- Email: [email protected]
Immobilization of wild giant panda (Ailuropoda melanoleuca) with dexmedetomidine–tiletamine–zolazepam
Veterinary Anaesthesia and Analgesia, 2016, 43, 333–337
doi:10.1111/vaa.12301
SHORT COMMUNICATION
Immobilization of wild giant panda (Ailuropoda melanoleuca) with dexmedetomidine–tiletamine– zolazepam Yipeng Jin*, Yanchao Qiao*, Xiaobin Liu†, Tianchun Pu‡, Hongqian Xu* & Degui Lin* *The Clinical Department, College of Veterinary Medicine, China Agricultural University, Beijing, China †Shaanxi Foping National Reserve, Shaanxi, China ‡Beijing Zoo, Beijing, China
Correspondence: Degui Lin, The Clinical Department, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China. E-mail: [email protected]
Abstract Objective To assess the effects and utility of dexmedetomidine combined with tiletamine and zolazepam (dexMTZ) to immobilize the wild giant panda. Study design Prospective clinical study. Animals Seven giant pandas (Ailuropoda melanoleuca), five males and two females, aged 7–20 years and weighing 69.2–132.9 kg. Methods Once an animal was located, prior data on the individual was reviewed and the panda’s previously estimated body weight was used to calculate the volumes of drugs to administer: dexmedetomidine (dexM; 8 lg kg1; 0.5 mg mL1) and tiletamine–zolazepam (TZ; 2 mg kg1; 50 mg mL1). The mixture was injected intramuscularly (IM) using the Dan-Inject pistol system. When the panda was immobilized, it was weighed, a physical examination was performed and a blood sample collected. Every 5 minutes, the heart rate (HR), respiratory rate (fR), rectal temperature (T), noninvasive systolic arterial pressure (SAP), capillary refill time (CRT), mucous membrane color and pulse quality were recorded. After all procedures had been completed, atipamezole (40 lg kg1) was injected IM.
Results A single injection of dexMTZ resulted in the immobilization of all seven giant pandas. The median (range) of anesthetic agents administered was dexM 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8–2.5 mg kg1). The palpebral reflex was lost 8 (7–12) minutes after the injection. Most of the physiological variables remained in the acceptable range. All procedures were completed in approximately 1 hour. Six out of the seven (85.7%) giant pandas recovered smoothly; one panda had a rough recovery. Conclusions and clinical relevance DexMTZ produced a satisfactory immobilization and a smooth recovery for wild giant pandas while allowing approximately 55 minutes for planned noninvasive procedures. Keywords chemical immobilization, dexmedetomidine, giant panda, tiletamine, zolazepam.
Introduction The giant panda (Ailuropoda melanoleuca) is one of the most endangered species of all land mammals. According to the Third National Survey report on Giant Panda in China, only 275 live in the Mount Qinling area (State Forestry Administration of China 2006). Therefore, it is important to find an effective
333
Chemical immobilization of wild giant panda Y Jin et al.
