Novel combinations of nalbuphine and medetomidine for wildlife immobilization

Comparison of Ketamine-Xylazine, Butorphanol-Azaperone-Medetomidine, and Nalbuphine-Medetomidine-Azaperone for Raccoon (Procyon lotor) Immobilization

Raccoons (Procyon lotor) are frequently handled using chemical immobilization in North America for management and research. In a controlled environment, we compared three drug combinations: ketamine-xylazine (KX), butorphanol-azaperone-medetomidine (BAM), and nalbuphine-medetomidine-azaperone (NalMed-A) for raccoon immobilization. In crossover comparisons, raccoons received a mean of the following: 8.66 mg/kg ketamine and 1.74 mg/kg xylazine (0.104 mL/kg KX); 0.464 mg/kg butorphanol, 0.155 mg/kg azaperone, and 0.185 mg/kg medetomidine (0.017 mL/kg BAM); and 0.800 mg/kg nalbuphine, 0.200 mg/kg azaperone, and 0.200 mg/kg medetomidine (0.020 mL/kg NalMed-A). Induction time was shortest with KX (mean±SE, 10.0±0.7 min) and longest with NalMed-A (13.0±1.3 min). A sampling procedure was completed on 89% (16/18), 72% (13/18), and 89% (16/18) of the raccoons administered KX, BAM, and NalMed-A, respectively. Reasons for incomplete sampling included inadequate immobilization (one KX and one NalMed-A), responsive behaviors (one each with KX, BAM, NalMed-A), or animal safety (four BAM). Mean recovery time for KX was 32.8±7.1 min without antagonizing and 28.6±5.2 min following delivery of an antagonist. Mean recovery time was 6.2±0.8 min for BAM and 5.1±0.5 min for NalMed-A after antagonizing. Only with KX were raccoons observed to recover without use of an antagonist. Supplemental oxygen was provided to 23% (3/13), 72% (13/18), and 71% (12/17) of raccoons immobilized with KX, BAM, and NalMed-A, respectively. Hypoxemia at <80% oxygen saturation occurred in 0% (0/17), 27% (4/15), and 6% (1/16) of the raccoons administered KX, BAM, and NalMed-A, respectively; all raccoons fully recovered from chemical immobilization. All combinations could be used for raccoon immobilization; however, the need for delivery of supplemental oxygen to a majority of raccoons immobilized with BAM and NalMed-A may limit broader use of these agents for certain field studies involving capture, sample, and release of free-ranging animals from a practical standpoint.

A MIXTURE OF NALBUPHINE, AZAPERONE, AND MEDETOMIDINE FOR IMMOBILIZING RINGTAILS (BASSARISCUS ASTUTUS)

We evaluated a combination of nalbuphine HCl (40 mg/mL), azaperone tartrate (10 mg/mL), and medetomidine HCl (10 mg/mL), a combination known as NAM or NalMed-A, in 23 ringtails (Bassariscus astutus) during 29 handling events for a radio-collaring study in southern Oregon, US, from August 2020 to March 2022. The combination was delivered to ringtails by hand injection at 0.075 mL NAM per estimated 1 kg body mass. The mean (± standard deviation, SD) dosage calculated post hoc was 3.366 (±0.724) mg/kg nalbuphine, 0.841 (±0.181) mg/kg medetomidine, and 0.841 (±0.181) mg/kg azaperone. All captured ringtails were effectively immobilized with a mean (SD) induction time of 13.24 (±3.57) min. The medetomidine and nalbuphine components were antagonized with a combination of atipamezole and naltrexone HCl with a mean (SD) recovery time of 2.48 (±1.94) min. This combination appeared to be safe and effective for immobilizing ringtails with a low volume dose, smooth antagonism, and rapid recovery. In addition, NAM does not contain any drugs that are US Drug Enforcement scheduled, which makes it useful for immobilization procedures by wildlife professionals in the US.

