Anaesthesia and Analgesia in reptiles and amphibians: physiological implications

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

Veterinary anaesthesia has developed markedly in the last half century. These advances can now be brought to bear in ‘cold-blooded’ animals, both in practice, and in the field of comparative physiology, where reptiles and amphibians have been long studied due to their eclectic and fascinating cardiovascular and respiratory systems. These two systems both provide the means of administration of anaesthetics, via the blood or inhaled gases, and are themselves profoundly influenced by anaesthesia. The resulting shifting relationships between physiology and anaesthesia are the subject of this thesis.
There are several components of successful anaesthesia, which, depending on the goal of the anaesthetic, can include: loss of consciousness and memory, loss of reflexes (both of the muscles, and the internal regulatory systems) and the dampening of pain. These attributes are explored in amphibians and reptiles throughout the studies included in this thesis. Chapter I reviews current anaesthesia in reptiles and amphibians, from a physiologist’s point of view. Chapter II provides a concise overview of pain and pain relief (analgesia) in non-mammals. Chapter III gives an example of the cross-over between a drug normally used as pain relief – lidocaine – with sedation, due to the circulatory physiology of the frog. Chapter IV discusses the effects of common drugs used to induce anaesthesia (propofol and alfaxalone) on the circulatory and respiratory system of the frog. Chapter V and VI discuss using alfaxalone to induce sedation and anaesthesia in pythons, with effects on their respiratory and cardiovascular system, and profoundly influenced in its action by the circulatory system of snakes. Inhaled anaesthesia is explored in Chapter VII in tortoises, using MRI to virtually dissect the heart to measure blood flow under different conditions, and reports the effect this blood flow change has on the effective dose of gas anaesthesia. The heart of the tortoise is probed further in Chapter VIII where its efficiency of pumping is determined under anaesthesia. The findings of Chapters VII and VIII prompted a theoretical assessment of the effects of reptile physiology on inhaled anaesthesia – presented in Chapter IX. Recovery of physiology from multi-model anaesthesia is explored in Chapters X for Nile crocodiles.
In summary, these data explore the varied effects of different anaesthetics on an organism’s physiology, and the effects of the diverse and uniquely adaptable cardiovascular system of reptiles and amphibians on anaesthetics. We also expose the particular effects of some drugs used as pain killers on the cardiovascular and respiratory systems.
OriginalsprogEngelsk
ForlagAarhus Universitet
Antal sider194
StatusUdgivet - jun. 2019

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