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Objective: To evaluate the effect of water temperature on intramuscular injected alfaxalone anesthesia in carp (Cyprinus carpio). Materials and Methods: Six healthy adult carp (C. carpio) were intramuscularly injected with alfaxalone (2.5, 5.0, or 7.5 mg/kg) at normal water temperature (25°C) and at low water temperature (2.5 mg/kg, 15°C). The respiratory rate, heart rate (HR), and anesthesia depth (AD) were evaluated every 5 min for 30 min after administration and every 1 h after 60 min after injection. Results: The respiratory and HRs did not change significantly upon alfaxalone injection, regardless of dose. However, a dose-dependent increase in AD scores was observed. Furthermore, 2.5 mg/kg alfaxalone injected in 15°C water showed an almost equal anesthetic effect to that of 5.0 mg/kg alfaxalone in 25°C water. Conclusion: Alfaxalone is readily available, and its anesthetic effect in carp was enhanced by lowering water temperature, illustrating the possibility of intramuscular injection of alfaxalone in fish.

We investigated intramuscular administration of alfaxalone (5.3–10.0 mg/kg) as an immobilizing agent in free-ranging small Indian mongooses (Urva auropunctata) on the island of St. Kitts, West Indies. From 5–11 January 2020, we successfully immobilized 10 of 11 mongooses. Alfaxalone provided rapid onset (median = 3 min) of immobilization. Mean duration of immobilization was 16.8 ± 3 min. Mean recovery time was 5.6 ± 1 min. There was no effect of dose administered on induction, anesthesia, or recovery times at the dose range used. We concluded that alfaxalone represents an effective alternative to dissociative agents for the immobilization of free-ranging mongooses. Further studies are necessary to quantify alfaxalone effects on mongoose vital rates and blood parameters.

The aim of this study was to test the intranasal administration of different anaesthetics in piglets less than seven days of age undergoing castration for their suitability for providing good-quality sedation and short induction and recovery time with minimal stress. Azaperone alone at a high (5 mg/kg), medium (3 mg/kg) and low dosage (2 mg/kg) and in two combinations with either alfaxalone or midazolam were applied intramuscularly (i.m.) or intranasally (i.n.) to 120 healthy piglets. Compared to intramuscular application, intranasal application showed longer induction times, shorter recovery times and higher scores for defence and vocalisation. In conclusion, the intranasal protocols did not meet the requirements in all groups and their use can therefore not be recommended. A rapid induction phase and good quality of sedation could not be guaranteed.

This randomized prospective clinical study aimed to compare the hemodynamic effects of propofol and alfaxalone for the induction of anesthesia in dogs. Thirty-one healthy dogs undergoing various procedures in a private referral center were premedicated with intramuscular acepromazine (0.015 mg/kg) and methadone (0.15 mg/kg). They then received 5 mg/kg of propofol over 30 s for induction, followed by a maintenance dose of 25 mg/kg/h (Group P), or 2 mg/kg of alfaxalone over 30 s for induction, followed by a continuous rate infusion of 10 mg/kg/h (Group A). Heart rate (HR), mean arterial pressure (MAP), and the velocity time integral (VTI) of the aortic blood flow using transthoracic echocardiography were measured before anesthetic induction and every 15 s for 180 s. Dogs not adequately anaesthetized for intubation were excluded from the hemodynamic evaluation. Events of hypotension (any MAP value lower than 60 mmHg) were also recorded. Statistical analyses utilized ANOVA for repeated measures, two-way repeated measures ANOVA, paired t-tests, or Wilcoxon signed rank-test as appropriate. Significance was set at p < 0.05. Two dogs in Group P (2/14) and 3 in Group A (3/17) were excluded from the study because the anesthesia plane was too light to allow intubation. Treatment P resulted in a significant decrease in MAP between 45 and 75 s during the induction period, with no significant variation in HR, VTI, and VTI*HR. In treatment A, HR increases between 60 and 105 s, VTI decreases at 150–180 s. Analysis between groups did not show any difference in MAP ( p = 0.12), HR ( p = 0.10), VTI ( p = 0.22) and VTI*HR ( p = 0.74). During induction, hypotension was detected in 3/12 (25%) dogs in Group P and 1/14 (8%) in Group A. In healthy premedicated dogs, propofol and alfaxalone induction produce similar hemodynamic variations. Propofol induction results in a short-term reduction in MAP, whereas alfaxalone induction preserves MAP and cardiac output by significantly increasing heart rate.

