Effects of isoflurane, sevoflurane and methoxyflurane on the electroencephalogram of the chicken

McIlhone, Amanda E.; Beausoleil, Ngaio J.; Johnson, Craig B.; Mellor, D. J.

doi:10.1111/vaa.12154

Cited by 11 publications

(23 citation statements)

References 29 publications

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“…In chickens, it appears that halothane and methoxyflurane (McIlhone et al . 2014) produce less burst suppression of the EEG at equipotent concentrations than isoflurane or sevoflurane. However, methoxyflurane has known analgesic properties (Lambie 1963; Coffey et al .…”

Section: Discussionmentioning

confidence: 94%

“…2008; McIlhone et al . 2014), although a direct comparison would be required to confirm this. The results of this study, along with previously reported EEG responses to isoflurane, sevoflurane and methoxyflurane in the chicken (Martin‐Jurado et al .…”

Section: Discussionmentioning

confidence: 99%

“…2008; McIlhone et al . 2014), suggest that inhalant anaesthetics have similar actions in both the avian and mammalian brains.…”

Section: Discussionmentioning

confidence: 99%

“…2008; McIlhone et al . 2014). However, to the best of the authors’ knowledge, no previous studies have examined the effects of halothane on the chicken EEG.…”

Section: Introductionmentioning

confidence: 99%

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Effects of halothane on the electroencephalogram of the chicken

McIlhone

Beausoleil

Kells

et al. 2018

Veterinary Medicine & Sci

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Little is known about the effects of inhalant anaesthetics on the avian electroencephalogram (EEG). The effects of halothane on the avian EEG are of interest, as this agent has been widely used to study nociception and analgesia in mammals. The objective of this study was to characterize the effects of halothane anaesthesia on the EEG of the chicken. Twelve female Hyline Brown chickens aged 8–10 weeks were anaesthetized with halothane in oxygen. For each bird, anaesthesia was progressively increased from 1–1.5 to 2 times the Minimum Anesthetic Concentration (MAC), then progressively decreased again. At each concentration, a sample of EEG was recorded after a 10‐min stabilization period. The mean Total Power (PTOT), Median Frequency (F50) and 95% Spectral Edge Frequency (F95) were calculated at each halothane MAC, along with the Burst Suppression Ratio (BSR). Burst suppression was rare and BSR did not differ between halothane concentrations. Increasing halothane concentration from 1 to 2 MAC resulted in a decrease in F50 and increase in PTOT, while F95 increased when MAC was reduced from 1.5 to 1. The results indicate dose‐dependent spectral EEG changes consistent with deepening anaesthesia in response to increasing halothane MAC. As burst suppression was rare, even at 1.5 or 2 times MAC, halothane may be a suitable anaesthetic agent for use in future studies exploring EEG activity in anaesthetized birds.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

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Effects of halothane on the electroencephalogram of the chicken

McIlhone

Beausoleil

Kells

et al. 2018

Veterinary Medicine & Sci

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“…Even the complete loss of opercula movements, considered to be the deepest level of anaesthesia (Table ), occurred in one fish ~40 s before VERs were lost. Time until signal amplitude reduced to <12% pre‐treatment amplitude, considered incompatible with consciousness with calves (Gibson et al, ) and chickens (Mcilhone et al, ), occurred 9.28 ± 1.86 min after submersion, just after ventilation was lost at 9.03 ± 0.46 min.…”

Section: Discussionmentioning

confidence: 99%

Non‐invasive recording of brain function in rainbow trout: Evaluations of the effects of MS‐222 anaesthesia induction

2019

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Effective methods of producing instantaneous and irreversible unconsciousness at the time of slaughter are crucial for ensuring animal welfare in commercial aquaculture. However, the traditional method of visually evaluating unconsciousness has been shown to be insufficient and may lead to misjudgements of stunning efficiency. In this study, we developed a non‐invasive technique that measures brain activity in fish as an alternative to traditional invasive, brain implants and used it to determine when a change in consciousness occurs in trout during anaesthesia induction. Nine rainbow trout (Oncorhynchus mykiss) were equipped with a custom designed silicone cup fitted with electrodes and submerged in 10°C water with dissolved MS‐222. During anaesthesia, the state of consciousness was assessed by recordings of electroencephalogram (EEG). The EEG recordings were analysed both by visually evoked responses from light stimulation (VERs) and from changes in signal amplitude, median frequency and relative signal power. According to the loss of VERs and decrease in signal amplitude, trout transitioned to surgical depth of anaesthesia within 5 min. Our results show that consciousness, or loss of, can be determined using a non‐invasive system to record EEG in fish.

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