and safe technique to immobilize pandas for field research. Many injectable anesthetic agent combinations have been used to immobilize bears, of which medetomidine–tiletamine–zolazepam (MTZ) is commonly used. Although in most circumstances the giant panda can be treated as a related species of the Ursidae family, giant pandas and bears have anatomical, physiologic and behavioral differences. Previously published techniques for immobilization of the giant panda include intramuscular (IM) injections of ketamine (Jin et al. 2012), xylazine–ketamine (Kreeger et al. 2002), tiletamine–zolazepam (TZ) (Kreeger et al. 2002) and medetomidine–ketamine (Reed et al. 2013). The aim of this study was to evaluate the behavioral and physiological effects of IM administration of dexmedetomidine–tiletamine–zolazepam (dexMTZ) for the immobilization of seven wild giant pandas. Material and methods All procedures were approved by the China Agriculture University Institutional Animal Care and Use Committee. Between March 2013 and April 2014, seven wild giant pandas were studied in the Qinling area (E107°470 58″, N33°390 6″). These giant pandas had been studied for several years, so a database had been collected at the previous immobilization. The animals were five males and two females, mean standard deviation (SD) 13.9 4.5 years old (range: 7–20) and weighed 95.8 20.8 kg (range: 69.2–132.9). The giant pandas were fitted with Global Positioning System and Very High Frequency (GPS/VHF) collars (Lotek Wireless Inc., ON, Canada) and were located on these devices. When a giant panda was found, the physiologic condition was evaluated by observation from a distance and together with review of the previous database on the individual, a decision was made whether the giant panda could be immobilized. The anesthetic agents were delivered using a remote drug delivery system (Dan-Inject pistol systems; DAN-INJECT ApS, Denmark) with 2.0 9 40 mm collared needles (DAN-INJECT ApS) and 3-mL darts (DAN-INJECT ApS) filled with dexmedetomidine (8 lg kg1; Dexdomitor; Zoetis, Inc., MI, USA) and tiletamine–zolazepam (2 mg kg1; Zoletil 50; Virbac, France). The lateral hip region was chosen as the IM injection site. Once the animal was immobilized, monitoring included heart rate (HR) by counting with a stetho334
scope, hemoglobin O2 saturation via pulse oximetry (SpO2; VE – H100B Veterinary Pulse Oximeter; Edan Instruments, Inc., CA, USA), respiratory rate (fR) by counting thoracic movements, and rectal temperature (T) with a mercury thermometer. Systolic arterial pressure (SAP) was measured noninvasively (Model 811-B; Parks Medical Electronics, Inc., OR, USA) with an adult large cuff width of 21 cm (MDF Instruments, LA, USA) attached to the cubital antebrachial region of the thoracic limb. All values were recorded every 5 minutes by the same person. The depth of anesthesia was assessed according to the palpebral reflex, eyeball position and masseter muscle tone, the induction time was recorded, and an accurate body weight was obtained with a weighing scale. Weight was used to consider if the animal needed additional dexMTZ. Measures were instituted during the anesthetic procedure to prevent hypothermia because of the low ambient temperature (0–7 °C). Warm saline was infused intravenously (IV) at 9–15 mL kg1 hour1, warm water bottles were placed beneath the abdomen, hats were applied to all four feet, and the body was wrapped in a sleeping bag. While immobilized, the giant pandas were weighed, blood samples were collected from the cephalic vein, dental examination and radiography were performed and the GPS collars were serviced. After all the procedures were completed, atipamezole (40 lg kg1; Antisedan; Zoetis, Inc.) was injected IM; a dose rate five times that of dexM. After jaw tone had returned to normal, monitoring was stopped, and all colleagues left the site to make sure that the giant panda recovered in a quiet place. The giant panda was observed until it regained normal mobility and behaved normally. Statistical analysis All data were recorded using a computerized spreadsheet (Microsoft Excel 2011 for Windows Version 7; Microsoft Corporation, WA, USA) and imported into the program for statistical analysis (SAS Version 9.3; SAS Institute, NC, USA). Continuous data were checked for normality of distribution with a Shapiro– Wilk test. Physiological variables between time points were compared using t-test or nonparametric method. Significant differences were analyzed using one-way ANOVA LSD (L) test. Physiological values were reported as mean SD while induction and recovery times were recorded as median (range) in minutes.
© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
Chemical immobilization of wild giant panda Y Jin et al.
Results The initial administration of dexMTZ, reported as median (range) of dexmedetomidine 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8– 2.5 mg kg1), immobilized all seven (100%) giant pandas, and none needed a second dose. After the injection, all the giant pandas stopped eating after 6 (4–9) minutes when jaw movement started slowing down. Giant pandas were asleep, with loss of limb muscle tone and palpebral reflex 8 (7–12) minutes after the injection at which time there was no response to ear pinch and the tongue could easily be pulled out. The duration of immobilization until the administration of atipamezole was 54 (48–70) minutes. During the first 10 minutes, the mucous membrane color was pale, SpO2 was < 90%, mean HR was 56–58 beats minute1 and SAP was > 170
mmHg (Fig. 1). Subsequently, the mucous membrane color became pink, capillary refill time (CRT) improved to ≤ 2 seconds, SpO2 increased to 96 3% (p < 0.05) and SAP decreased to 155 10 mmHg (p = 0.40). HR and fR were unchanged during immobilization (p = 0.61) and (p = 0.93), respectively (Fig. 1). Rectal temperature was initially 37.3 0.3 °C and gradually decreased to 37.0 0.3 °C at the end of immobilization (p = 0.37). After administration of atipamezole, the palpebral reflex had returned in 27 (18–39) minutes and the time to lifting the head in six animals was 42 (31– 59) minutes. In six pandas, recovery was smooth and peaceful, and the pandas were able to stand up on four limbs and move after 51 (36–71) minutes. One male giant panda exhibited fractious behavior, including moving its’ head around, sudden standing up and falling and murmuring during recovery.