Immobilization of Raccoons (Procyon lotor) with Nalbuphine, Medetomidine, and Azaperone

Chemical immobilization is widely used by wildlife and veterinary professionals for the safe handling of animals. A combination of nalbuphine (40 mg/mL), azaperone (10 mg/mL), and medetomidine (10 mg/mL), known as NAM, is a low-volume combination with field immobilization practicality and fewer regulations restricting its use in the US than some other drug combinations. We evaluated the safety and effectiveness of NAM as an immobilizing agent for raccoons (Procyon lotor). From May 2021 to February 2022, 16 adult raccoons were captured in cage traps and immobilized with 0.3 mL NAM intramuscularly (12 mg nalbuphine, 3 mg medetomidine, and 3 mg azaperone, regardless of body weight). After administration, time to sedation was measured; body temperature, heart rate, respiratory rate, and oxygen saturation were monitored and recorded every 5 min for 20 min. Each raccoon was weighed; the dose administered was calculated (range 2.2-4.1 mg/kg, mean 3 mg/kg). Mean induction time was 6 min (4-17 min); time to recovery following administration of 15 mg atipamezole, 7.5 mg naltrexone for reversal, was 10 min (6-18 min). Heart rate, oxygen saturation, and respiration rate remained steady during immobilization. Rectal temperature steadily declined. Overall, NAM appeared to be a practical option for raccoon immobilization, providing rapid induction and reversal as well as adequate sedation for short-term handling and minimally invasive sampling.

Safety and Efficacy of Nalbuphine, Medetomidine, and Azaperone for Immobilizing Aoudad (Ammotragus lervia)

We evaluated the safety and efficacy of nalbuphine (40 mg/mL), plus medetomidine (10 mg/mL), plus azaperone (10 mg/mL) under the premixed label NalMed-A. From January to March 2020, 10 aoudad (Ammotragus lervia) were immobilized via dart-gun for seven separate sampling periods for a total of 45 recorded individual immobilization events. Induction and reversal times with NalMed-A were 5.53±2.61 min and (following atipamezole administration) 5.08±2.43 min while previous studies with alpha-2 agonist-ketamine combinations gave median and average induction times of 4.6 min and 11.2 min using medetomidine-ketamine and xylazine-ketamine, respectively. Overall, NalMed-A adequately immobilized aoudad, with 13% incidence of hyperthermia and 2.22% mortality when delivered via dart.

Apparent stability masks underlying change in a mule deer herd with unmanaged chronic wasting disease

The contagious prion disease "chronic wasting disease" (CWD) infects mule deer (Odocoileus hemionus) and related species. Unchecked epidemics raise ecological, socioeconomic, and public health concerns. Prion infection shortens a deer's lifespan, and when prevalence (proportion of adults infected) becomes sufficiently high CWD can affect herd dynamics. Understanding population responses over time is key to forecasting long-term impacts. Here we describe unexpected stability in prevalence and abundance in a mule deer herd where CWD has been left unmanaged. High apparent prevalence (~30%) since at least 2005 likely drove observed changes in the proportion and age distribution of wild-type native prion protein (PRNP) gene homozygotes among deer sampled. Predation by mountain lions (Puma concolor) may be helping keep CWD in check. Despite stable appearances, prion disease nonetheless impairs adult survival and likely resilience in this deer herd, limiting its potential for growth despite refuge from hunter harvest and favorable habitat and winter conditions.

