Anaesthetic and cardiorespiratory effects of romifidine/ketamine combinations in cats

Abstract

ObjectiveTo study the anaesthetic and cardiorespiratory effects of intramuscular (IM) administration of different combinations of romifidine and ketamine in cats. Study designProspective, randomized, cross-over experiment. AnimalsSeven healthy adult cats weighing (mean ± SD) 3.4 ± 0.7 kg and aged 4.6 ± 3.2 years. MethodsAnimals received romifidine 100 μg kg−1 with ketamine 7.5 (R100/K7.5) and 10 mg kg−1 (R100/K10), romifidine 200 μg kg−1 with ketamine 5 (R200/K5), 7.5 (R200/K7.5) and 10 mg kg−1 (R200/K10) by IM injection. The time required to perform orotracheal intubation (IT) was measured and the ease of intubation assessed. The onset of anaesthesia (OA), duration of anaesthesia (DA) and anaesthesia recovery times (AR) were measured. Analgesia and muscle relaxation scores were recorded every 5 minutes for 60 minutes after OA. Heart rate, systolic arterial pressure, arterial haemoglobin saturation, respiratory rate, end-tidal carbon dioxide and oesophageal temperature were also measured. ResultsThe IT, OA and DA were not significantly different between the treatments. The analgesia and muscle relaxation scores were similar between all treatments at most time points. The cardiorespiratory variables were not significantly different between the treatments in most cases. The adverse effects were dose dependent and similar to those previously described for other combinations of α2-agonists and ketamine. Conclusions and clinical relevanceAnaesthesia produced by the studied combinations of romifidine and ketamine may only be reliable when conducting brief and noninvasive procedures in cats. The OA times were slower and the DA shorter than those reported for other alpha-2 agonists combined with ketamine. A dose-related increase in the intensity of the anaesthetic effects could not be demonstrated in this study.