The effects on cardio-respiratory and acid–base variables of a constant rate infusion of alfaxalone–HPCD in sheep

Comparison of alfaxalone-medetomidine and tiletamine-zolazepam in rescued common palm civets (Paradoxurus musangus)

Forty rescued common palm civets were anesthetized. Twenty animals received intramuscular injections of alfaxalone 5 mg/kg and medetomidine 0.05 mg/kg (A-M group), whereas twenty animals received 5 mg/kg of tiletamine and zolazepam (T-Z group). The A-M group was reversed with atipamazole 0.25 mg/kg. There were no significant differences in the time from anesthetic injection to induction and intubation between the A-M and T-Z groups. The time from the injection of reversal in the A-M group and the time from cessation of isoflurane in the T-Z group to extubation, first response to recovery and ambulation were longer (P<0.05) in the T-Z group. The T-Z group recorded lower (P<0.05) rectal temperatures compared to the A-M group. This study showed that both drug combinations can be used effectively for the immobilization of civets. The A-M combination provided better anesthetic depth, but with higher incidence of bradycardia and hypoxemia. The recovery time was reduced significantly as atipamezole was used as a reversal agent in the A-M combination.

Cardiopulmonary Effects of a Partial Intravenous Anesthesia Technique for Laboratory Swine

Various anesthetic protocols are used in laboratory swine, each with specific advantages and disadvantages. Partial intravenous anesthetic techniques (PIVA) help minimize dose-dependent cardiopulmonary effects of inhalant drugs. The aim of this study was to determine the cardiopulmonary effects of a PIVA in laboratory swine. In a prospective, nonrandomized clinical study, 8 healthy juvenile Landrace-White pigs were premedicated with azaperone (0.20 ± 0.20 mg/kg IM), dexmedetomidine (0.02 ± 0.002 mg/kg IM), and alfaxalone (2.0 ± 0.20 mg/kg IM), and anesthesia was induced with intravenous alfaxalone. Anesthesia was maintained by using constant-rate infusion of dexmedetomidine (2 μg/kg/h) and alfaxalone (25 μg/kg/min) in combination with isoflurane. After the fraction of expired isoflurane was adjusted to 1.1% to 1.5%, respiratory rate, heart rate, systemic and pulmonary arterial pressure, central venous pressure, cardiac output, bispectral index, systemic vascular resistance, and arterial and mixed venous blood gases were recorded every 10 min for 60 min. Statistical analysis consisted of repeated-measures one-way ANOVA. Significant decreases occurred in heart rate, pulmonary mean arterial pressure, pulmonary diastolic pressure, partial pressure of arterial oxygen, partial pressure of venous oxygen; significant increases occurred in respiratory rate, minute volume index, diastolic arterial blood pressure, systemic vascular resistance, and arterial pH over time. We consider that the observed statistically significant cardiopulmonary changes were clinically important and that the PIVA protocol provided hemodynamic and respiratory stability for short-term anesthesia of laboratory swine.

Alfaxalone for maintenance of anaesthesia in ponies undergoing field castration: continuous infusion compared with intravenous boluses

OBJECTIVE

To compare alfaxalone as continuous intravenous (IV) infusion with intermittent IV injections for maintenance of anaesthesia in ponies undergoing castration.

STUDY DESIGN

Prospective, randomized, 'blinded' clinical study.

ANIMALS

A group of 33 entire male Welsh ponies undergoing field castration.

METHODS

After preanaesthetic medication with IV detomidine (10 μg kg^-1) and butorphanol (0.05 mg kg^-1), anaesthesia was induced with IV diazepam (0.05 mg kg^-1) followed by alfaxalone (1 mg kg^-1). After random allocation, anaesthesia was maintained with either IV alfaxalone 2 mg kg^-1 hour^-1 (group A; n = 16) or saline administered at equal volume (group S; n = 17). When necessary, additional alfaxalone (0.2 mg kg^-1) was administered IV. Ponies were breathing room air. Using simple descriptive scales, surgical conditions and anaesthesia recovery were scored. Total amount of alfaxalone, ponies requiring additional alfaxalone and time to administration, time from induction to end of infusion and end of infusion to standing were noted. Indirect arterial blood pressure, pulse and respiratory rates, end-expiratory carbon dioxide partial pressure and arterial haemoglobin oxygen saturation were recorded every 5 minutes. Data were analysed using Student t, Mann-Whitney U and chi-square tests, where appropriate (p < 0.05).

RESULTS

Total amount of alfaxalone administered after induction of anaesthesia (0.75 ± 0.27 versus 0.17 ± 0.23 mg kg^-1; p < 0.0001) and time to standing (14.8 ± 4 versus 11.6 ± 4 minutes; p = 0.044) were higher in group A compared to group S. Ponies requiring additional alfaxalone boluses [four (group A) versus seven (group S)] and other measured variables were similar between groups; five ponies required oxygen supplementation [three (group A) versus two (group S)].

CONCLUSION AND CLINICAL RELEVANCE

Continuous IV infusion and intermittent administration of alfaxalone provided similar anaesthesia quality and surgical conditions in ponies undergoing field castration. Less alfaxalone is required when used intermittently.

CAPTURE OF FREE-RANGING MULE DEER (ODOCOILEUS HEMIONUS) WITH A COMBINATION OF MEDETOMIDINE, AZAPERONE, AND ALFAXALONE

The combination of medetomidine, azaperone, and alfaxalone has been successfully used to anesthetize captive white-tailed deer ( Odocoileus virginianus ). This same combination was utilized to immobilize free-ranging female mule deer ( Odocoileus hemionus ; MD) in urban and nonurban environments (14 urban MD, 14 nonurban MD) in British Columbia, Canada. Physiologic data were collected to assess the safety and reliability of this drug combination under field conditions. Each deer received estimated dosages of 0.15 mg/kg medetomidine, 0.2 mg/kg azaperone, and 0.5 mg/kg alfaxalone intramuscularly via a remote darting system. Inductions were calm and rapid (mean time to sternal recumbency: urban MD, 6.4±2.2 min; nonurban MD, 8.2±4.1 min). Supplemental drugs were required to induce lateral recumbency in five deer, four of which had experienced initial dart failure (mean time to lateral recumbency: urban MD, 8.5±3.8 min; nonurban MD, 18.7±16.5 min). Recoveries were smooth and uneventful (time to standing: urban MD, 12.5±3.4 min; nonurban MD, 9.0±3.5 min) for all but one debilitated nonurban MD that died shortly after atipamezole administration (at five times the medetomidine dose). The major side effects of the combination were hypoxemia and hypercapnia. The combination of medetomidine, azaperone, and alfaxalone proved suitable for the immobilization of urban and nonurban free-ranging MD.