Alfaxalone versus alfaxalone-dexmedetomidine anaesthesia by immersion in oriental fire-bellied toads (Bombina orientalis)

COMPARISON OF SUBCUTANEOUS ALFAXALONE AND SUBCUTANEOUS ALFAXALONE-DEXMEDETOMIDINE FOR SEDATION IN THE HOUSTON TOAD (ANAXYRUS HOUSTONENSIS)

The Houston toad (Anaxyrus houstonensis), a primarily terrestrial amphibian of south-central Texas, has been listed as federally endangered since 1970. Sedation is an important tool for obtaining diagnostics and providing treatment in this species. This prospective, randomized, and blinded study compared the sedative effects of SC alfaxalone (Protocol A) at approximately 12 mg/kg (median [range] = 12.70 [12.09-13.95] mg/kg] to SC alfaxalone-dexmedetomidine (Protocol AD) at approximately 12 mg/kg (median [range] = 12.68 [12.16-13.56] mg/kg) and 0.1 mg/kg (median [range] = 0.1 [0.07-0.13] mg/kg), respectively, in adult Houston toads (n = 26). Toads from Protocol AD received atipamezole SC at approximately 1 mg/kg (median [range] = 0.96 [0.75-1.25] mg/kg) 45 min postinduction, whereas toads from Protocol A received the equivalent volume of SC sterile saline at the same time point. Heart rate, gular rate, and times to first effect, loss of righting reflex, ability to position for radiographs, loss of nociception, return of righting reflex, and full recovery were recorded. A significantly greater number of toads lost righting reflex, positioned for radiographs, and lost nociception with Protocol AD compared with Protocol A. Additionally, time to return of righting reflex and time to full recovery were significantly longer with Protocol AD than with Protocol A. The protocols did not differ significantly in time to first effect, time to radiographic positioning, or time to loss of nociception. Histologic examination of four toads euthanized during the study revealed acute injection site reactions from all administered drugs, including saline. No clinical adverse reactions were observed. This study demonstrates that the combination of SC alfaxalone and dexmedetomidine results in deeper sedation than SC alfaxalone alone, but also correlates with longer recovery times despite antagonist administration.

Evaluating the Anesthetic and Physiologic Effects of Intramuscular and Intravenous Alfaxalone in Eastern Mud Turtles (Kinosternon subrubrum)

Current sedation protocols for chelonians can pose a challenge to clinicians because of prolonged induction and recovery times, difficulties in gaining venous access, and natural species variation. This study evaluated the sedative and physiologic effects of intramuscular (IM) and intravenous (IV) alfaxalone in six wild-caught adult eastern mud turtles (Kinosternon subrubrum). The turtles received alfaxalone 10 mg/kg IM and IV in a randomized cross-over design. A 10-day washout period occurred between trials. Baseline parameters (heart rate, respiratory rate, temperature, and reflexes) were assessed prior to injection and every 5 min post-injection until recovery. Three venous blood gas samples were also collected and analyzed over the course of each trial (baseline, induction, and recovery). Intravenous alfaxalone resulted in a significantly faster induction (p = 0.016; median: 1.5 min, 25-75%: 1-7.5, minimum-maximum: 1-21) and a shorter total sedation time (p = 0.041; median: 52 min, 25-75%: 34.5-62.5, minimum-maximum: 33-87) when compared with IM alfaxalone (induction, median: 20 min, 25-75%: 15-22.5, minimum-maximum: 15-25; total, median: 70 min, 25-75%: 65-82.5, minimum-maximum: 65-90). Blood gas and physiologic parameters were not significantly different between groups; however, the pH (p = 0.009) and glucose (p = 0.0001) significantly increased, and partial pressure of carbon dioxide (p = 0.024) significantly decreased over time. This study demonstrated that alfaxalone 10 mg/kg IV or IM can be used to provide safe and effective sedation in eastern mud turtles.

Application of Different Doses of Dexmedetomidine Combined with General Anesthesia in Anesthesia of Patients with Traumatic Tibiofibular Fractures and Its Effect on the Incidence of Adverse Reactions

Objective

To explore the application of different doses of dexmedetomidine combined with general anesthesia in patients with traumatic tibiofibular fractures.