Figure 1 The mean standard deviation (SD) for (a) systolic arterial pressure, (b) hemoglobin oxygen saturation (SpO2), (c) heart rate and (d) respiratory rate recorded at 5 minute intervals in seven giant pandas immobilized with median dose rates of 8.4 lg kg1 dexmedetomidine (range: 7.3–10.5) and 2.0 mg kg1 tiletamine-zolazepam (range: 1.8–2.5) using intramuscular injection. n = 7 for all time points except T50 (n = 6), T55 (n = 6) and T60 (n = 6). *Significantly different from SpO2 T15–T60 (p < 0.05). © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
335
Chemical immobilization of wild giant panda Y Jin et al.
Discussion The dexMTZ combination provided satisfactory immobilization in the animals in this study. Combining two or more anesthetic agents may be advantageous over the use of a single anesthetic by reducing the dosage of each of the components which may result in safer immobilization of the animal (Teisberg et al. 2014). Concurrent administration of dexM was reported to reduce the dose of TZ by > 50% in grizzly bears and shortened recovery time (Teisberg et al. 2014). Favorable features of an anesthetic drug combination include shorter induction and recovery times, and less cardiopulmonary depression. As an example, the wild giant pandas in this study were immobilized faster with dexMTZ than two captive pandas immobilized on three occasions with TZ (5.8 1.3 mg kg1), mean 6 minutes compared with 11 minutes, respectively (Mainka & He 1993). Immediately after immobilization and for 10 minutes, the mean SpO2 of the giant pandas in this study was < 90%, which may indicate hypoxemia in some animals. Equipment for measurement of blood gases was not available to confirm the accuracy of the pulse oximetry values. Administration of dexM results in peripheral vasoconstriction and that may have interfered with the acquisition of the pulse oximeter signals. Measurement of arterial partial pressure of oxygen (PaO2) in grizzly bears immobilized with dexMTZ revealed differences between SpO2 and PaO2 and between captive bears and wild bears (Teisberg et al. 2014). PaO2 < 60 mmHg (8.0 kPa) was not measured in any of the 34 animals, although SpO2 < 90% was recorded in six of 24 captive bears but in none of the wild bears. Supplemental oxygen may be advisable for giant pandas developing SpO2 < 90% when immobilized by dexMTZ. fR was little changed throughout immobilization in the giant pandas despite a low then progressive increase in SpO2, indicating that fR is not a reliable monitoring guide for the assessment of adequacy or changes in ventilation in giant pandas. The fR values in this study were lower than reported for giant pandas immobilized with TZ and other injectable combinations (Mainka & He 1993). Further investigation into ventilation and oxygenation of immobilized giant pandas should be performed. Systolic arterial pressure was high during the initial phase of immobilization of the giant pandas. This may have been induced by dexM as a result of 336
stimulation of the a2-receptors in vascular smooth muscle. The following decrease in pressure is explained by the inhibition of central sympathetic outflow and the stimulation of presynaptic a2-receptors (Afonso & Reis 2012). A limitation of the study was the use of noninvasive measurement of blood pressure, and variable accuracy of this technique has been documented in many species. Clipping the thick fur from the giant pandas to improve contact between the cuff and the limb was inadvisable because of the low ambient temperature. However, the trend in SAP was valuable and was paired with frequent palpation of the femoral artery. The HR of the giant pandas immobilized with dexMTZ was less than half that of giant pandas immobilized with TZ (134 9 beats minute1) but closer to that of giant pandas immobilized with xylazine–ketamine (82 26 beats minute1) (Mainka & He 1993). The normal HR of an awake giant panda is unknown; however, the physiological effects of an a2-agonist sedative include decreased HR or bradycardia and the addition of an a2-agonist to TZ is expected to decrease HR in