Clinical evaluation of alfaxalone as an anaesthetic induction agent in dogs less than 12 weeks of age

Clinical review of the pharmacological and anaesthetic effects of alfaxalone in dogs

This clinical review summarises the pharmacological and anaesthetic properties of alfaxalone in the dog. Available pharmacokinetic-pharmacodynamic data and factors affecting the induction dose have been reported. Furthermore, quality of induction and recovery after alfaxalone administration, the use of alfaxalone for total intravenous anaesthesia, and its effects on the cardio-respiratory system, on laryngeal motion, on intraocular pressure and tear production have been evaluated. Finally, the use of alfaxalone in dogs undergoing caesarean section and the effect of intramuscular alfaxalone administration have been considered.

Differential effects of four intramuscular sedatives on cardiorespiratory stability in juvenile guinea pigs (Cavia porcellus)

BACKGROUND

Non-invasive physiological monitoring can induce stress in laboratory animals. Sedation reduces the level of restraint required, thereby improving the validity of physiological signals measured. However, sedatives may alter physiological equilibrium introducing unintended bias and/or, masking the experimental outcomes of interest. We aimed to investigate the cardiorespiratory effects of four short-acting sedatives in juvenile guinea pigs.

METHOD

12 healthy, 38 (26-46) day-old Dunkin Hartley guinea pigs were included in this blinded, randomised, crossover design study. Animals were sedated by intramuscular injection using pre-established minimum effective doses of either alfaxalone (5 mg/kg), diazepam (5 mg/kg), ketamine (30 mg/kg), or midazolam (2 mg/kg) administered in random order with a minimum washout period of 48 hours between agents. Sedative depth, a composite score comprised of five assessment criteria, was observed every 5-min from dosing until arousal. Physiological monitoring of cardiorespiratory status included measures of heart rate, blood pressure, respiratory rate, and peripheral microvascular perfusion.

RESULTS

Ketamine and alfaxalone were most effective in inducing stable sedation suitable for physiological monitoring, and diazepam less-so. Midazolam was unsuitable due to excessive hypersensitivity. All sedatives significantly increased heart rate above non-sedated control rates (P<0.0001), without altering blood pressure or microvascular perfusion. Alfaxalone and ketamine reduced respiratory rate relative to their control condition (P<0.0001, P = 0.05, respectively), but within normative ranges.

CONCLUSION

Ketamine and alfaxalone are the most effective sedatives for inducing short duration, stable sedation with minimal cardiorespiratory depression in guinea pigs, while diazepam is less-so. However, alfaxalone is the most appropriate sedative for longitudinal studies requiring multiple physiological timepoints.

Scoping review of quality of anesthetic induction and recovery scales used for dogs

OBJECTIVE

To compare, describe and assess the level of validation of all instruments measuring quality of induction and recovery from anesthesia in dogs.

DATABASES USED

A search was performed using the electronic database PubMed to find articles containing an induction quality scale, a recovery quality scale or both in dogs. Articles not directly accessible through PubMed were obtained through the Auburn University Library website and Google Scholar. The phrases 'induction scoring systems dogs', 'recovery scoring systems dogs', 'anesthetic induction score dogs', and 'anesthetic recovery score dogs' were used for searches using the 'best match search' function. The time frame searched was from 1980 to May 2020. The search was conducted from March 2020 to May 2020.

CONCLUSIONS

A thoroughly tested and validated scale for measuring the quality of induction and recovery does not exist in the current veterinary literature. A large disagreement exists between studies on the use of induction and recovery scales, and many have reported inconsistent results with current instruments. It is recommended that an induction and recovery scale intended for wide-scale use be constructed and tested extensively for psychometric validation and reliability.

Anesthetic effect of a mixture of alfaxalone, medetomidine, and butorphanol for inducing surgical anesthesia in ICR, BALB/c, and C57BL/6 mouse strains

