yohimbine for ZoRo and diprenorphine-yohimbine for ImXy immobilizations, respectively. We conclude that the 1:1 combination of Zoletil and xylazine is a valuable alternative to the use of opioids for the immobilization of adult red deer including feral adult animals.     

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.     

Relative efficiency of succinylcholine, xylazine, and carfentanil/xylazine mixtures to immobilize free-ranging moose

We compared the efficiency of succinylcholine chloride, xylazine hydrochloride and carfentanil/xylazine mixtures in immobilizing 364 free-ranging moose (Alces alces) between 1987 and 1997 in Québec (Canada). With succinylcholine chloride (0.070, 0.062, 0.051 mg/kg of estimated body weight for calves, juveniles and adults), 63% of the 252 immobilization attempts led to complete immobilization and marking, whereas 7% of the darted animals died of respiratory paralysis during handling. The moose took an average of 13 min to lay down after darting (down time). Injection of xylazine (3.67-4.22 mg/kg) permitted sedation (the animal laid down but got up again when approached) or complete immobilization in 78% of the 40 darted adult moose, the mean down time being 8.7 min. No mortality was noted with this drug but 58% of the marked animals were only sedated. The use of RX821002A (0.058 mg/kg) as an antagonist, permitted a mean recovery time of 2.8 min after intravenous injection. With the carfentanil/xylazine mixtures (0.0071 and 0.181 mg/kg), 96% of the immobilization trials (n = 72) led to complete (88%) or partial (8%) immobilization, but 6% of the moose died several days after capture. The mean down time was 6.6 min, and injection of naltrexone (0.709 mg/kg) antagonized the effect of the immobilizing agent within 3.7 min. The respiratory rate was higher (P < 0.05) among moose immobilized with xylazine (35/min) than among those immobilized with carfentanil/xylazine mixtures (19/min) but this variation could be related to a longer pursuit time (z = 3.60; P < 0.01) and higher stress levels during handling. Rectal temperature also was higher with xylazine but the difference was small (39.7 vs. 39.3, P = 0.03) and did not differ significantly between the sexes (P > 0.05). Considering loss of materials and helicopter flight time due to non-successful marking trials, carfentanil/xylazine mixtures were the least expensive ($333 Cdn/animal).