Evaluación intra y postoperatoria del efecto del tramadol administrado en dosis única y en infusión continua en conejos (Oryctolagus cuniculus)

Abstract

Tramadol is widely used in the companion animal clinic; however, there are still few studies validating its efficacy in rabbits, currently popular pets. Therefore, this research evaluated the intraoperative and postoperative analgesic effect of tramadol administered in single dose and continuous infusion in rabbits submitted to orchiectomy. For the intraoperative evaluation, cortisol and blood glycemia levels were measured pre and post-surgery; and changes in heart rate (HR) and respiratory frequency (RF) were measured taking 4 measurements during the 15 minutes of surgery. On the other hand, the post-surgical evaluation was performed through the "Rabbit Grimace Scale" (RbtGS) and the changes in heart rate (HR) and respiratory frequency (RF), every 30 minutes until completing 4 measurements. Twenty-one "Lion's head" male rabbits were selected, with a mean age of 5±1 months and with an adaptation process of 1 month to reduce the stress factor. Animals (n=7) were randomly assigned to 3 different treatments (T1= control without tramadol; T2= a single pre-surgical dose of 5mg/kg/IV; T3= loading dose of 2mg/kg/IV with a continuous infusion of 0.022 mg/kg/min). The results showed that using tramadol in rabbits, allows to obtain significantly lower means (P<0.05) in most of the evaluated parameters compared to T1. However, T2 and T3 have comparable analgesic effects intraoperatively, but T2 being superior in the postoperative evaluation. In conclusion, the use of tramadol at 5mg/kg preoperatively controls pain in rabbits in simple surgeries such as orchiectomy.