The anesthetic effects of alfaxalone combined with medetomidine and butorphanol were investigated for ICR, BALB/c, and C57BL/6 mice. Mice were administered a combination of 0.5 or 0.75 mg/kg medetomidine and 5 mg/kg butorphanol with 30 or 40 mg/kg alfaxalone (0.5MBA30, 0.75MBA30 and 0.75MBA40, respectively). The drug combinations were administered subcutaneously and were compared with a widely used combination of 0.3 mg/kg medetomidine, 4 mg/kg midazolam, and 5 mg/kg butorphanol (MMB). All three MBA combinations achieved surgical anesthesia, although the recovery time was longer with 0.75MBA30 and 0.75MBA40 compared with 0.5MBA30. Furthermore, several mice exhibited a considerable jumping reaction immediately after injection with 0.75MBA30 and 0.75MBA40. Therefore, 0.5MBA30 may be suitable for inducing surgical anesthesia in the mouse strains tested. The anesthetic scores for 0.5MBA30 were improved compared with those of MMB in all three mouse strains; however, the body temperature drop in C57BL/6 mice was greater with 0.5MBA30. Our results show that the alfaxalone combination, 0.5MBA30, should allow surgical operations that are more stable in more strains of mice than MMB, although the combination may cause hypothermia, especially in C57BL/6 mice.

Attitudes of Veterinary Teaching Staff and Exposure of Veterinary Students to Early-Age Desexing, with Review of Current Early-Age Desexing Literature

Simple Summary

A substantial proportion of cats and a smaller proportion of dogs entering animal shelters are juveniles. Cats are prolific breeders and can be pregnant by 4 months of age, although the traditional desexing age in veterinary practice is 6 months for dogs and cats. Understanding what veterinary students across Australia and New Zealand are being taught in regards to early age desexing (EAD) is necessary to determine the reasons why EAD is not utilized in client-owned cats and dogs more frequently. There are no current studies documenting the exposure of new veterinary graduates to EAD, nor the opinions to EAD of the academics teaching these students. Of staff teaching veterinary students in Australia and New Zealand in 2015, a majority (64%) did not advocate EAD in their teaching of students. Only three out of eight universities provided a majority of students with exposure to EAD procedures before graduation, and only two of these allowed most students to perform EAD.

Abstract

Approximately 50% of cats admitted to Australian shelters are kittens, and 26% of dogs are puppies, and, particularly for cats, euthanasia rates are often high. Cats can be pregnant by 4 months of age, yet the traditional desexing age is 5–6 months, and studies in Australasia and Nth America reveal that only a minority of veterinarians routinely perform early age desexing (EAD) of cats or dogs, suggesting they are not graduating with these skills. This study aimed to describe the attitudes of veterinary teaching staff in Australian and New Zealand universities towards EAD, and to determine if these changed from 2008 to 2015. It also aimed to identify students’ practical exposure to EAD. Most (64%) of the 25 participants in 2015 did not advocate EAD in their teaching and, in their personal opinion, only 32% advocated it for cats. Concerns related to EAD cited by staff included anesthetic risk, orthopedic problems, hypoglycemia, and, in female dogs, urinary incontinence. Those who advocated EAD cited benefits of population control, ease of surgery and behavioral benefits. Only three of the eight universities provided a majority of students with an opportunity to gain exposure to EAD procedures before graduation, and in two of these, most students had an opportunity to perform EAD. In conclusion, most veterinary students in Australia and New Zealand are not graduating with the knowledge or skills to perform EAD, and have little opportunity while at university to gain practical exposure. Welfare agencies could partner with universities to enable students to experience EAD.

The minimum infusion rate of alfaxalone during its co-administration with lidocaine at three different doses by constant rate infusion in goats

OBJECTIVE

To determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement in response to standardized stimulation while co-administered with lidocaine at three different doses by constant infusion rate infusion (CRI) in goats.

STUDY DESIGN

Prospective, blinded, randomized crossover, experimental.

ANIMALS

A total of eight healthy goats: four does and four wethers.

METHODS

Anaesthetic induction was with lidocaine at 1 mg kg^-1 [low dose of lidocaine (L-Lid)], 2 mg kg^-1 [moderate dose (M-Lid)] or 4 mg kg^-1 [high dose (H-Lid)] and alfaxalone at 2 mg kg^-1. Anaesthetic maintenance was with alfaxalone initially at 9.6 mg kg^-1 hour^-1 combined with one of three lidocaine treatments: 3 mg kg^-1 hour^-1 (L-Lid), 6 mg kg^-1 hour^-1 (M-Lid) or 12 mg kg^-1 hour^-1 (H-Lid). The MIR of alfaxalone was determined by testing for responses to a stimulation in the form of clamping on a digit with a Vulsellum forceps every 30 minutes during lidocaine CRI. Basic cardiopulmonary parameters were measured.

