Analgesic effect of intra-articularly administered morphine, dexmedetomidine, or a morphine-dexmedetomidine combination immediately following stifle joint surgery in dogs.

Soto N1, Fauber AE, Ko JC, Moore GE, Lambrechts NE.
J Am Vet Med Assoc
2014 Jun 1

Objective-To compare the analgesic effects of intra-articularly administered saline (0.9% NaCl) solution, morphine, dexmedetomidine, and a morphine-dexmedetomidine combination in dogs undergoing stifle joint surgery for cranial cruciate ligament rupture. Design-Randomized, controlled, clinical trial. Animals-44 dogs with cranial cruciate ligament rupture that underwent tibial tuberosity advancement (TTA) or tibial plateau leveling osteotomy (TPLO). Procedures-Dogs received intra-articular injections of saline solution (0.2 mL/kg [0.09 mL/lb]), morphine (0.1 mg/kg [0.045 mg/lb]), dexmedetomidine (2.5 μg/kg [1.14 μg/lb]), or a combination of morphine (0.1 mg/kg) and dexmedetomidine (2.5 μg/kg). Intra-articular injections of the stifle joint were performed after completion of the corrective osteotomy procedure, just prior to skin closure. Signs of pain were assessed every 2 hours thereafter on the basis of mean behavioral and objective pain scores. Dogs with pain scores exceeding predetermined thresholds were given hydromorphone (0.05 mg/kg [0.023 mg/lb], SC) as rescue analgesia. Results-Time to rescue analgesia did not significantly differ between dogs that underwent TTA versus TPLO. No significant difference in time to rescue analgesia was found among dogs receiving intra-articular injections of dexmedetomidine (median, 6 hours; range, 2 to 10 hours), morphine (median, 7 hours; range, 4 to 10 hours), or saline solution (median, 5 hours; range, 4 to 10 hours). However, time to rescue analgesia for dogs receiving intra-articular injection of the morphine-dexmedetomidine combination (median, 10 hours; range, 6 to 14 hours) was significantly longer than the time to rescue analgesia for other treatment groups. Conclusions and Clinical Relevance-Intra-articular administration of the morphine-dexmedetomidine combination provided longer-lasting postoperative analgesia, compared with either morphine or dexmedetomidine alone, in dogs undergoing TTA or TPLO. (J Am Vet Med Assoc 2014;244:1291-1297).