Epidural analgesia with dexmedetomidine, alone or in combination with ropivacaine, in dogs undergoing tibial plateau leveling osteotomy (TPLO)

The analgesic efficacy of dexmedetomidine administered epidurally in dogs undergoing TPLO was compared in a prospective, randomized, blinded study. Thirty client-owned dogs undergoing TPLO were assigned to one of three epidural treatments (10 dogs each): group R (1 mg kg-1 0.5% ropivacaine), group RD (1 mg kg-1 0.5% ropivacaine and 2.5 µg kg-1 0.05% dexmedetomidine) and group D (2,5 µg kg-1 0.05% dexmedetomidine). Dilution was performed with sterile 0.9% saline to maintain a total volume of 0.2 mL kg-1. Nociception was assessed intra-operatively based on changes in HR, fr and MAP. When two of these parameters increased by more than 20% from baseline values, rescue fentanyl was administered IV (3 µg kg-1). Post-operative pain was assessed using the Glasgow composite pain scale (GCPS; Holton et al. 2001) and a visual analogue scale (VAS). Sedation was scored recorded using a modified Ramsey sedation scale (Ramsey et al. 1974). The medians of intra-operative physiologic parameters and post-operative pain scores were analyzed with Kruskal–Wallis, followed by Bonferroni tests. No dogs in RD, 2 dogs in R and 2 dogs in D required fentanyl. Postoperative sedation scores tended to be higher (p = 0.09) in groups D and RD as compared to group R. Postoperative analgesia scores were similar in all groups (GCPS p = 0.57; VAS p = 1.00). No significant differences were observed among the remaining parameters. Epidural dexmedetomidine at the dosage of 2.5 µg kg-1, alone or in combination with ropivacaine, provided a good perioperative analgesia in dogs undergoing TPLO.