Evaluation of the clinical efficacy and safety of dexmedetomidine or medetomidine in cats and their reversal with atipamezole

Objective To evaluate and compare the clinical effects of dexmedetomidine (DEX) and medetomidine (MED) in cats, and their reversal with atipamezole (ATI). Study design Prospective blinded randomized multi-centre clinical trial. Animals One hundred and twenty client-owned cats. Methods Cats were randomly allocated to receive a single intramuscular (IM) injection of either DEX (0.04 mg kg(-1), n = 62) or MED (0.08 mg kg(-1), n = 58) for minor procedures requiring sedation and analgesia. Afterwards, ATI (0.2 mg kg(-1)) was administered IM to half the cats, randomly assigned. Prior to, during and after the procedure the sedative, analgesic and cardiorespiratory effects and body temperature were assessed. Results Dexmedetomidine and MED produced clinically and statistically comparable effects. The intended procedure(s) could be performed in over 90% of cats. Sedation and analgesia were apparent within 5 minutes, peak effects were observed at approximately 30 minutes and spontaneous recovery occurred by 180 minutes of injection. Heart and respiratory rate and body temperature decreased significantly over time and had not returned to baseline values 180 minutes after administration. ATI administration completely reversed the sedative and analgesic effects, returned the heart rate to normal and prevented any further reductions in respiratory rate and body temperature in both DEX- and MED-treated cats. The reporting of adverse events was low and the most commonly observed event was vomiting (7%). No serious adverse events or concerns regarding safety were reported. Conclusions and clinical relevance Dexmedetomidine (0.04 mg kg(-1)) produced comparable sedative and analgesic effects to MED (0.08 mg kg(-1)) in cats. DEX produced adequate sedation and analgesia for radiography, grooming, dental care and lancing of abscesses. ATI fully reversed the clinical effects of DEX.