COMPARISON OF THE EFFICACY AND SAFETY OF MEDETOMIDINE-KETAMINE VERSUS MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATION IN FREE-RANGING ROCKY MOUNTAIN BIGHORN SHEEP ( OVIS CANADENSIS )

Comparison of anesthetic effects of xylazine combined with alfaxalone or ketamine and maintained with isoflurane in captive Formosan Reeve's Muntjac (Muntiacus reevesi micrurus)

Formosan Reeve's muntjac is a Cervidae species endemic to Southeast China and Taiwan. However, research on different anesthetic protocols, their effects, and their safety in Formosan Reeve's muntjac is limited. This study evaluated the effects of ketamine-xylazine (KX) and alfaxalone-xylazine (AX) administered via blow darts to nine muntjacs. Induction and recovery times as well as the quality were assessed by a blinded observer. Peripheral oxygen saturation (SpO2), heart rate, respiratory rate, and rectal temperature were recorded for at least 30 min. Tolazoline (4 mg/kg) was used post-procedure to reverse xylazine's effects. The mean doses were 4.68 ± 2.18 mg/kg for ketamine and 3.22 ± 1.33 mg/kg for xylazine in the KX group. In the AX group, the mean doses were 4.38 ± 0.31 mg/kg for alfaxalone and 1.19 ± 0.26 mg/kg for xylazine. The median induction times were 339.5 s (range 180.0-375.0) for KX and 125.0 s (range 71.0-334.0) for AX, with both groups scoring 3.0 for induction quality. The recovery times were 507.5 s (range 266.0-1081.0) for KX and 243.0 s (range 92.0-480.0) for AX, with recovery scores of 2.3 and 3.0, respectively, showing no significant difference. Hypoxemia (SpO2 < 90%) was more severe in the KX group when compared to the AX group (SpO2 > 92%), and rectal temperatures were higher in the former during the first 15 min. Heart and respiratory rates showed no significant differences between groups. Our findings demonstrate that both anesthetic combinations achieve reliable induction and satisfactory recovery in Formosan Reeve's muntjac, with the ketamine-xylazine combination causing a more profound hypoxemia post-induction compared to the alfaxalone-xylazine combination.

Neuroprotective Potential of Origanum majorana L. Essential Oil Against Scopolamine-Induced Memory Deficits and Oxidative Stress in a Zebrafish Model

Origanum majorana L., also known as sweet marjoram, is a plant with multiple uses, both in the culinary field and traditional medicine, because of its major antioxidant, anti-inflammatory, antimicrobial, and digestive properties. In this research, we focused on the effects of O. majorana essential oil (OmEO, at concentrations of 25, 150, and 300 μL/L), evaluating chemical structure as well as its impact on cognitive performance and oxidative stress, in both naive zebrafish (Danio rerio), as well as in a scopolamine-induced amnesic model (SCOP, 100 μM). The fish behavior was analyzed in a novel tank-diving test (NTT), a Y-maze test, and a novel object recognition (NOR) test. We also investigated acetylcholinesterase (AChE) activity and the brain's oxidative stress status. In parallel, we performed in silico predictions (research conducted using computational models) of the pharmacokinetic properties of the main compounds identified in OmEO, using platforms such as SwissADME, pKCSM, ADMETlab 2.0, and ProTox-II. The results revealed that the major compounds were trans-sabinene hydrate (36.11%), terpinen-4-ol (17.97%), linalyl acetate (9.18%), caryophyllene oxide (8.25%), and α-terpineol (6.17%). OmEO can enhance memory through AChE inhibition, reduce SCOP-induced anxiety by increasing the time spent in the top zone in the NTT, and significantly reduce oxidative stress markers. These findings underscore the potential of using O. majorana to improve memory impairment and reduce oxidative stress associated with cognitive disorders, including Alzheimer's disease (AD).

The utility of a novel formulation of alfaxalone in a remote delivery system

OBJECTIVE

To quantify induction time, reliability, physiological effects, recovery quality and dart volume of a novel formulation of alfaxalone (40 mg mL^-1) used in combination with medetomidine and azaperone for the capture and handling of wild bighorn sheep.

STUDY DESIGN

Prospective clinical study.

ANIMALS

A total of 23 wild bighorn sheep (Ovis canadensis) in Sheep River Provincial Park, AB, Canada.

