Sedative and cardiorespiratory effects of dexmedetomidine and buprenorphine administered to cats via oral transmucosal or intramuscular routes

Objective To determine if buprenorphine plus dexmedetomidine administered via the oral transmucosal route produces sufficient sedation in cats so that students can insert intravenous catheters. Study Design Prospective, randomized, blinded, clinical trial. Animals Eighty-seven shelter-owned female cats aged 4-48 months, weighing 1.1-4.9 kg. Methods Cats were randomly allocated to two treatment groups based on route of drug administration: oral transmucosal (OTM), or intramuscular (IM). Buprenorphine (20 mu g kg-1) plus dexmedetomidine (20 mu g kg-1) were administered as pre-medicants via one of these two routes. Prior to and 20 minutes after drug administration, heart and respiratory rates, systolic arterial pressure, and posture were measured and recorded. Twenty minutes after drug administration the same variables plus each cat's response to clipper sound, clipping, and restraint were recorded; higher scores indicated more sedation. Results There were no significant differences between the two groups prior to pre-medication. Within each treatment group heart rate was significantly lower 20 minutes after treatment, but it did not differ significantly between the two groups. Twenty minutes after treatment, respiratory rate was significantly less in the OTM group, but did not differ significantly between the two groups. Systolic arterial pressure did not differ within or between the two groups at either time. Scores for posture increased significantly within both groups, and cats in the IM group had higher scores after treatment. Twenty minutes after treatment, cats in the IM group had higher scores for clipping and restraint than OTM cats. Ketamine (IM) was necessary to facilitate catheterization in 25% and 16% of cats in the OTM and IM groups, respectively, but this was not significantly different. Conclusions and clinical relevance Administration of dexmedetomidine plus buprenorphine by the OTM route is easy to perform, but produces less sedation than the IM route for IV catheterization in cats.