Methods

A total of 120 patients with traumatic tibiofibular fractures treated in our hospital (January 2018–January 2021) were selected as the research subjects and equally grouped into group A, group B, group C, and group D according to the dosage of dexmedetomidine. Group B, group C, and group D were pumped with 0.3 μg/kg, 0.5 μg/kg, and 0.8 μg/kg load doses of dexmedetomidine before anesthesia induction, with the same doses for maintenance during surgery. Group A was intravenously pumped with the same amount of normal saline and received tracheal intubation after anesthesia induction, with propofol and remifentanil to maintain general anesthesia during surgery.

Results

No notable differences in general data were observed among the groups (P > 0.05). Ramsay sedation scores of all groups showed a downward trend after drug withdrawal. At 10 min, 30 min, and 60 min, the scores of groups C and D were markedly higher than those of groups A and B (P < 0.05), and the scores were higher in group D than those in group C (P < 0.05). The HR changes at each period were close between groups A and B (P > 0.05). The HRs at T1 and T2 in group C were slightly lower than those in group D (P > 0.05), and the HRs at T1 in groups A and B were remarkably higher than those in groups C and D, and were higher than those at T0 and T2 (P < 0.05). The SBP levels of all groups began to rise at T0, peaked at T1, and decreased to a lower level at T2 than that at T0. Moreover, the SBP levels of groups C and D at T1 and T2 were notably lower compared with groups A and B (P < 0.05). With a lower DBP level in group C than the other three groups at T1, the DBP levels were notably lower in groups C and D than those in groups A and B at T2 (P < 0.05). With no statistical difference in the MAP levels at T0 among the four groups (P > 0.05), the MAP levels in group A at T1 and T2 were obviously higher compared with groups C and D (P < 0.05). The extubation time in group A was notably longer than that that in groups B, C, and D (P < 0.05), with longer extubation time in group B than that in groups C and D (P < 0.05). The orientation recovery time in group D was markedly shorter than that in groups A, B, and C (P < 0.05). The incidence of cognitive dysfunction, chills, and restlessness in groups C and D was notably lower compared with groups A and B (P < 0.05), with a higher incidence of chills, intraoperative hypotension, and delayed awakening in group D than in group C (P < 0.05).

Conclusion

Dexmedetomidine at doses of 0.5 μg/kg and 0.8 μg/kg has a better effect in the maintenance of general anesthesia for patients with traumatic tibiofibular fractures, with faster orientation recovery, better recovery of postoperative cognitive function, and a lower incidence of adverse reactions. Dexmedetomidine at 0.5 μg/kg is recommended in view of the increased risk of excessive sedation, chills, restlessness, and intraoperative hypotension in patients at 0.8 μg/kg.

ISOFLURANE ANESTHESIA IN BUDWING PRAYING MANTISES (PARASPHENDALE AGRIONINA)

Praying mantises have gained increasing popularity as pets and may be anesthetized to allow morphological identification and clinical procedures. The aim of this study was to evaluate the effects and anesthetic-related complications of isoflurane in oxygen in 15 client-owned budwing mantises (Parasphendale agrionina) undergoing photographic identification. Each mantis was placed in a self-constructed anesthetic chamber and exposed to a mixture of approximately 5% isoflurane in oxygen until anesthetic induction was achieved. Time to anesthetic induction, time to recovery from anesthesia, and quality of anesthesia based on scoring of righting reflex, front legs withdrawal, and muscular tone, were evaluated and recorded, as well as the occurrence of undesired effects. In most mantises, immobility, loss of righting reflex, and myorelaxation were achieved within minutes after the beginning of isoflurane exposure and lasted a time sufficient to allow completion of the procedure. However, mantises aged ≥12 mo had longer time to anesthetic induction (4.3 ± 0.6 m), as well as shorter time to recovery (19.0 ± 8.0 m), than mantises aged <12 mo (0.8 ± 0.4 and 30.0 ± 15.0; P < 0.05). Complications were not observed, and all mantises were returned to their owner on the same evening.