Sedation and general anaesthesia of crocodilians pose unique challenges due to their aggressive nature, poikilothermic physiology, and specific anatomical and physiological characteristics, all factors that complicate crocodilian anaesthesia. This review aimed to systematically review the literature regarding sedation and general anaesthesia of crocodilians with focus on efficacy and impact on vital parameters. A systematic literature search was performed according to PRISMA guidelines on May 2, 2023 in the databases Embase, PubMed, Scopus and Web of Science. Publications were excluded based on predefined exclusion criteria, which encompassed non-standard publications and publications unrelated to crocodilians, with fewer than five animals and/or with insufficient data on sedation and general anaesthesia. Five key factors were used to evaluate the strength of evidence: number of included animals, study design, definition of recovery time, blinded assessment of recovery and conflict of interest. Ten publications were included in this systematic review. Drugs used included alpha-2-adrenoceptor agonists, dissociative anaesthetics, benzodiazepines, neuromuscular blocking agents, propofol, alfaxalone, and inhalant gasses. The studies included in total 55 Alligator mississippiensis , 110 Crocodylus porosus , 15 Crocodylus johnstoni , and 15 Crocodylus niloticus . Factors such as temperature, administration route, dose, species, and age influenced protocols for sedation and general anaesthesia of crocodilians. The studies included used five different study designs. Only one study included a control group, done on retrospectively collected data. Blinded recovery assessments and declarations of no conflict of interest were noted in some studies. The use of four distinct recovery definitions posed challenges to comparability in this systematic review. The studies reported that medetomidine provided stable and reversible sedation, although it depressed heart rate. Alfaxalone was less stable outside the optimal temperature range. Intubation and inhalation anaesthesia were effective, and adrenaline reduced the length of the recovery period. Overall, the review provides valuable insights for veterinarians, researchers, and wildlife professionals involved in sedation and general anaesthesia of the crocodilian species, however, the literature is limited, and further research is needed to improve evidence-based medical management.

The objective of our research was to estimate the therapeutic index and assess the interaction of alfaxalone (IP) with ketamine or xylazine (IM) in chicks by using isobolographic analysis. The up-and-down technique was involved to calculate the median effective anesthetic dosages (ED50) of alfaxalone, xylazine, and ketamine given separately or at the same time in young chicks. Then the up-and-down technique was involved to estimate the median lethal dosage (LD50) of alfaxalone (IP) to determine the safety profile. The ED50 of all anesthetics was evaluated isobolographically to assess the type of interaction between alfaxalone and xylazine or alfaxalone and ketamine. The alfaxalone ED50 was 32.88 mg/kg (IP), whereas the LD50 was 102.40 mg/kg (IP). The ED50 values for alfaxalone, ketamine, and xylazine were 32.88, 12.24, and 2.45 mg/kg, respectively. The ED50 values of alfaxalone with ketamine or xylazine (25:25 ED50 values) were: 7.39+2.35, and 8.61+0.63 mg/kg, respectively. ED50 values were decreased when the combinations of alfaxalone/ketamine or alfaxalone/xylazine were administered by 22-21% and 26-25%, respectively. The anesthesia of chicks with alfaxalone is safe, produces a surgical stage of anesthesia, and can be used for minor surgical procedures. The use of alfaxalone with ketamine or xylazine has been shown to have a synergistic effect and these findings may be of clinical relevance in poultry or may be extended to mammals following further clinical trials.

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 (SpO 2 ), 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 (SpO 2  < 90%) was more severe in the KX group when compared to the AX group (SpO 2  > 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.

Formosan serows are an endemic species in Taiwan. Alfaxalone, a γ-aminobutyric acidA agonist, induces or maintains anesthesia in various veterinary species with reported potential adverse effects of respiratory depression and tachycardia. α2-Adrenoceptor agonists exert sedative and muscle relaxation effects, along with substantial cardiovascular adverse effects. Here, we aimed to evaluate the anesthetic effects of alfaxalone combined with xylazine or dexmedetomidine (AX vs. AD, respectively) in Formosan serows. In this randomized, masked study, AX was administered to four serows, and AD was administered to five serows intramuscularly via blow dart. The time and score of induction and recovery were recorded. Post-intubation, isoflurane was administered for maintenance anesthesia. Heart rate (HR), respiratory rate (RR), peripheral saturation of oxygenation (SpO2), rectal temperature (RT), and end-tidal CO2 (EtCO2) were recorded every five to eight minutes. Atipamezole and tolazoline were administered to antagonize dexmedetomidine and xylazine post-procedure, respectively. Both combinations allowed smooth induction and recovery. The AD group exhibited significantly lower HR and SpO2 and significantly higher RT and EtCO2 than the AX group (both p < 0.01). The AD-treated serows exhibited notable muscle rigidity after induction and significant hypoventilation and hypoxemia during the procedure. Although alfaxalone combined with dexmedetomidine or xylazine can produce satisfactory induction and recovery in Formosa serows, notable hypoxemia and hypoventilation are induced by the alfaxalone–dexmedetomidine combination compared to the alfaxalone–xylazine combination.