giant pandas as it does in other species of animals. The onset of recovery was initiated by IM injection of atipamezole. Six out of seven pandas recovered smoothly; one became fractious. Multiple factors could have contributed to the poor recovery, such as individual temperament, a difference in metabolizing the anesthetic agents, or incomplete dexM reversal. The atipamezole dose rate chosen for this study was 40 lg kg1, five times the dose of dexM that was administered, and was based on the consideration that an immobilization time of 60 minutes would allow partial metabolism of the dexM. A dose of atipamezole that is 10 times the initial dose of dexM is recommended in some species in situations where rapid and complete reversal is indicated. In a study of the immobilization of wild and captive grizzly bears, overall recovery times were not different when the bears were administered 5- or 10-fold doses of atipamezole (Teisberg et al. 2014). The giant pandas in this study were observed until judged to have regained normal mobility and behavior. However, re-sedation has been reported in other species, and that could threaten the animal’s survival. Whitetailed deer sedated with different dose rates of medetomidine with ketamine and TZ were administered atipamezole at less than 2.8 times the medetomidine dose (equivalent to ≤ 5 times the dexM dose) and re-sedation was observed at 2–4 hours after
© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
Chemical immobilization of wild giant panda Y Jin et al. injection of atipamezole (Muller et al. 2012). This effect may apply to the use of dexM as the clearances of approximately equivalent dose rates of medetomidine and dexM are the same, at least in dogs (Kuusela et al. 2000). Consideration should be given to the appropriate dose of atipamezole for a given situation, and the higher dose may be recommended particularly when additional doses of dexM have been administered to prolong immobilization time. Conclusion The combination of dexM 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8–2.5 mg kg1) administered IM provided 50–70 minutes of satisfactory immobilization of seven wild giant pandas for noninvasive procedures and collection of blood samples. Recovery after administration of atipamezole was smooth in 85.7% of giant pandas. Further investigations should include more detailed physiologic monitoring and extended observation of the recovery period for evidence of complications. Acknowledgements We are grateful to Dr RV Morgan for help in preparation of the manuscript. Also, we would like to thank the colleagues of the Key Lab of Animal Ecology and Conservation Biology of the Chinese Academy Sciences for supporting our research.
References Afonso J, Reis F (2012) Dexmedetomidine: current role in anesthesia and intensive care. Rev Bras Anestesiol 62, 118–133. Jin Y, Lin W, Huang S et al. (2012) Dental abnormalities in eight captive giant pandas (Ailuropoda melanoleuca) in China. J Comp Pathol 146, 357–364. Kreeger T, Arnemo J, Raath J (2002) Handbook of Wildlife Chemical Immobilization. Wildlife Pharmaceuticals, USA. Kuusela E, Raekallio M, Anttila M et al. (2000) Clinical effects and pharmacokinetics of medetomidine and its enantiomers in dogs. J Vet Pharmacol Ther 23, 15–20. Mainka SA, He T (1993) Immobilization of healthy male giant pandas (Ailuropoda melanoleuca) at the Wolong Nature Reserve. J Zoo Wildl Med 24, 430–433. Muller LI, Osborn DA, Doherty T et al. (2012) Optimal medetomidine dose when combined with ketamine and tiletamine-zolazepam to immobilize white-tailed deer. J Wildl Dis 48, 477–482. Reed F, Gregson R, Girling S et al. (2013) Anaesthesia of a captive, male giant panda (Ailuropoda melanoleuca). Vet Anaesth Analg 40, 103–104. State Forestry Administration of China (2006) The Third National Survey Report on Giant Panda in China. Science Press, China. Teisberg JE, Farley SD, Nelson OL et al. (2014) Immobilization of grizzly bears (Ursus arctos) with dexmedetomidine, tiletamine, and zolazepam. J Wildl Dis 50, 74–83. Received 10 January 2015; accepted 24 June 2015.
© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
337
doi:10.1111/vaa.12301
SHORT COMMUNICATION
Immobilization of wild giant panda (Ailuropoda melanoleuca) with dexmedetomidine–tiletamine– zolazepam Yipeng Jin*, Yanchao Qiao*, Xiaobin Liu†, Tianchun Pu‡, Hongqian Xu* & Degui Lin* *The Clinical Department, College of Veterinary Medicine, China Agricultural University, Beijing, China †Shaanxi Foping National Reserve, Shaanxi, China ‡Beijing Zoo, Beijing, China
Correspondence: Degui Lin, The Clinical Department, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China. E-mail: [email protected]
Abstract Objective To assess the effects and utility of dexmedetomidine combined with tiletamine and zolazepam (dexMTZ) to immobilize the wild giant panda. Study design Prospective clinical study. Animals Seven giant pandas (Ailuropoda melanoleuca), five males and two females, aged 7–20 years and weighing 69.2–132.9 kg. Methods Once an animal was located, prior data on the individual was reviewed and the panda’s previously estimated body weight was used to calculate the volumes of drugs to administer: dexmedetomidine (dexM; 8 lg kg1; 0.5 mg mL1) and tiletamine–zolazepam (TZ; 2 mg kg1; 50 mg mL1). The mixture was injected intramuscularly (IM) using the Dan-Inject pistol system. When the panda was immobilized, it was weighed, a physical examination was performed and a blood sample collected. Every 5 minutes, the heart rate (HR), respiratory rate (fR), rectal temperature (T), noninvasive systolic arterial pressure (SAP), capillary refill time (CRT), mucous membrane color and pulse quality were recorded. After all procedures had been completed, atipamezole (40 lg kg1) was injected IM.
Results A single injection of dexMTZ resulted in the immobilization of all seven giant pandas. The median (range) of anesthetic agents administered was dexM 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8–2.5 mg kg1). The palpebral reflex was lost 8 (7–12) minutes after the injection. Most of the physiological variables remained in the acceptable range. All procedures were completed in approximately 1 hour. Six out of the seven (85.7%) giant pandas recovered smoothly; one panda had a rough recovery. Conclusions and clinical relevance DexMTZ produced a satisfactory immobilization and a smooth recovery for wild giant pandas while allowing approximately 55 minutes for planned noninvasive procedures. Keywords chemical immobilization, dexmedetomidine, giant panda, tiletamine, zolazepam.
Introduction The giant panda (Ailuropoda melanoleuca) is one of the most endangered species of all land mammals. According to the Third National Survey report on Giant Panda in China, only 275 live in the Mount Qinling area (State Forestry Administration of China 2006). Therefore, it is important to find an effective
333
Chemical immobilization of wild giant panda Y Jin et al.
and safe technique to immobilize pandas for field research. Many injectable anesthetic agent combinations have been used to immobilize bears, of which medetomidine–tiletamine–zolazepam (MTZ) is commonly used. Although in most circumstances the giant panda can be treated as a related species of the Ursidae family, giant pandas and bears have anatomical, physiologic and behavioral differences. Previously published techniques for immobilization of the giant panda include intramuscular (IM) injections of ketamine (Jin et al. 2012), xylazine–ketamine (Kreeger et al. 2002), tiletamine–zolazepam (TZ) (Kreeger et al. 2002) and medetomidine–ketamine (Reed et al. 2013). The aim of this study was to evaluate the behavioral and physiological effects of IM administration of dexmedetomidine–tiletamine–zolazepam (dexMTZ) for the immobilization of seven wild giant pandas. Material and methods All procedures were approved by the China Agriculture University Institutional Animal Care and Use Committee. Between March 2013 and April 2014, seven wild giant pandas were studied in the Qinling area (E107°470 58″, N33°390 6″). These giant pandas had been studied for several years, so a database had been collected at the previous immobilization. The animals were five males and two females, mean standard deviation (SD) 13.9 4.5 years old (range: 7–20) and weighed 95.8 20.8 kg (range: 69.2–132.9). The giant pandas were fitted with Global Positioning System and Very High Frequency (GPS/VHF) collars (Lotek Wireless Inc., ON, Canada) and were located on these devices. When a giant panda was found, the physiologic condition was evaluated by observation from a distance and together with review of the previous database on the individual, a decision was made whether the giant panda could be immobilized. The anesthetic agents were delivered using a remote drug delivery system (Dan-Inject pistol systems; DAN-INJECT ApS, Denmark) with 2.0 9 40 mm collared needles (DAN-INJECT ApS) and 3-mL darts (DAN-INJECT ApS) filled with dexmedetomidine (8 lg kg1; Dexdomitor; Zoetis, Inc., MI, USA) and tiletamine–zolazepam (2 mg kg1; Zoletil 50; Virbac, France). The lateral hip region was chosen as the IM injection site. Once the animal was immobilized, monitoring included heart rate (HR) by counting with a stetho334
