Immobilization of Captive Wapiti Cervus canadensis with Azaperone and Xylazine

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1 Notes Immobilization of Captive Wapiti Cervus canadensis with Azaperone and Xylazine Jamie L. Stewart,* Danielle E. Strahl-Heldreth, Clifford F. Shipley J.L. Stewart, D.E. Strahl-Heldreth, C.F. Shipley Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, Illinois Present address of J.L. Stewart: Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia Abstract Xylazine, an a2-adrenoreceptor agonist, is commonly used in combination with other drugs for safe and effective immobilization of North American wapiti Cervus canadensis. Azaperone is a neuroleptic sedative that reduces the stress of immobilization and handling, but there are no reports of its efficacy when combined with xylazine for use in wapiti. Our objective was to test the efficacy of a combination of xylazine and azaperone to remotely immobilize captive wapiti for performing routine procedures. We administered drugs intramuscularly using a CO 2 -powered projector with commercially made darts. We successfully immobilized 11 of 12 wapiti with one remote injection containing estimated doses of mg/kg xylazine and mg/kg azaperone (mean 6 SD), and immobilized animals were recumbent at 2 12 min after injection (mean: 6 min 40 s). We administered tolazoline as a reversal for xylazine at an estimated dose of mg/kg intramuscularly, and all wapiti were standing within 14 min of reversal administration. In a subset of three wapiti, a moderate hypoxemia occurred immediately after immobilization but resolved by 60 min, before xylazine reversal. The combination of xylazine and azaperone resulted in smooth and safe immobilization for performing routine processing in captive North American wapiti. Further studies are needed to determine whether this combination and dose of drugs would be sufficient for immobilization of free-ranging wapiti. Keywords: a2 agonist; azaperone; Cervus canadensis; elk; immobilization; tranquilizer; xylazine Received: March 23, 2018; Accepted: September 17, 2018; Published Online Early: October 2018; Published: December 2018 Citation: Stewart JL, Strahl-Heldreth DE, Shipley CF Immobilization of captive wapiti Cervus canadensis with azaperone and xylazine. Journal of Fish and Wildlife Management 9(2): ; e x. doi: / JFWM-025 Copyright: All material appearing in the Journal of Fish and Wildlife Management is in the public domain and may be reproduced or copied without permission unless specifically noted with the copyright symbol &. Citation of the source, as given above, is requested. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. * Corresponding author: jlstewart13@vt.edu Introduction North American wapiti Cervus canadensis, also known as elk, is one of the largest species within the Cervidae family. Captive and free-ranging populations of wapiti are highly prevalent, warranting the need for a quick and safe immobilization protocol for implementing routine herd health, diagnostic, and disease monitoring programs (Corn and Nettles 2001; Hattel et al. 2007). One of the earliest reports for immobilizing wapiti described the use of carfentanil, an ultrapotent morphine-like agent belonging to the fentanyl family of narcotics (Meuleman et al. 1984). Although an effective immobilization agent, carfentanil limitations include a 5 10% incidence of renarcotization in ungulates after reversal (Allen 1989) and life-threatening hazards to humans if handled inappropriately (George et al. 2010). Different combinations of drugs have also been reported to be effective in wapiti that include another potent opioid, etorphine hydrochloride/m99 (Magonigle et al. 1977), ketamine xylazine (Golightly and Hofstra 1989), and xylazine tiletamine zolazepam (Read et al. 2001). Both tiletamine Journal of Fish and Wildlife Management December 2018 Volume 9 Issue 2 631