Tissue Residue Levels of the Tranquilizer Combination of Butorphanol, Azaperone, and Medetomidine, and the Antagonists, Naltrexone, Atipamezole, and Tolazoline, in Black Bears (Ursus americanus) Postimmobilization

The tranquilizer combination of butorphanol, azaperone, and medetomidine (BAM) has shown good efficacy for immobilization of wildlife, including black bears (Ursus americanus). BAM is antagonized with a combination of naltrexone and atipamezole. We immobilized 19 adult captive wild caught black bears and, except for three bears that were euthanized immediately, bears were recovered with naltrexone and atipamezole. Tissue residues (≥0.01 ppm) for the tranquilizers butorphanol, azaperone, and medetomidine were detected in liver and muscle of all three bears euthanized on day 0 postinjection (PI). Azaperone was not detected after 1 d PI. Residue for medetomidine was detected in two bears: in the liver 3 d PI and in the kidney 6 d PI. Butorphanol was reported in three bears: in fat 5 d PI, in kidney 6 d PI, and, surprisingly, in kidney, muscle, and fat 7 d PI. No tissue residues were detected in the three bears euthanized at 8 d PI. Tissue residues for the antagonists, naltrexone and atipamezole, were detected in bears euthanized 2 and 6 d PI, but not in tissues from animals euthanized at 7 or 8 d PI.

EVALUATION OF TWO MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATIONS IN CAPTIVE ROCKY MOUNTAIN ELK (CERVUS ELAPHUS NELSONI)

Alfaxalone has been successfully used intramuscularly (im) combined with medetomidine and azaperone for immobilization of small ungulates. An experimental 40 mg/ml alfaxalone solution (RD0387) was recently formulated for reduced injection volume. The objective of this study was to assess the efficacy and cardiopulmonary effects of high-concentration alfaxalone combined with medetomidine and azaperone for the intramuscular immobilization of captive Rocky Mountain elk (Cervus elaphus nelsoni). Seven adult female elk were used in a crossover design in which they were administered alfaxalone 1 mg/kg, medetomidine 0.05 mg/kg, and azaperone 0.1 mg/kg or alfaxalone 0.5 mg/kg, medetomidine 0.1 mg/kg, and azaperone 0.1 mg/kg im approximately 3 wk apart. Drugs were delivered to each elk in a chute by hand injection. Once recumbent, elk were placed in sternal recumbency for a period of 30 min, during which time level of sedation, response to minor procedures, heart rate, respiratory rate, rectal temperature, oxygen saturation, and direct arterial blood pressures were recorded every 5 min. Arterial blood gases were performed every 15 min. At 30 min, elk were administered atipamezole 0.25 or 0.5 mg/kg im and recovery quality and times were recorded. Statistical comparisons were made by t test, Wilcoxon signed rank test, and repeated measures analysis (significance level P < 0.05). Both drug combinations provided effective immobilization for 30 min, with induction and recovery time and quality similar to other medetomidine-based combinations used in elk. Cardiopulmonary effects included bradycardia, hypertension, and hypoxemia that resolved with oxygen supplementation. The average injection volume in the low-dose alfaxalone combination was approximately 5 ml. These combinations provided deep sedation and the ability to perform minor procedures in captive elk, with acceptable cardiopulmonary parameters as long as supplemental oxygen was provided.

Research with Agricultural Animals and Wildlife

In fiscal year 2016, agricultural animals such as swine, sheep, goats, and cattle represented 10% of the 820 812 animals used in USDA-regulated research. In addition to traditional agricultural animals, research studies using captive wildlife are becoming increasingly important as human and livestock populations encroach upon, and thus expand interactions with, wildlife populations on the landscape. Optimum healthcare of both livestock and captive wildlife in a research setting requires proper husbandry, management, and veterinary care. Regardless of animal species, proper care and management are essential for animal well-being, valid research data, and the health and safety of animal care personnel. Using wildlife in research presents unique challenges as there is generally limited peer-reviewed research on wildlife welfare, husbandry, and nutrition. Animals often become excited during handling or transport, and care must be taken to avoid injury. When severe injuries do occur, differences may exist in methods of euthanasia. Many wildlife species are evolutionarily programmed to conceal signs of illness, making assessment of their condition difficult; moreover, attending veterinarians are often not as experienced in the care of wildlife as they are in the care of traditional laboratory animals or livestock. These differences are further magnified in the context of wildlife field research. The concepts of replace, reduce, and refine are as valid in livestock and wildlife research as in biomedical research, and investigators should work closely with their Institutional Animal Care and Use Committees to ensure humane animal care. The Institutional Animal Care and Use Committee is centrally important in providing guidelines relative to ethical use of animal subjects for research and can serve as a valuable resource for research accountability.

