Medetomidine/Buprenorphine to Preanesthetize Cats

This prospective, randomized, blinded clinical study evaluated the use of medetomidine-buprenorphine for effective preanesthesia in cats. Healthy cats (n = 40) were assessed during ovariohysterectomy in this prospective, randomized, blinded clinical study. Sedation scores were assigned before preanesthesia. Cats were randomized into groups on the basis of anesthetic type. Group M30 cats received 30 mcg/kg medetomidine, group M10+B cats received 10 mcg/kg medetomidine/20 mcg/kg buprenorphine, group M30+B cats received 30 mcg/kg medetomidine/20 mcg/kg buprenorphine, and group M50+B cats received 50 mcg/kg medetomidine/20 mcg/kg buprenorphine. Cats were housed in cages after injection and adverse effects were noted. Sedation scores were assigned after cats were removed from cages. Anesthesia was maintained with propofol and isoflurane, and atipamezole was administered to each cat after surgery. Recovery quality was assessed in all cats, and mild adverse effects were noted in all groups. Sedation scores before preanesthesia were similar in all groups, and required propofol doses did not differ significantly among groups. However, the amount of volatile gas agent required for the M30+B group was significantly lower than that for the M30 group. Significantly decreased heart rate data were noted in the M50+B group compared with the M30 group, and oxygen saturation values were significantly lower in the M50+B group than in the M30 group. Cats in the M+B groups had significantly smoother anesthetic recoveries than cats in the M30 group. This preanesthetic combination resulted in reduced volatile gas requirements and smoother anesthetic recoveries in healthy feline patients. Study supported by Alstoe Animal Health

COMMENTARY: This article discusses the use of several doses of medetomidine with and without buprenorphine at 0.02 mg/kg as premedication in cats. The findings that the addition of buprenorphine improved analgesia and recovery scores are not surprising. Because these drugs are commonly used in combination for sedation and premedication of healthy cats, this article is a useful contribution to the literature-particularly since it shows the apparent safety and lack of adverse effects of the protocol. One limitation of the study is that the authors chose to reverse the medetomidine after surgery was completed. It would have been better for postoperative analgesia to allow the dose to carry over into the recovery period, and it would have been interesting if the authors had evaluated the quality of recovery without reversal. Nevertheless, this drug combination, particularly at the dose combination of 10 to 30 mcg/kg of medetomidine and 20 mcg/kg of buprenorphine, should prove useful for practitioners. Medetomidine is not currently available, but the equivalent dosage of dexmedetomidine (5-15 mcg/kg or slightly higher) could probably be substituted with similar results.

Investigating medetomidine-buprenorphine as preanaesthetic medication in cats. Grint NJ, Burford J, Dugdale AHA. J SMALL ANIM PRACT 50:73-81, 2009.