2 and ketamine are dissociative anesthetics that run the risk of causing convulsive activity and rigidity if not administered with tranquilizers or if reversal occurs too quickly (Caulkett 1997). For routine preventative procedures (blood testing, deworming, vaccinations, deantlering), the use of a dissociative anesthetic to induce a deep plane of anesthesia is usually not necessary and introduces the risk of causing aspiration pneumonia, respiratory arrest, and/or death (Carroll and Hartsfield 1996). In free-ranging Rocky Mountain elk Cervus canadensis nelsoni, a combination of butorphanol, azaperone, and medetomidine has been described as a safe and effective immobilization agent (Wolfe et al. 2014a). Butorphanol is a partial opiate agonist that contains both analgesic and sedative properties and can be reversed with naltrexone (Wolfe et al. 2014a). Azaperone is a short-acting neuroleptic sedative that can reduce stress from capturing and handling in combination with other drugs (Caulkett and Arnemo 2014). The final component, medetomidine, is a potent a2-adrenoreceptor agonist that has effective sedative and analgesic properties and allows for good muscle relaxation, but it can also be easily reversed (Wolfe et al. 2014a). Although one article reported that medetomidine and azaperone in combination were insufficient for handling free-ranging Rocky Mountain elk (Wolfe et al. 2014b), another article reported that a combination of 1 mg/kg body weight (BW) of a different a2-adrenoreceptor agonist, xylazine, and 0.1 mg/kg BW azaperone is effective for sedation in wapiti (Caulkett 1997). However, there is a lack of published data to support the use of this combination of xylazine and azaperone alone for immobilization in captive wapiti. Therefore, the goal of this project was to determine the efficacy and safety of a combination of xylazine and azaperone for immobilizing captive North American wapiti by 1) recording induction and reversal times and 2) measuring temporal physiological responses of arterial blood gas and electrolyte parameters to immobilization. Methods Study site To avoid unnecessary immobilization, data were collected opportunistically during routine processing of Rocky Mountain wapiti performed at two separate facilities in Illinois. Techniques were consistent with guidelines approved by the American Society of Mammalogists (Sikes 2016). The first round of immobilization occurred November 2016 at the Busse Woods Forest Preserve in Elk Grove, Illinois, USA. The small wapiti herd (n ¼ 6) at this facility inhabit a 17-acre (6.8-ha) enclosed pasture and had previously tested negative for both Brucella abortus and Mycobacterium bovis. Wapiti were moved to a m holding pen and remotely immobilized in succession. The second round of immobilization occurred February 2017 at a privately owned facility in east central Illinois. These captive wapiti (n ¼ 6) are rotated throughout an 8-acre enclosed pasture and previously tested negative for Brucella abortus and Mycobacterium bovis. The second set of wapiti were moved to a m holding pen and remotely immobilized in succession. Three female wapiti from the second herd were immobilized August 2017 for pregnancy diagnosis via rectal palpation, during which physiological parameters were monitored. All wapiti were approached and darted from no farther than 10-m distance. Wapiti and immobilization procedure We immobilized wapiti (n ¼ 7 adult females, n ¼ 4 adult males, n ¼ 1 male calf) at both facilities within the natural breeding season (September February). Xylazine hydrochloride was dosed at 400 mg for bulls (1 ml, 300 mg/ml; Zoopharm, Windsor, CO; 1 ml, 100 mg/ml; AnaSed LA, VetOnet, Boise, ID), 300 mg for cows (1 ml, 300 mg/ml; Zoopharm), and 125 mg for an approximately 6-mo-old calf (1.25 ml, 100 mg/ml; AnaSed LA, VetOne). Azaperone tartrate (50 mg/ml; Zoopharm) was dosed at 50 mg for all adult animals and at 15 mg for the calf. Using estimated animals weights based on clinical experience, dosages were calculated to be approximately 1.3 mg of xylazine per kilogram of BW (1.3 mg/kg BW) and 0.2 mg/kg BW azaperone (Table 1). All injections were delivered remotely to the quadriceps musculature by an experienced clinician using powder-charge darts (3.0 ml for bulls and 2.0 ml for cows and calf) with gel collars with 1.25-in. (3.2-cm) needles (Pneu-Dart Inc., Williamsport, PA) fired from a CO 2 -powered rifle (X- Caliber TM ; Pneu-Dart Inc.). We monitored initiation of immobilization (minutes), defined as the time from remote injection until the head began to drop, and induction time (minutes), defined as the time from remote injection until the animal was completely down and able to be approached. When wapiti were approached, towels were placed over their eyes to minimize visual stimulus. During immobilization, we recorded heart rate via thoracic auscultation (beats per minute), respiratory rate by visual examination of thoracic movement (breaths per minute), and rectal temperature with a digital thermometer (Celsius). We performed routine processing of all wapiti during the period of immobilization. Processing included administration of vaccines against common bacterial (Covexin 8; Merck, Kenilworth, NJ) and respiratory (Vira Shieldt 6; Elanco, Greenfield, IN) pathogens subcutaneously and a topical dewormer (Cydectin; Bayer Corporation, Whippany, NJ). In November, antlers also were removed from bulls by using an electric saw. We performed venipuncture in all animals in the February collection and one animal in the November collection for routine herd screening. After completing the procedures, we administered tolazoline hydrochloride (100 mg/ml, Tolazinet HCl; Akorn, Inc., Lake Forest, IL) intramuscularly at 1,200 mg for larger bulls, 900 mg for smaller bulls and cows, and 300 mg for the calf. We administered an extra 400 mg of Journal of Fish and Wildlife Management December 2018 Volume 9 Issue 2 632

3 Table 1. Animal information, estimated dosing regimen, and vital physiological data for remote administration of xylazine and azaperone to captive North American wapiti Cervus canadensis. Vitals all were within normal limits throughout immobilization. Animal Age no. Sex b (y) Month Xylazine (mg) Azaperone (mg) Xylazine (mg/kg) a Azaperone (mg/kg) a Rectal temp. (8C) Heart rate (beats/min) Respiratory rate (breaths/min) 1 M 4.5 November M 2.5 November M 2.5 November M 6.5 February M 0.5 November F 4.5 November F 4.5 November F 2.5 February F 2.5 February F 2.5 February F 10.5 February F 12.5 February Mean 6 SD a Doses based on estimate weight of 325 kg for males, 225 kg for females, and 100 kg for the calf. b M ¼ male; F ¼ female. tolazoline to one bull (total 1,600 mg) after he did not respond to the initial dose. Using estimated animal weights, we administered the approximate dose of tolazoline 3 mg/kg BW (Table 2). We recorded recovery time (minutes) from the time of reversal administration until the animal was standing. After determining the efficacy of using this xylazine and azaperone protocol, we used the same protocol (300 mg of xylazine plus 50 mg of azaperone) to immobilize a subset of three mature female wapiti (ages 3 10 y) for routine pregnancy diagnosis via rectal palpation. To better evaluate physiological responses to the drugs, we obtained an anaerobic 1-mL blood sample from the medial auricular artery at 0, 30, and 60 min after the wapiti were completely immobilized. We measured blood gases by using a portable analyzer (VetScan i- STAT 1; Abbott Point of Care Inc., Union City, CA), and determined lactate by using a handheld lactometer (Lactate Plus meter; Nova Biomedical, Waltham, MA). We performed drug reversal as previously described with 900 mg of tolazoline, and recovery was uneventful. Results All data are presented as mean 6 standard deviation (SD). In total, we successfully immobilized 11 (92%) of 12 wapiti with an estimated dose of mg/kg xylazine and mg/kg azaperone administered intramuscularly (Table 1). For these 11 wapiti, we noted initial signs of immobilization (head drop) at a mean of 5 min 49 s (range: 2 9 min), and achieved complete immobilization at a mean of 6 min 40 s (range: 2 12 min; Table 2). The remaining adult female required a second dart that contained 200 mg of xylazine and was successfully immobilized within 5 min (Table 2). Heart rate, respiratory rate, and rectal temperature (Table 1) were within recommended limits for this species Table 2. Timing of immobilization and reversal after remote administration of a combination of xylazine (estimated 1.3 mg/kg a ) and azaperone (estimated 0.2 mg/kg a ) to captive North American wapiti Cervus canadensis. We achieved reversal using tolazoline. Time of dart administration is considered to be 0 h. Animal no. Darted (hours) Head drop Down Additional xylazine (200 mg) Head drop Down Reversal time Tolazoline (mg) Tolazoline (mg/kg a ) Standing after reversal :03:17 0:04:47 0:52:00 1, :10: :03:16 0:04:46 0:48: :14: :06:00 0:08:22 0:52: :10: :05:00 0:08:00 1:09:00 1, :07: :03:08 0:05:06 0:49: :13: :03:30 0:05:14 0:49: :13: :08:42 0:17:32 0:18:57 0:22:12 0:50: :12: :05:00 0:12:00 1:08: :06: :07:00 0:10:00 1:08: :09: :03:00 0:04:00 1:06: :05: :02:00 0:02:00 1:04: :04: :08:00 0:09:00 1:00: :03:00 Mean 0:05:49 0:06:40 0:57: :08:50 SD 0:02:05 0:02:52 0:08: :08:37 a Doses based on estimate weight of 325 kg for males, 225 kg for females, and 100 kg for the calf. Journal of Fish and Wildlife Management December 2018 Volume 9 Issue 2 633

