Original Research

Long-term surgical anaesthesia with isoflurane in human habituated Nile Crocodiles

George F. Stegmann, Catherine J.A. Williams, Craig Franklin, Tobias Wang, Michael Axelsson
Journal of the South African Veterinary Association | Vol 88 | a1451 | DOI: https://doi.org/10.4102/jsava.v88i0.1451 | © 2017 George F. Stegmann, Catherine J.A. Williams, Craig Franklin, Tobias Wang, Michael Axelsson | This work is licensed under CC Attribution 4.0
Submitted: 28 June 2016 | Published: 24 February 2017

About the author(s)

George F. Stegmann, Department of Companion Animal Clinical Studies, University of Pretoria, South Africa
Catherine J.A. Williams, Department of Bioscience, Aarhus University, Denmark
Craig Franklin, School of Biological Sciences, University of Queensland, Australia
Tobias Wang, Department of Bioscience, Aarhus University, Denmark
Michael Axelsson, Department of Biological and Environmental Sciences, University of Gothenburg, Sweden

Abstract

A suitable long-term anaesthetic technique was required for implantation of physiological sensors and telemetric devices in sub-adult Nile crocodiles (Crocodylus niloticus) to allow the collection of physiological data. Five Nile crocodiles with a median body mass of 24 kg were used. After manual capture, they were blindfolded and 0.2 mL (1 mg/mL) medetomidine was administered intramuscularly in four of the animals which had an estimated body mass between 20 kg and 30 kg. One crocodile with an estimated body mass of 50 kg received 0.5 mL. For induction, 5 mL propofol (10 mg/mL) was injected intravenously into the occipital sinus. Additional doses were given when required to ensure adequate anaesthesia. Anaesthesia was maintained with 1.5% isoflurane. Ventilation was controlled. Local anaesthesia was administered for surgical incision and external placement of the radio transmitter. Medetomidine was antagonised with atipamezole at the end of surgery. Median heart rate during surgery was 22 beats/min, at extubation 32 beats per min and 30 beats per min the following day at the same body temperature as under anaesthesia. Median body temperature of the animals increased from 27.3 °C to 27.9 °C during anaesthesia, as room temperature increased from 24.5 °C to 29.0 °C during surgery. Anaesthesia was successfully induced with intramuscular medetomidine and intravenous propofol and was maintained with isoflurane for the placement of telemetric implants. Intraoperative analgesia was supplemented with lidocaine infiltration. Perioperative physiological parameters remained stable and within acceptable clinical limits. Multiple factors appear to influence these variables during the recovery period, including residual anaesthetic effects, environmental temperature and physical activity.

 


Keywords

Nile crocodile; crocodylus niloticus; lidocaine; anaesthesia; medetomidine; propofol; isoflurane

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