Assessment of Analgesic Efficacy of Intra-articular Tramadol Administration Following Arthroscopic Surgery in Horses - A Pilot Study

Objective- The aim of this study was to evaluate the analgesic efficacy of intra-articular administration of tramadol in horses following arthroscopic surgery. Design- Experimental study. Animals- Ten Warmblood horses Procedures- Horses underwent arthroscopic surgery of the tarsocrural joint (TCJ) (8 horses) and metacarpo- metatarsophalangeal joint (MCPJ/MTPJ) (2 horses). Intra-articular tramadol (2 mg/kg) or saline was administered in randomly selected horses (5 in each group; 4x TCJ and 1x MCPJ/MTPJ) under general anesthesia prior to recovery. After the horses were fully recovered and had returned to the stable two observers, blinded to the treatment scored pain independently at 1, 2, 3, 4, 6, 8, 12 and 24 hours based on a composite measure pain scale (CMPS). Results- Significant difference in pain score (P < 0.001) was observed at any individual time-point between the two groups, except at 24 hours post treatment. A significant lower pain score was detected in tramadol treated group (P < 0.001), up to the twelfth hour after treatment. No significant difference was seen between various times in the saline group (P = 0.09). Conclusion and Clinical Relevance- Analgesic efficacy of intra-articular tramadol administration was demonstrated by significantly reduced pain scores following arthroscopic surgery in horses. This observation might be useful as basis for a multimodal analgesic protocol; however, more detailed studies are warranted.