4 Table 3. Arterial gas and electrolyte index values for three captive female wapiti Cervus canadensis immobilized with 300 mg of xylazine and 50 mg of azaperone administered via projector over 60 min before reversal with tolazoline. Means reported with SD. We immediately observed a moderate hypoxemia via hypoventilation and ventilation-perfusion mismatch as depressed partial pressure of arterial oxygen (PaO 2 ) and increased partial pressure of arterial carbon dioxide (PaCO 2 ). However, the depressed PaO 2 resolved by 60 min, before reversal. The remaining physiological parameters of these immobilized wapiti cows remained relatively stable throughout the collection period. Parameter a Sodium, Na þ (mmol/l) Potassium, K þ (mmol/l) Ionized calcium (mmol/l) Glucose (mg/dl) Hematocrit (%) ph PaCO 2 (mmhg) PaO 2 (mmhg) TCO 2 (mmol/l) Bicarbonate (mmol/l) Base excess (mmol/l) so 2 (%) Hemoglobin (mmol/l) Lactate (mmol/l) (Caulkett and Arnemo 2014). We administered tolazoline intramuscularly at an estimated dose of mg/kg with wapiti standing at a mean of 8 min 50 s (range: 3 14 min) after reversal administration (Table 2). In the three wapiti used for measuring arterial blood gas and electrolytes, we immediately observed a moderate hypoxemia via hypoventilation and ventilation-perfusion mismatch as depressed partial pressure of arterial oxygen and increased partial pressure of arterial carbon dioxide (Table 3). However, the depressed partial pressure of arterial oxygen resolved by 60 min, before reversal. The remaining physiological parameters of these immobilized wapiti cows remained relatively stable throughout the collection period (Table 3). Discussion Time (min) a TCO 2 ¼ total carbon dioxide; so 2 ¼ oxygen saturation of hemoglobin molecules. We found that a combination of xylazine and azaperone was safe and effective for immobilization of captive North American wapiti. The estimated doses reported in the current study were chosen based on clinical experiences of one author (CFS) and are slightly higher than those suggested previously for captive wapiti (Caulkett 1997) at 1.3 mg/kg xylazine and 0.2 mg/kg azaperone vs. 1 and 0.1 mg/kg, respectively. A major advantage of using this combination of drugs in both captive and wild wapiti, where weight is generally estimated, is their wide safety margin (Walter et al. 2005; Wolfe et al. 2014a). Doses of 0.11, 0.17, and 0.22 mg/kg azaperone were previously used in combination with low, medium, and high doses of butorphanol and medetomidine, with transient hypoxemia reported in all wapiti that resolved after medetomidine reversal (Wolfe et al. 2014a). Another study reported no apparent side effects with up to 3 mg/kg xylazine administered remotely in conjunction with tiletamine and zolazepam (Telazolt; Fort Dodge Laboratories, Inc., Fort Dodge, IA) to free-ranging wapiti (Walter et al. 2005). The doses required to immobilize wapiti seem to be affected by individual animal physiology and behavior, which may be why another author reported insufficient immobilization with medetomidine and azaperone in free-ranging wapiti (Wolfe et al. 2014b). By contrast, no differences in induction time were detected between darted captive and free-ranging wapiti in another study with sufentanil (a potent opioid) and xylazine (Kreeger et al. 2011). Although all of the animals in the current study were considered to be captive rather than free ranging, the wapiti were not handled on a regular basis and were increasingly excited by the initiation of darting within each group. Regardless, further work is necessary to determine whether the estimated doses of xylazine and azaperone evaluated in this study would be sufficient for immobilization of free-ranging wapiti populations. Quick immobilization induction times help to minimize stress and reduce the risks of injury, hyperthermia, and capture myopathy (Paterson 2007). The mean induction time of 6 min 40 s reported in the current study is faster than those reported in captive and freeranging wapiti with xylazine tiletamine zolazepam (~10 min; Read et al. 2001) and free-ranging wapiti with acepromazine medetomidine (7 15 min; Wolfe et al. 2014b), but comparable to those reported for captive wapiti with butorphanol azaperone medetomidine (5 7 min; Wolfe et al. 2014a). Induction time in captive and free-ranging wapiti treated with 0.1 mg/kg sufentanil and 0.5 mg/kg xylazine was reportedly lower at 4.4 and 5.1 min, respectively (Kreeger et al. 2011). Although opioids are equally to more effective at reducing induction times than azaperone, they are controlled substances that require strict regulations in regard to storage, record keeping, and handling protocols. In addition, reported side effects with opioids include hyperthermia, poor muscle relaxation, and prolonged recoveries if not reversed (Caulkett et al. 2000). These results suggest that the addition