Methadone and Dexmedetomidine Combination as Premedicant Agents for Ovariectomy in Cats

Abstract

The purpose of this study was to assess sedative and analgesic effects produced by the association of methadone and dexmedetomidine, administered intramuscularly as premedication for ovariectomy in cats. Twenty-four healthy cats were enrolled in the study. The values of heart and respiratory rate were recorded as Tbase. Cats received methadone 0.5 mg kg^-1 and dexmedetomidine 5 mcg kg^-1 IM. Sedation and ease for catheterization were scored using a simple descriptive scale ranging from 0 (no sedation) to 3 (profound sedation) and 0 (very difficult) to 3 (very easy). General anesthesia was induced with propofol and after endotracheal intubation it was maintained with isoflurane. During the surgery Heart Rate (HR), Respiratory Rate (RR), hemoglobin oxygen saturation, Doppler blood pressure, expiratory isoflurane percentage and end tidal of carbon dioxide were recorded every five minutes. At the end of the surgery all animals received robenacoxib 2 mg kg^-1 subcutaneously. Recovery was scored using a simple descriptive scale ranging from 0 (poor) to 3 (excellent). The median sedation score was 2 (range 0-3); the only adverse effect associated with the premedication was vomiting occurred in 20% of the cats. No animals became excited after premedication. The median ease for catheterization was 3 (range 1-3). After premedication HR and RR showed a decrease of 28% and of 32%, respectively, in comparison to Tbase values. The median recovery score was 3 (range 1-3). No animal required additional analgesia after the surgery. The association of dexmedetomidine 5 mcg kg^-1 and methadone 0.5 mg kg^-1 employed in this study resulted in overall good sedation quality without any major adverse reaction. The onset of sedation was quite fast (about 7 min), suggesting synergic effect of the two molecules. Most of cats showed an easy catheterization and the recovery was excellent for the majority of cases.