Use of nalbuphine as a substitute for butorphanol in combination with dexmedetomidine and tiletamine/zolazepam: a randomized non-inferiority trial

OBJECTIVES

The goal of this study was to determine whether a drug combination using nalbuphine with dexmedetomidine and tiletamine/zolazepam is non-inferior to one that uses butorphanol.

METHODS

All healthy cats presenting solely for gonadectomy to two trap-neuter-return mobile clinic days were randomly assigned to induction with a combination of tiletamine/zolazepam 3 mg/kg, dexmedetomidine 7.5 µg/kg and either butorphanol or nalbuphine at 0.15 mg/kg. All participants were blinded to the identity of the combinations. The primary endpoint was clinician satisfaction, comprised of the mean of four satisfaction ratings on a 7-point Likert scale (highly dissatisfied through to highly satisfied) recorded for induction, maintenance of anesthesia, surgery and recovery. Exploratory endpoints included each individual score, number of injections, duration of induction, duration of recovery and need for reversal agent. To assess non-inferiority for the primary endpoint and individual scores, the difference and 95% confidence intervals (CIs) of the difference between the mean clinical scores for the nalbuphine and butorphanol-based combinations were calculated and compared with a prespecified non-inferiority margin of 20% (1.4 points).

RESULTS

Seventy-two cats were enrolled, 36 in each group. The mean ± SD composite score for the combination with nalbuphine was 6.06 ± 0.59 (95% CI 5.86-6.25) points, while the combination with butorphanol was 6.22 ± 0.62 (95% CI 6.01-6.43). The difference between mean scores was 0.17 (-0.12 to 0.45), which did not exceed the prespecified boundary of 1.4, establishing the non-inferiority of nalbuphine. No individual clinical score for nalbuphine was inferior to butorphanol, and there were no significant differences for any secondary endpoints.

CONCLUSIONS AND RELEVANCE

The clinical experience of the nalbuphine-based combination was non-inferior to the butorphanol-based combination. Nalbuphine is an effective substitute for butorphanol, providing another option if butorphanol is unavailable due to shortage, controlled status or cost, without requiring a change in anesthetic workflow.

Sedative, analgesic, behavioral and clinical effects of intravenous nalbuphine-xylazine combination in camels (Camelus dromedarius)

This study examined the sedative, analgesic, behavioral, and clinical effects of a combination of xylazine (XY) and nalbuphine-xylazine (NA-XY) in camels. A total of five adult camels were used in a prospective randomized cross-over design with a wash out period of two weeks. Camels were allocated randomly to two treatment groups: the XY group (xylazine, 1.1mL/100 kg IV) and the NA-XY group (xylazine, 1.1mL/100 kg IV and nalbuphine, 1 mg/kg IV). The sedative, analgesic, behavioral, and clinical effects of XY and NA-XY combination were evaluated prior to administration (baseline) and at 5, 15, 30, 45, 60, 75, 90, and 120 minutes post-administration. The results showed that the NA-XY combination accelerates the onset of sedation and analgesia and prolongs the durations of both sedation (p < 0.001) and analgesia (p < 0.01). The behavioral parameters showed higher scores with a NA-XY combination than xylazine alone. Although a XY injection resulted in a significant decline in the heart and respiratory rate, the NA-XY combination group revealed a non-significant change in both clinical parameters compared to the baseline. In conclusion, the use of a NA-XY combination in camels improved the sedative and analgesic onset and duration with an improved outcome in the behavioral scores, as well as in both the heart and respiratory rates compared to XY alone.