of azaperone seems to be a safe alternative to opioids to reduce the induction time in captive wapiti. Another advantage of the xylazine azaperone immobilization protocol over others is the ability to antagonize the xylazine with tolazoline, while allowing the azaperone to persist with its sedative effects to reduce stress upon recovery in captive animals. Reported dosages for tolazoline administration in wapiti have ranged from 2 mg/kg (Kreeger et al. 2011) to 4 mg/kg (Walter et al. 2005). The estimated dose of 3 mg/kg tolazoline used in the current study appeared to be sufficient, with wapiti standing at a mean of 8 min 50 s after reversal at a range of 3 14 min. This recovery time is similar to reports of 7 12 min with butorphanol Journal of Fish and Wildlife Management December 2018 Volume 9 Issue 2 634

5 azaperone medetomidine (Wolfe et al. 2014a) but prolonged in comparison to the 3.9 min reported with sufentanil and xylazine (Kreeger et al. 2011). The prolonged recovery time is likely due to the persistence of azaperone, since both sufentanil and xylazine were previously reversed (Kreeger et al. 2011). The sedative effects of azaperone allow for a less stressful recovery from anesthetics and may outweigh the benefits of a faster, but more stressful, recovery in captive populations. Further studies in free-ranging populations may be necessary to determine whether the prolonged recovery time and subsequent sedation affects the ability of wapiti to escape predators or whether continuous monitoring would be required. Normal arterial oxygen tension in ruminants is greater than 80 mmhg, and supplementation with oxygen is recommended while under anesthesia due to the risk of hypoxia (Carroll and Hartsfield 1996; Fahlman et al. 2014). Although we detected a transient hypoxemia immediately after immobilization in the current report, it was resolved by 60 min postimmobilization and did not seem to affect recovery. In addition, the observed hypoxemia in the current report was less pronounced than that described in wapiti immobilized with xylazine tiletamine zolazepam at 70 vs mmhg, respectively (Read et al. 2001). In this previous report, hypoxemia was successfully managed by simply supplementing with 5 min of nasal insufflation of oxygen at 10 L/min (Read et al. 2001). However, although improved arterial blood gas values may occur, supplemental oxygen increases the risk of causing prolonged periods of apnea and moderate-to-severe hypercarbia and respiratory acidosis in immobilized wapiti (Paterson et al. 2009). Therefore, since the hypoxia observed was transient and resulted in a normal recovery, oxygen supplementation seems unnecessary for use with the current protocol for short, routine procedures in wapiti. Acknowledgments We thank the staff at the Busse Woods Forest Preserve in Elk Grove, Illinois, for allowing us to use and publish data collected during routine wapiti processing. We also acknowledge University of Illinois clinical year veterinary students Samantha Scholz and Andrew Lee for assisting with data collection. Funding for this project was provided internally. The authors would also like to extend their utmost gratitude to the Associate Editor and reviewers for their invaluable input that greatly improved the final version of this manuscript. Any use of trade, product, website, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. References Allen JL Renarcotization following carfentanil immobilization of nondomestic ungulates. Journal of Zoo and Wildlife Medicine 20: Carroll GL, Hartsfield SM General anesthetic techniques in ruminants. Elsevier Masson SAS. 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6 Sikes RS Guidelines of the American Society of Mammalogists for the use of wild mammals in research and education. Journal of Mammalogy 97: Walter WD, Leslie DM Jr, Herner-Thogmartin JH, Smith KG, Cartwright ME Efficacy of immoblizing freeranging elk with Telazolt and xylazine hydrochloride using trasnmitter-equipped darts. Journal of Wildlife Diseases 41: Wolfe LL, Fisher MC, Davis TR, Miller MW. 2014a. Efficacy of a low-dosage combination of butorphanol, azaperone, and medetomidine (BAM) to immobilize Rocky Mountain elk. Journal of Wildlife Diseases 50: Wolfe LL, Johnson HE, Fisher MC, Sirochman MA, Kraft B, Miller MW. 2014b. Use of acepromazine and medetomidine in combination for sedation and handling of Rocky Mountain elk (Cervus elaphus nelsoni) and black bears (Ursus americanus). Journal of Wildlife Diseases 50: Journal of Fish and Wildlife Management December 2018 Volume 9 Issue 2 636