Anaesthesia with sevoflurane in pigeons: minimal anaesthetic concentration (MAC) determination and investigation of cardiorespiratory variables at 1 MAC

Abstract

The objective of the study was to determine the minimal anaesthetic concentration (MAC) of sevoflurane (SEVO) in pigeons and investigate the effects of 1 MAC SEVO anaesthesia on cardiovascular and respiratory variables compared with the awake state. This is a prospective, experimental study. Animals were seven healthy adult pigeons. After acclimatisation to handling, heart rate (HR), heart rhythm, respiratory rate (fR), end-expired carbon dioxide tension (PE'CO2), inspired CO2 tension, indirect systolic arterial blood pressure (SAP) and cloacal temperature were measured to determine baseline, 'awake' values. Pigeons were then anaesthetised with SEVO and MAC was determined by the 'bracketing' method. The same variables were monitored during a 40 minute period at 1.0 MAC SEVO for each bird. Mean MAC was 3.0±0.6 per cent for SEVO. During maintenance of anaesthesia at 1.0 MAC, SAP decreased significantly (P<0.001) without any significant change in HR. Although PE'CO2 increased significantly (P=0.001) despite an increase in fR, awake PE'CO2 values were unexpectedly low. Sinus arrhythmias were detected in two birds under SEVO anaesthesia. The times to tracheal intubation and to recovery were 2.5±0.7 and 6.4±1.7 minutes, respectively. Recovery was rapid and uneventful in all birds. In conclusion, SEVO is suitable for anaesthesia in pigeons.

The Determination of the Minimum Anaesthetic Concentration of Halothane in the Rock Dove (Columba livia) Using an Electrical Stimulus

“…Cardiac arrhythmias were observed in all birds during anaesthesia, however, the type of arrhythmia or timing of application of the electrical stimulus meant that the risk of these events impacting MAC measurement was minimised. The second-degree atrioventricular block was regularly observed, similar to reports in isoflurane and sevoflurane anaesthetised Rock Doves [13,14]. One bird also had atrioventricular dissociation, an arrhythmia not previously reported in Rock Doves.…”

“…The variation of MAC values attributed to species is typically quoted as 10-20%, with between-species variation less at around 10% [12]. This has not been maintained in previous pigeon studies where considerably more variability in both individual and group MAC values have been reported [13,14,18]. The present study further challenges this concept, with both intra-and interspecies variation much higher than reported.…”

“…Seven adult Rock Doves (Columbia livia) of undetermined sex, weighing 341 ± 34 g, were included in the study. The number of animals chosen was due to previous pigeon MAC studies using the same number and the bracket method being accurate in small sample sizes [12][13][14]. The birds were obtained during a pest population cull in Wellington, New Zealand and transported the same day to the housing at Massey University Veterinary Tower by ventilated private vehicle with visual assessment each 30 min.…”

Effects of alfaxalone on induction quality of inhalation anesthesia in domestic pigeons (<i>Columba livia domestica</i>)

“…Postinduction apnea following the administration of alfaxalone, as well as agitation and ataxia during the recovery process, have been reported as side effects in mute swans [ 1 ]. In this study, after IM administration of alfaxalone, HR and RR in the alfaxalone group were significantly lower compared with baseline ( Table 2 ), but values were similar to those of HR and RR in awake state pigeons in other studies (155 ± 28, 170 ± 24 beats/min, and 34 ± 6, 32 ± 5 breath/min, respectively) [ 2 , 3 ]. There was no significant difference in CT, SAP, DAP, and MAP.…”

“…However, in contrast to other avian species, studies on anesthesia in pigeons have been limited. Although studies have been conducted separately on injection [ 13 , 22 ] and inhalation [ 2 , 3 , 6 ] anesthesia, the use of alfaxalone as a premedication prior to inhalant anesthesia for pigeons has not been evaluated.…”