RESULTS

The alfaxalone MIRs were 8.64 (6.72-10.56), 6.72 (6.72-8.64) and 6.72 (6.72-6.72) mg kg^-1 hour^-1 during L-Lid, M-Lid and H-Lid, respectively, without any significant differences among treatments. Compared to the initial rate of 9.6 mg kg^-1 hour^-1, these reductions in MIR are equivalent to 10, 30 and 30%, respectively. Significant increases in heart rate (HR) and arterial carbon dioxide partial pressure (PaCO₂) and decreases in arterial haemoglobin saturation (SaO₂), arterial oxygen partial pressure (PaO₂) and respiratory frequency (f_R) immediately after induction were observed during all lidocaine treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Lidocaine reduces the alfaxalone MIR by up to 30% with a tendency towards a plateauing in this effect at high CRIs. Immediate oxygen supplementation might be required to prevent hypoxaemia.

The Association of Shelter Veterinarians' 2016 Veterinary Medical Care Guidelines for Spay-Neuter Programs

As community efforts to reduce the overpopulation and euthanasia of unwanted and unowned cats and dogs have increased, many veterinarians have increasingly focused their clinical efforts on the provision of spay-neuter services. Because of the wide range of geographic and demographic needs, a wide variety of spay-neuter programs have been developed to increase delivery of services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, community cat programs, and services provided through private practitioners. In an effort to promote consistent, high-quality care across the broad range of these programs, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. These guidelines consist of recommendations for general patient care and clinical procedures, preoperative care, anesthetic management, surgical procedures, postoperative care, and operations management. They were based on current principles of anesthesiology, critical care medicine, infection control, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs regardless of location, facility, or type of program. The Association of Shelter Veterinarians envisions that these guidelines will be used by the profession to maintain consistent veterinary medical care in all settings where spay-neuter services are provided and to promote these services as a means of reducing sheltering and euthanasia of cats and dogs.

Optimal management of the critically ill: anaesthesia, monitoring, data capture, and point-of-care technological practices in ovine models of critical care

Animal models of critical illness are vital in biomedical research. They provide possibilities for the investigation of pathophysiological processes that may not otherwise be possible in humans. In order to be clinically applicable, the model should simulate the critical care situation realistically, including anaesthesia, monitoring, sampling, utilising appropriate personnel skill mix, and therapeutic interventions. There are limited data documenting the constitution of ideal technologically advanced large animal critical care practices and all the processes of the animal model. In this paper, we describe the procedure of animal preparation, anaesthesia induction and maintenance, physiologic monitoring, data capture, point-of-care technology, and animal aftercare that has been successfully used to study several novel ovine models of critical illness. The relevant investigations are on respiratory failure due to smoke inhalation, transfusion related acute lung injury, endotoxin-induced proteogenomic alterations, haemorrhagic shock, septic shock, brain death, cerebral microcirculation, and artificial heart studies. We have demonstrated the functionality of monitoring practices during anaesthesia required to provide a platform for undertaking systematic investigations in complex ovine models of critical illness.

Maternal and foetal cardiovascular effects of the anaesthetic alfaxalone in 2-hydroxypropyl-β-cyclodextrin in the pregnant ewe

The objective of this study was to determine the pharmacodynamics effects of the anaesthetic alfaxalone in 2-hydroxypropyl-β-cyclodextrin in pregnant sheep after the intravenous injection of a 2 mg/kg weight dose. Six pregnant Ripollesa sheep, weighing 47.1 ± 4.4 kg, were used. Twenty-four hours after instrumentation, sheep were anaesthetized with intravenous alfaxalone in cyclodextrin. Time to standing from anaesthesia was 30.0 ± 10.81 min. Foetal heart rate increased significantly during the first 5 min after alfaxalone administration. Significant differences were observed in maternal diastolic arterial blood pressure between minute 10 and minutes 90, 120, 150, 180, 210, and 240. Significant differences were observed for foetal systolic arterial blood pressure between 5 and 30 min after alfaxalone administration. Significant differences in foetal pH were detected during the entire study period, whereas maternal pH returned to baseline values by 60 min after alfaxalone administration. The present study indicated that alfaxalone in 2-hydroxypropyl-β-cyclodextrin administered as an intravenous bolus at 2 mg/kg body weight produced minimal adverse effects and an uneventful recovery from anaesthesia in pregnant sheep and their foetus.