METHODS

Free-ranging bighorn sheep were immobilized using medetomidine, azaperone and alfaxalone delivered with a remote delivery system. Arterial blood was collected for measurement of blood gases, physiologic variables (temperature, heart and respiratory rates) were recorded and induction and recovery length and quality were scored.

RESULTS

Data from 20 animals were included. Administered dose rates were alfaxalone (0.99 ± 0.20 mg kg^-1; 40 mg mL^-1), azaperone (0.2 ± 0.04 mg kg^-1; 10 mg mL^-1) and medetomidine (0.16 ± 0.03 mg kg^-1; 30 mg mL^-1). The mean drug volume injected was 1.51 mL. The median (range) induction time was 7.7 (5.8-9.7) minutes, and recovery was qualitatively smooth.

CONCLUSIONS AND CLINICAL RELEVANCE

An increased concentration formulation of alfaxalone was administered in combination with medetomidine and azaperone, and resulted in appropriate anesthesia for the capture and handling of bighorn sheep. The dart volume was small, with potential for reducing capture-related morbidity.

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.

Evaluation of intramuscular sodium nitroprusside injection to improve oxygenation in white-tailed deer (Odocoileus virginianus) anesthetized with medetomidine-alfaxalone-azaperone

OBJECTIVE

In ungulates, α₂-adrenergic agonists can decrease oxygenation possibly through alteration of pulmonary perfusion. Sodium nitroprusside can decrease pulmonary vascular resistance (PVR) and increase cardiac output (Q˙_t) through vasodilation. The objective was to determine if sodium nitroprusside would improve pulmonary perfusion and attenuate the increased alveolar-arterial (a-a) gradient resulting from medetomidine-azaperone-alfaxalone (MAA) administration.

STUDY DESIGN

Prospective, randomized, crossover study with a 2 week rest period.

ANIMALS

A group of eight adult female captive white-tailed deer (Odocoileus virginianus).

METHODS

Deer were administered MAA intramuscularly (IM), and auricular artery and pulmonary artery balloon catheters were placed. Deer spontaneously breathed air. Saline or sodium nitroprusside (0.07 mg kg^-1) were administered IM 40 minutes after MAA injection. Heart rate (HR), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), pulmonary artery occlusion pressure (PAOP), right atrial pressure (RAP), Q˙_t, arterial pH, PaCO₂ and PaO₂ were obtained immediately before nitroprusside injection (baseline) and 5, 10 and 15 minutes afterwards. Mixed venous blood samples were obtained at baseline and at 5 minutes. Systemic vascular resistance (SVR), PVR, intrapulmonary shunt fraction (Q˙_s/Q˙_t), a-a gradient, oxygen delivery (D˙O₂) and oxygen extraction ratio (O₂ER) were calculated. Statistical analysis was performed with repeated measures analysis of variance with correction factors. A p value < 0.05 was considered significant.

RESULTS

With nitroprusside, MAP, MPAP, PAOP, RAP, SVR and O₂ER significantly decreased and HR, Q˙_t and D˙O₂ increased compared with baseline and between treatments. There was a significant decrease in PVR and a-a gradient and increase in PaO₂ compared with baseline and saline treatment. Changes were not sustained.

CONCLUSIONS AND CLINICAL RELEVANCE

Nitroprusside temporarily changed hemodynamic variables, increased PaO₂ and decreased a-a gradient. Nitroprusside possibly led to better pulmonary perfusion of ventilated alveoli. However, IM nitroprusside at this dose is not recommended because of severe systemic hypotension and short action.

Cardiovascular effects of intravenous vatinoxan (MK-467) in medetomidine-tiletamine-zolazepam anaesthetised red deer (Cervus elaphus)

OBJECTIVE

To determine the effect of intravenous vatinoxan administration on bradycardia, hypertension and level of anaesthesia induced by medetomidine-tiletamine-zolazepam in red deer (Cervus elaphus).

STUDY DESIGN AND ANIMALS

A total of 10 healthy red deer were included in a randomised, controlled, experimental, crossover study.

METHODS

Deer were administered a combination of 0.1 mg kg^-1 medetomidine hydrochloride and 2.5 mg kg^-1 tiletamine-zolazepam intramuscularly, followed by 0.1 mg kg^-1 vatinoxan hydrochloride or equivalent volume of saline intravenously (IV) 35 minutes after anaesthetic induction. Heart rate (HR), mean arterial blood pressure (MAP), respiration rate (f_R), end-tidal CO₂ (Pe'CO₂), arterial oxygen saturation (SpO₂), rectal temperature (RT) and level of anaesthesia were assessed before saline/vatinoxan administration (baseline) and at intervals for 25 minutes thereafter. Differences within treatments (change from baseline) and between treatments were analysed with linear mixed effect models (p < 0.05).

