Paolo Monticelli1, Hayley L Ronaldson1, John R Hutchinson2, Andrew R Cuff2, Dario d'Ovidio3, Chiara Adami4. 1. Department of Clinical Sciences and Services, The Royal Veterinary College, Hatfield, UK. 2. Department of Genetics, Evolution and Environment, University College London, London, UK; Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, UK. 3. Veterinari Esotici Campani, Clinica Veterinaria VETLAN, Battipaglia, SA, Italy. 4. Department of Clinical Sciences and Services, The Royal Veterinary College, Hatfield, UK. Electronic address: cadami@rvc.ac.uk.
Abstract
OBJECTIVE: To describe the anaesthetic, physiological and side effects of intramuscular (IM) medetomidine and ketamine, followed by inhalational anaesthesia with sevoflurane, in Nile crocodiles (Crocodylus niloticus). STUDY DESIGN: Observational trial. ANIMALS: Ten juvenile captive-bred Nile crocodiles undergoing surgical implantation of skeletal beads and muscular electrodes. METHODS: During preanaesthetic examination, the following variables were assessed: heart (HR) and respiratory (fR) rates, and response to palpebral, corneal and toe- and tail-pinch withdrawal reflexes. The crocodiles were injected IM with an initial combination of medetomidine and ketamine and re-evaluated at 5 minute intervals for 20 minutes, or until they appeared unresponsive. If that did not occur, the drugs were redosed according to a decision tree based on the observed effects. The righting, biting and palatal valve reflexes were assessed in the unresponsive crocodiles, and used to confirm anaesthetic induction. Anaesthesia was maintained with sevoflurane in oxygen. At the end of surgery, medetomidine was antagonized with IM atipamezole. RESULTS: The decision tree identified 0.3 mg kg-1 medetomidine and 15 mg kg-1 ketamine as a useful drug combination, which resulted in anaesthetic induction and surgical anaesthesia 16 ± 8 and 16 (25-20) minutes after injection, respectively. Compared to baseline, HR and fR significantly decreased after anaesthetic induction (p < 0.001), but then remained stable throughout surgery. Intraoperatively, cloacal temperature [27 (26-30) °C] did not change over time (p = 0.48). The total dose of atipamezole was 2 (1-3) mg kg-1 and time to recovery was 36 (20-60) minutes. Perioperative complications were not observed. CONCLUSIONS: and clinical relevance Medetomidine and ketamine, injected IM and followed by sevoflurane anaesthesia, may be regarded as a useful anaesthetic technique for juvenile Nile crocodiles undergoing minimally invasive experimental surgery.
OBJECTIVE: To describe the anaesthetic, physiological and side effects of intramuscular (IM) medetomidine and ketamine, followed by inhalational anaesthesia with sevoflurane, in Nile crocodiles (Crocodylus niloticus). STUDY DESIGN: Observational trial. ANIMALS: Ten juvenile captive-bred Nile crocodiles undergoing surgical implantation of skeletal beads and muscular electrodes. METHODS: During preanaesthetic examination, the following variables were assessed: heart (HR) and respiratory (fR) rates, and response to palpebral, corneal and toe- and tail-pinch withdrawal reflexes. The crocodiles were injected IM with an initial combination of medetomidine and ketamine and re-evaluated at 5 minute intervals for 20 minutes, or until they appeared unresponsive. If that did not occur, the drugs were redosed according to a decision tree based on the observed effects. The righting, biting and palatal valve reflexes were assessed in the unresponsive crocodiles, and used to confirm anaesthetic induction. Anaesthesia was maintained with sevoflurane in oxygen. At the end of surgery, medetomidine was antagonized with IM atipamezole. RESULTS: The decision tree identified 0.3 mg kg-1 medetomidine and 15 mg kg-1 ketamine as a useful drug combination, which resulted in anaesthetic induction and surgical anaesthesia 16 ± 8 and 16 (25-20) minutes after injection, respectively. Compared to baseline, HR and fR significantly decreased after anaesthetic induction (p < 0.001), but then remained stable throughout surgery. Intraoperatively, cloacal temperature [27 (26-30) °C] did not change over time (p = 0.48). The total dose of atipamezole was 2 (1-3) mg kg-1 and time to recovery was 36 (20-60) minutes. Perioperative complications were not observed. CONCLUSIONS: and clinical relevance Medetomidine and ketamine, injected IM and followed by sevoflurane anaesthesia, may be regarded as a useful anaesthetic technique for juvenile Nile crocodiles undergoing minimally invasive experimental surgery.
Authors: Ashleigh L A Wiseman; Peter J Bishop; Oliver E Demuth; Andrew R Cuff; Krijn B Michel; John R Hutchinson Journal: J Anat Date: 2021-03-23 Impact factor: 2.610