This study aimed to determine the effects of intramuscular (IM) administration of alfaxalone with or without dexmedetomidine on short electroretinography (ERG), ocular parameters and cardiorespiratory in healthy cats. Eight healthy female spayed cats were treated with three sedation protocols: IM administration of 5 μg/kg dexmedetomidine (DEX), 5 mg/kg alfaxalone (ALF), and 5 μg/kg dexmedetomidine plus 5 mg/kg alfaxalone (DEX + ALF). The washout period after each treatment was 2 weeks. Physiological parameters, time metrics, intraocular pressure (IOP), Schirmer tear test 1 (STT-1) and a short ERG protocol were recorded. For age data, weight data, time metrics and ERG data, one-way ANOVA with Bonferroni posterior comparisons were performed. For physiological parameters, IOP and STT-1 data, two-way repeated measures ANOVA with Bonferroni posterior comparisons were performed. Statistical significance was set at a -value <0.05. IOPs were increased in all three groups compared to baseline and showed no significant differences among three groups at any time point. STT-1 values were decreased significantly during the process. Significant differences were noticed between a-wave amplitude in the dark-adapted response between DEX and ALF, and a-wave amplitude in light-adapted response between ALF and DEX + ALF. This study demonstrates the feasibility of three sedation protocols for short ERG recording in cats. All these treatments resulted in increased IOP values and reduced STT-1 values. But baseline data of ERG was not obtained as a blank control in cats.

Background Alfaxalone is a fast acting intravenous anaesthetic with high therapeutic index. It is an analogue of the naturally-occurring neurosteroid allopregnanolone responsible for maintenance of cognition and neuroprotection by activation of brain pregnane X receptors and consequent increased production of mature brain-derived neurotrophic factor (m-BDNF). Two studies are reported here: an in vitro study investigated whether alfaxalone activates human pregnane X receptors (h-PXR) as effectively as allopregnanolone; and a clinical study that measured postoperative changes in serum m-BDNF and cognition in patients after alfaxalone anaesthesia compared with propofol and sevoflurane. Methods In vitro Activation of h-PXR by allopregnanolone and alfaxalone solutions (206 - 50,000 nM) was measured using human embryonic kidney cells expressing h-PXR hybridised and linked to the firefly luciferase gene. Light emission by luciferase stimulated by each ligand binding with h-PXR was measured. Clinical A double blind prospective randomised study of patients undergoing hip arthroplasty anaesthetised with alfaxalone TIVA ( n  = 8) or propofol TIVA ( n  = 3) or propofol plus sevoflurane inhalational anaesthesia ( n  = 4). The doses of anaesthetics were titrated to the same depth of anaesthesia (BIS 40-60). Subjects’ cognitive performance was assessed using the Grooved Pegboard Test, Digit Symbol Substitution Test (DSST) and Mini Mental State examination (MMSE) for 7 days postoperatively. Serum m-BDNF concentrations were measured for 7 postoperative days. Results In vitro Allopregnanolone and alfaxalone both activated h-PXR, alfaxalone being more efficacious than allopregnanolone: 50,000 nM, p  = 0.0019; 16,700 nM, p  = 0.0472; 5600 nM, p  = 0.0031. Clinical Alfaxalone treated subjects scored better than propofol and sevoflurane anaesthetised patients in the cognition tests: (MMSE p  = 0.0251; Grooved Pegboard test dominant hand pre v post anaesthesia scores p  = 0.8438 for alfaxalone and p  = 0.0156 for propofol and propofol/sevoflurane combined). The higher cognition scores were accompanied by higher serum m-BDNF levels in the alfaxalone anaesthetised patients ( p  < 0.0001). Conclusions These results suggest that sedation and anaesthesia induced by the synthetic neuroactive steroid alfaxalone may be accompanied by effects normally caused by physiological actions of allopregnanolone at PXR, namely, increased secretion of m-BDNF and consequent neuroprotection and preservation of cognition. Trial registration The clinical trial was registered on 17/01/2018 with the Australian New Zealand Clinical Trials Registry: registration number ACTRN12618000064202 [Universal Trial Number U1111-1198-0412].