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Cardiorespiratory, anaesthetic and recovery effects of morphine combined with medetomidine and alfaxalone in rabbits
Author(s) -
NavarreteCalvo R.,
GómezVillamandos R. J.,
Morgaz J.,
Manuel Domínguez J.,
FernándezSarmiento A.,
MuñozRascón P.,
López Villalba I.,
Del Mar Granados M.
Publication year - 2014
Publication title -
veterinary record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.261
H-Index - 99
eISSN - 2042-7670
pISSN - 0042-4900
DOI - 10.1136/vr.101293
Subject(s) - medetomidine , anesthesia , medicine , premedication , morphine , cardiorespiratory fitness , ventilation (architecture) , heart rate , blood pressure , engineering , mechanical engineering
Ten New Zealand White rabbits were used in a crossover experimental study: 200 µg/kg medetomidine and 1 (M1) or 2 mg/kg (M2) morphine were administered intramuscularly. After preoxygenation, anaesthesia was induced with alfaxalone at 10 mg/kg intravenously. The trachea was intubated and 60 per cent oxygen provided. Heart and respiratory rates (HR and RR), direct arterial pressures (APs), arterial pH (pHa), PaO 2 , PaCO 2 and SaO 2 were taken at baseline, after premedication and every 10 minutes during the 90 minutes following induction. The times to return the ear pinch, toe pinch and righting reflexes were recorded. Data were analysed using a two‐way analysis of variance and a paired samples t test. Compared to baseline values, HR, RR, APs, PaO 2 and SaO 2 decreased significantly after premedication in both groups. Postinduction apnoea of 20±10 with M1 and 27±18 minutes with M2 was experienced following alfaxalone administration, intermitent positive pressure ventilation was applied until spontaneous breathing efforts appeared. Cardiovascular variables, RR and pHa remained below, and PaCO 2 over baseline values during the anaesthetic period. No significant differences were observed in the recovery times. Morphine at 1 or 2 mg/kg combined with medetomidine and alfaxalone in rabbits produced a suitable level of anaesthesia, although profound cardiorespiratory depression was found.