Post craniotomy pain management in Copenhagen rat by intraperitoneal or oral dosage of Tramadol: a comparative evaluation

Calvarial craniotomy in animal models involves pain and distress. Moderate to severe pain in laboratory animals requires adequate pain management strategies. According to previous studies, the options available for suitable analgesia for rat calvarial craniotomy are very few. For most analgesic treatments, injectable routes of administration are predominantly used. However, these routes require restraining the animals, which may cause unnecessary pain, distress and suffering. As a well-fare measure, we focused on pain management by oral administration of analgesia. In this particular study, which is a sub-study of a major experiment on bone regeneration with different polymeric scaffold materials, we have compared the analgesic efficacy of intraperitoneal (I/P) and oral administration of tramadol (10 mg/kg) over a period of 96 h post-surgery in rat craniotomy models. The focus of our study is to evaluate the potential pain reduction efficacy of orally administered Tramadol without any restraining involved. We have used various non-invasive methods to assess the pain-alleviating efficacy of tramadol administered through different methods. We found that the efficacy of oral administration of tramadol is comparable to I/P administration in alleviating pain. Additionally, oral administration through drinking water has the benefit of not putting the animal under unwanted restraining stress.