scope, hemoglobin O2 saturation via pulse oximetry (SpO2; VE – H100B Veterinary Pulse Oximeter; Edan Instruments, Inc., CA, USA), respiratory rate (fR) by counting thoracic movements, and rectal temperature (T) with a mercury thermometer. Systolic arterial pressure (SAP) was measured noninvasively (Model 811-B; Parks Medical Electronics, Inc., OR, USA) with an adult large cuff width of 21 cm (MDF Instruments, LA, USA) attached to the cubital antebrachial region of the thoracic limb. All values were recorded every 5 minutes by the same person. The depth of anesthesia was assessed according to the palpebral reflex, eyeball position and masseter muscle tone, the induction time was recorded, and an accurate body weight was obtained with a weighing scale. Weight was used to consider if the animal needed additional dexMTZ. Measures were instituted during the anesthetic procedure to prevent hypothermia because of the low ambient temperature (0–7 °C). Warm saline was infused intravenously (IV) at 9–15 mL kg1 hour1, warm water bottles were placed beneath the abdomen, hats were applied to all four feet, and the body was wrapped in a sleeping bag. While immobilized, the giant pandas were weighed, blood samples were collected from the cephalic vein, dental examination and radiography were performed and the GPS collars were serviced. After all the procedures were completed, atipamezole (40 lg kg1; Antisedan; Zoetis, Inc.) was injected IM; a dose rate five times that of dexM. After jaw tone had returned to normal, monitoring was stopped, and all colleagues left the site to make sure that the giant panda recovered in a quiet place. The giant panda was observed until it regained normal mobility and behaved normally. Statistical analysis All data were recorded using a computerized spreadsheet (Microsoft Excel 2011 for Windows Version 7; Microsoft Corporation, WA, USA) and imported into the program for statistical analysis (SAS Version 9.3; SAS Institute, NC, USA). Continuous data were checked for normality of distribution with a Shapiro– Wilk test. Physiological variables between time points were compared using t-test or nonparametric method. Significant differences were analyzed using one-way ANOVA LSD (L) test. Physiological values were reported as mean SD while induction and recovery times were recorded as median (range) in minutes.
© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
Chemical immobilization of wild giant panda Y Jin et al.
Results The initial administration of dexMTZ, reported as median (range) of dexmedetomidine 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8– 2.5 mg kg1), immobilized all seven (100%) giant pandas, and none needed a second dose. After the injection, all the giant pandas stopped eating after 6 (4–9) minutes when jaw movement started slowing down. Giant pandas were asleep, with loss of limb muscle tone and palpebral reflex 8 (7–12) minutes after the injection at which time there was no response to ear pinch and the tongue could easily be pulled out. The duration of immobilization until the administration of atipamezole was 54 (48–70) minutes. During the first 10 minutes, the mucous membrane color was pale, SpO2 was < 90%, mean HR was 56–58 beats minute1 and SAP was > 170
mmHg (Fig. 1). Subsequently, the mucous membrane color became pink, capillary refill time (CRT) improved to ≤ 2 seconds, SpO2 increased to 96 3% (p < 0.05) and SAP decreased to 155 10 mmHg (p = 0.40). HR and fR were unchanged during immobilization (p = 0.61) and (p = 0.93), respectively (Fig. 1). Rectal temperature was initially 37.3 0.3 °C and gradually decreased to 37.0 0.3 °C at the end of immobilization (p = 0.37). After administration of atipamezole, the palpebral reflex had returned in 27 (18–39) minutes and the time to lifting the head in six animals was 42 (31– 59) minutes. In six pandas, recovery was smooth and peaceful, and the pandas were able to stand up on four limbs and move after 51 (36–71) minutes. One male giant panda exhibited fractious behavior, including moving its’ head around, sudden standing up and falling and murmuring during recovery.