Immersion anaesthesia with ethanol in African giant land snails (Acathina fulica)

Giant African land snails (Achatina fulica) are becoming increasingly popular pets and may be anaesthetised to allow diagnostics and surgical procedures. The objective of the present study was to evaluate the anaesthetic effects and anaesthetic-related complications of immersion in 5% ethanol in client-owned African pet land snails, anaesthetised to allow biopsies of the foot for screening of parasites. Variables such as minutes elapsing from immersion to anaesthetic induction and from removal from the bath to return of tentacle withdrawal reflex and recovery from anaesthesia were recorded, as well as the occurrence of adverse effects. Of the 30 snails enrolled, one (3.3%) had a fatal outcome whereas the remaining 29 (96.7%) snails completed the study and recovered from anaesthesia. Time to anaesthetic induction was 25 [25–29] minutes. Recovery was prolonged in one snail, which required 210 minutes to regain normal muscular strength. Time from removal from the ethanol solution to return of tentacle withdrawal reflex was 20 [14–42] minutes. Beside death, other observed adverse effects were production of bubbles (n = 4; 13.3%), and mucus secretion (n = 4; 13.3%). Immersion in 5% ethanol may be regarded as suitable anaesthetic technique for African giant snails for brief and moderately invasive surgical procedures. Nevertheless, recovery from anaesthesia may be prolonged and unpredictable.

Microbial integrity of preservative-free alfaxalone in a multiple-use system for two storage conditions and three handling techniques

OBJECTIVE To evaluate the microbial integrity of preservative-free cyclodextrin-based alfaxalone in a multiple-use system. SAMPLE 22 vials of preservative-free alfaxalone. PROCEDURES 2 storage conditions (room temperature, 22°C; refrigerated temperature, 4°C) and 3 handling techniques (closed system transfer device, nonclosed dispensing pin, and manufacturer-supplied vial stopper) comprised 6 treatment groups (3 replicates/group). An aliquot (0.5 mL) was withdrawn from each vial daily for 14 days. Samples were immediately inoculated into tryptic soy broth and incubated at 36°C for 24 hours; samples were subcultured onto 5% Columbia sheep blood agar and incubated for 48 hours. Isolated colonies were evaluated for identification. RESULTS There was no evidence of microbial contamination of vials stored for 7 days in refrigeration and handled with a protected port (closed system transfer device or nonclosed dispensing pin). CONCLUSIONS AND CLINICAL RELEVANCE The US FDA prohibits the use of alfaxalone beyond 6 hours after the vial stopper is broached (punctured), as mandated for a preservative-free injectable medication. Findings for the study reported here supported the use of alfaxalone for 7 days when refrigerated and handled with a single puncture of the stopper by use of a protected port (closed system transfer device or nonclosed dispensing pin). This would appear to be a practical alternative for an injectable anesthetic. It would minimize drug waste and the subsequent environmental impact for disposal of unused drug and allow standardization of storage and handling protocols for alfaxalone use in veterinary practices across the United States.

Sedative effects of intramuscular alfaxalone in pet guinea pigs (Cavia porcellus)

OBJECTIVE

To evaluate the efficacy and side effects of alfaxalone administered intramuscularly (IM) as a sedative agent in guinea pigs undergoing survey radiographs.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

A total of 30 client-owned guinea pigs.

METHODS

Following baseline assessments, 5 mg kg^-1 alfaxalone was administered IM. Heart rate, arterial haemoglobin oxygen saturation, respiratory rate, rectal body temperature, palpebral reflex, response to toe and ear pinch, righting reflex, posture, jaw tone and reaction to manipulation were assessed before and after sedation at 5-minute intervals. The time elapsed from onset of sedation to return of locomotion and coordinated limb movements, the quality of recovery and the occurrence of undesired effects were observed and recorded.

RESULTS

The mean ± standard deviation onset of sedation was 2.7 ± 0.6 minutes. The physiological variables remained within normal ranges until completion of the procedure. Palpebral reflex and responsiveness to both ear and toe pinch were maintained during sedation. Neither hypoxaemia nor hypothermia was observed. The duration of sedation was 29.3 ± 3.2 minutes. Sedation and recovery were uneventful, and adverse effects were not observed.

CONCLUSIONS AND CLINICAL RELEVANCE

In conclusion, 5 mg kg^-1 of IM alfaxalone represents a valuable sedation protocol for healthy guinea pigs undergoing minor noninvasive procedures. Further trials are required to investigate its cardiovascular effects, clinical usefulness in unhealthy patients and its combined use with analgesics for procedures associated with nociception.