RESULTS

Maximal (81 ± 10 beats minute^-1) HR occurred 90 seconds after vatinoxan injection and remained significantly above baseline (42 ± 4 beats minute^-1) for 15 minutes. MAP significantly decreased from baseline (122 ± 10 mmHg) to a minimum MAP of 83 ± 6 mmHg 60 seconds after vatinoxan and remained below baseline until end of anaesthesia. HR remained unchanged from baseline (43 ± 5 beats minute^-1) with the saline treatment, whereas MAP decreased significantly (112 ± 16 mmHg) from baseline after 20 minutes. Pe'CO₂, f_R and SpO₂ showed no significant differences between treatments, whereas RT decreased significantly 25 minutes after vatinoxan. Level of anaesthesia was not significantly influenced by vatinoxan.

CONCLUSIONS AND CLINICAL RELEVANCE

Vatinoxan reversed hypertension and bradycardia induced by medetomidine without causing hypotension or affecting the level of anaesthesia in red deer. However, the effect on HR subsided 15 minutes after vatinoxan IV administration. Vatinoxan has the potential to reduce anaesthetic side effects in non-domestic ruminants immobilised with medetomidine-tiletamine-zolazepam.

Etorphine-Azaperone Immobilisation for Translocation of Free-Ranging Masai Giraffes (Giraffa Camelopardalis Tippelskirchi): A Pilot Study

Simple Summary

Due to their peculiar anatomy and sensitivity to drugs, giraffes are among the most challenging mammals to immobilise. Masai giraffes have recently been listed as endangered. Hence, their conservation needs actions that require veterinary capture such as translocations. In this study, we evaluated a new protocol of immobilisation for translocation of free-ranging Masai giraffes. The hypothesis is that, by combining a potent opioid with a tranquiliser, it is possible to mitigate the capture stress, which is a major cause of disastrous homeostatic consequences, including capture myopathy and death. The combination produced, in all individuals, smooth and quick inductions and reliable immobilisations. Although hypoxaemia in a few individuals and acidosis were seen, the overall cardiorespiratory function was adequate. Whereas the initial stress to the capture was limited in the individuals, likely due to tourism-related habituation, the opioid-related excitement and resulting increased exertion was responsible for worse immobilisation and physiological derangement. A low dose of an antagonist was used and evaluated and, in the two-week boma follow-up, it proved to be efficient in providing safe recoveries and transport. At the investigated doses, the combination provided partially reversed immobilisation that allowed uneventful translocation in free-ranging Masai giraffes.

Abstract

Etorphine-azaperone immobilisation was evaluated for translocation of Masai giraffes. Nine giraffes were darted with 0.012 ± 0.001 mg/kg etorphine and 0.07 ± 0.01 mg/kg azaperone. Once ataxic, giraffes were roped for recumbency and restrained manually. Naltrexone (3 mg/mg etorphine) was immediately given intravenously to reverse etorphine-related side effects. Protocol evaluation included physiological monitoring, blood-gas analyses, anaesthetic times, and quality scores (1 = excellent, 4 = poor). Sedation onset and recumbency were achieved in 2.6 ± 0.8 and 5.6 ± 1.4 min. Cardio-respiratory function (HR = 70 ± 16, RR = 32 ± 8, MAP = 132 ± 16) and temperature (37.8 ± 0.5) were stable. Arterial gas analysis showed hypoxaemia in some individuals (PaO₂ = 67 ± 8 mmHg) and metabolic acidosis (pH = 7.23 ± 0.05, PaCO₂ = 34 ± 4 mmHg, HCO₃⁻ = 12.9 ± 1.2 mmol/l). Minor startle response occurred, while higher induction-induced excitement correlated to longer inductions, worse restraint, and decreased HCO₃⁻. After 19 ± 3.5 min of restraint, giraffes were allowed to stand and were loaded onto a chariot. Immobilisations were good and scored 2 (1–3). Inductions and recoveries were smooth and scored 1 (1–2). Translocations were uneventful and no complications occurred in 14-days boma follow-up.