Figure 1 The mean standard deviation (SD) for (a) systolic arterial pressure, (b) hemoglobin oxygen saturation (SpO2), (c) heart rate and (d) respiratory rate recorded at 5 minute intervals in seven giant pandas immobilized with median dose rates of 8.4 lg kg1 dexmedetomidine (range: 7.3–10.5) and 2.0 mg kg1 tiletamine-zolazepam (range: 1.8–2.5) using intramuscular injection. n = 7 for all time points except T50 (n = 6), T55 (n = 6) and T60 (n = 6). *Significantly different from SpO2 T15–T60 (p < 0.05). © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
335
Chemical immobilization of wild giant panda Y Jin et al.
Discussion The dexMTZ combination provided satisfactory immobilization in the animals in this study. Combining two or more anesthetic agents may be advantageous over the use of a single anesthetic by reducing the dosage of each of the components which may result in safer immobilization of the animal (Teisberg et al. 2014). Concurrent administration of dexM was reported to reduce the dose of TZ by > 50% in grizzly bears and shortened recovery time (Teisberg et al. 2014). Favorable features of an anesthetic drug combination include shorter induction and recovery times, and less cardiopulmonary depression. As an example, the wild giant pandas in this study were immobilized faster with dexMTZ than two captive pandas immobilized on three occasions with TZ (5.8 1.3 mg kg1), mean 6 minutes compared with 11 minutes, respectively (Mainka & He 1993). Immediately after immobilization and for 10 minutes, the mean SpO2 of the giant pandas in this study was < 90%, which may indicate hypoxemia in some animals. Equipment for measurement of blood gases was not available to confirm the accuracy of the pulse oximetry values. Administration of dexM results in peripheral vasoconstriction and that may have interfered with the acquisition of the pulse oximeter signals. Measurement of arterial partial pressure of oxygen (PaO2) in grizzly bears immobilized with dexMTZ revealed differences between SpO2 and PaO2 and between captive bears and wild bears (Teisberg et al. 2014). PaO2 < 60 mmHg (8.0 kPa) was not measured in any of the 34 animals, although SpO2 < 90% was recorded in six of 24 captive bears but in none of the wild bears. Supplemental oxygen may be advisable for giant pandas developing SpO2 < 90% when immobilized by dexMTZ. fR was little changed throughout immobilization in the giant pandas despite a low then progressive increase in SpO2, indicating that fR is not a reliable monitoring guide for the assessment of adequacy or changes in ventilation in giant pandas. The fR values in this study were lower than reported for giant pandas immobilized with TZ and other injectable combinations (Mainka & He 1993). Further investigation into ventilation and oxygenation of immobilized giant pandas should be performed. Systolic arterial pressure was high during the initial phase of immobilization of the giant pandas. This may have been induced by dexM as a result of 336
stimulation of the a2-receptors in vascular smooth muscle. The following decrease in pressure is explained by the inhibition of central sympathetic outflow and the stimulation of presynaptic a2-receptors (Afonso & Reis 2012). A limitation of the study was the use of noninvasive measurement of blood pressure, and variable accuracy of this technique has been documented in many species. Clipping the thick fur from the giant pandas to improve contact between the cuff and the limb was inadvisable because of the low ambient temperature. However, the trend in SAP was valuable and was paired with frequent palpation of the femoral artery. The HR of the giant pandas immobilized with dexMTZ was less than half that of giant pandas immobilized with TZ (134 9 beats minute1) but closer to that of giant pandas immobilized with xylazine–ketamine (82 26 beats minute1) (Mainka & He 1993). The normal HR of an awake giant panda is unknown; however, the physiological effects of an a2-agonist sedative include decreased HR or bradycardia and the addition of an a2-agonist to TZ is expected to decrease HR in giant pandas as it does in other