Immobilization of American Beaver (Castor canadensis) with Nalbuphine, Medetomidine, and Azaperone

Thirty-two American beavers (Castor canadensis) were immobilized with a mixture of nalbuphine, medetomidine, and azaperone (NalMedA) for tail transmitter placement and health assessments prior to translocation. Inductions and reversals were very smooth, but regardless of the dose administered, which ranged from 0.02 to 0.06 mL/kg, many beavers reacted to mild stimuli such as being lifted out of the cage, drawing blood from the tail, expressing anal glands for sex determination, and turning on isoflurane to deepen anesthesia before placement of tail transmitters. On a scale from 1 to 5, a sedation score of 4 was achieved in 8/32 beavers and a sedation score of 5 in 1/32 of beavers given a mean (SD) dosage of 0.04 (0.01) mL/kg NalMedA, which equated to a mean of 1.09 (0.21) mg/kg nalbuphine, 0.43 (0.09) mg/kg medetomidine, and 0.36 (0.07) mg/kg azaperone. All other animals achieved lower sedation scores. Supplementary isoflurane was needed to deepen anesthesia before tail transmitter placement. Although Nal-MedA appeared to be safe for use in American beavers, the level of sedation achieved was quite variable. Supplementary oxygen is recommended to reduce hypoxemia.

EVALUATION OF CHEMICAL IMMOBILIZATION IN CAPTIVE BLACK BEARS ( URSUS AMERICANUS) RECEIVING A COMBINATION OF NALBUPHINE, MEDETOMIDINE, AND AZAPERONE

To assess potential seasonal differences in responses to immobilization, we sedated eight orphaned yearling black bears ( Ursus americanus) being held for rehabilitation at a wildlife facility in Colorado, US, using a premixed combination of nalbuphine (40 mg/mL), azaperone (10 mg/mL), and medetomidine (10 mg/mL; NalMed-A) in October (autumn) prior to hibernation and again after emergence in May (spring) prior to their release. We dosed all bears at 1 mL NalMed-A per estimated 45 kg body mass (1 mL NalMed-A/45 kg), delivered by intramuscular injection using a pole syringe, to facilitate routine examination and ear tagging. Arterial blood gases were measured to assess oxygenation and acid-base status of bears both pre and post oxygen supplementation. The mean (SE) dose calculated post hoc was 0.9 (0.04) mg nalbuphine/kg, 0.2 (0.01) mg azaperone/kg, and 0.2 (0.01) mg medetomidine/kg. The mean induction time was 8 (1) min for six of the bears in October and 6 (1) min for eight bears in May. The NalMed-A combination provided good sedation in captive yearling black bears in autumn and spring and was effectively antagonized with a combination of naltrexone and atipamezole. Mild hypoxemia (PaO₂: 53.5-54.4 mmHg) was the most significant side effect and was corrected (PaO₂: 68.4-150.1 mmHg) with supplemental oxygen administered at 2-5 L/min for 5 min (point of sampling).

THE EFFICACY OF NALBUPHINE, MEDETOMIDINE, AND AZAPERONE IN IMMOBILIZING AMERICAN BISON (BISON BISON)

We evaluated a combination of nalbuphine, medetomidine, and azaperone (NalMed-A) in 12 American bison ( Bison bison ) during 13 sedation handling events. The mean (SE) dosage was 0.4 (0.02) mg/kg nalbuphine, 0.08 (0.003) mg/kg medetomidine, and 0.08 (0.003) mg/kg azaperone contained in an average delivery volume of 0.8 mL/100 kg. Two animals required a supplemental dose for safe handling (additive dose used in calculating means) and a third animal was not adequately sedated despite a supplemental dose. Bison immobilized with NalMed-A showed good sedation in 12 of 13 handling attempts. Advantages of this drug combination included a relatively low delivery volume, rapid antagonism, and minimal regulatory burden for component drugs. The most consistent disadvantage was hypoxemia, and oxygen supplementation is recommended when using this sedative combination in bison.