species of animals. The onset of recovery was initiated by IM injection of atipamezole. Six out of seven pandas recovered smoothly; one became fractious. Multiple factors could have contributed to the poor recovery, such as individual temperament, a difference in metabolizing the anesthetic agents, or incomplete dexM reversal. The atipamezole dose rate chosen for this study was 40 lg kg1, five times the dose of dexM that was administered, and was based on the consideration that an immobilization time of 60 minutes would allow partial metabolism of the dexM. A dose of atipamezole that is 10 times the initial dose of dexM is recommended in some species in situations where rapid and complete reversal is indicated. In a study of the immobilization of wild and captive grizzly bears, overall recovery times were not different when the bears were administered 5- or 10-fold doses of atipamezole (Teisberg et al. 2014). The giant pandas in this study were observed until judged to have regained normal mobility and behavior. However, re-sedation has been reported in other species, and that could threaten the animal’s survival. Whitetailed deer sedated with different dose rates of medetomidine with ketamine and TZ were administered atipamezole at less than 2.8 times the medetomidine dose (equivalent to ≤ 5 times the dexM dose) and re-sedation was observed at 2–4 hours after
© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia, 43, 333–337
Chemical immobilization of wild giant panda Y Jin et al. injection of atipamezole (Muller et al. 2012). This effect may apply to the use of dexM as the clearances of approximately equivalent dose rates of medetomidine and dexM are the same, at least in dogs (Kuusela et al. 2000). Consideration should be given to the appropriate dose of atipamezole for a given situation, and the higher dose may be recommended particularly when additional doses of dexM have been administered to prolong immobilization time. Conclusion The combination of dexM 8.4 lg kg1 (7.3–10.5 lg kg1) and TZ 2.0 mg kg1 (1.8–2.5 mg kg1) administered IM provided 50–70 minutes of satisfactory immobilization of seven wild giant pandas for noninvasive procedures and collection of blood samples. Recovery after administration of atipamezole was smooth in 85.7% of giant pandas. Further investigations should include more detailed physiologic monitoring and extended observation of the recovery period for evidence of complications. Acknowledgements We are grateful to Dr RV Morgan for help in preparation of the manuscript. Also, we would like to thank the colleagues of the Key Lab of Animal Ecology and Conservation Biology of the Chinese Academy Sciences for supporting our research.
References Afonso J, Reis F (2012) Dexmedetomidine: current role in anesthesia and intensive care. Rev Bras Anestesiol 62, 118–133. Jin Y, Lin W, Huang S et al. (2012) Dental abnormalities in eight captive giant pandas (Ailuropoda melanoleuca) in China. J Comp Pathol 146, 357–364. Kreeger T, Arnemo J, Raath J (2002) Handbook of Wildlife Chemical Immobilization. Wildlife Pharmaceuticals, USA. Kuusela E, Raekallio M, Anttila M et al. (2000) Clinical effects and pharmacokinetics of medetomidine and its enantiomers in dogs. J Vet Pharmacol Ther 23, 15–20. Mainka SA, He T (1993) Immobilization of healthy male giant pandas (Ailuropoda melanoleuca) at the Wolong Nature Reserve. J Zoo Wildl Med 24, 430–433. Muller LI, Osborn DA, Doherty T et al. (2012) Optimal medetomidine dose when combined with ketamine and tiletamine-zolazepam to immobilize white-tailed deer. J Wildl Dis 48, 477–482. Reed F, Gregson R, Girling S et al. (2013) Anaesthesia of a captive, male giant panda (Ailuropoda melanoleuca). Vet Anaesth Analg 40, 103–104. State Forestry Administration of China (2006) The Third National Survey Report on Giant Panda in China. Science Press, China. Teisberg JE, Farley SD, Nelson OL et al. (2014) Immobilization of grizzly bears (Ursus arctos) with dexmedetomidine, tiletamine, and zolazepam. J Wildl Dis 50, 74–83. Received 10 January 2015; accepted 24 June 2015.
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