Efficacy of preemptive analgesia with amantadine in the control of postoperative pain in cats undergoing ovariohysterectomy

Abstract Background Amantadine is effective in the treatment of nervous system disorders as it blocks NMDA receptors, showing potential as an analgesic agent by inhibiting central sensitization. The aim was to evaluate the preemptive effect of amantadine on postoperative analgesia in cats undergoing ovariohysterectomy and its influence on the physiological parameters of the treated animals. For this purpose, 20 healthy domestic cats, were divided into two sample groups with 10 animals each and referred for ovariohysterectomy. In the control group (CG) the cats orally received placebo capsules 30 minutes before the standard anesthetic protocol. In the amantadine group (AG) the animals orally received 5mg/kg of amantadine 30 minutes before the standard anesthetic protocol. The presence of adverse effects after administration of the capsule was evaluated. An intraoperative evaluation was performed at different times during the surgical procedure, assessing the following parameters: heart and respiratory rates, oxyhemoglobin saturation, end-tidal carbon dioxide, end-tidal isoflurane concentration, esophageal temperature, and systolic blood pressure. Post-surgical pain was assessed using the Visual Analog Scale and the Multidimensional Scale for the evaluation of post-operative pain in cats of the Universidade Estadual Paulista (UNESP) – Botucatu. Results Amantadine did not influence the evaluated physiological parameters. The group that received amantadine had lower pain scores on both scales when compared to the control group and required fewer analgesic rescues. Conclusions It was concluded that the preemptive, oral administration of amantadine, at a dose of 5mg/kg, was effective in controlling postoperative pain in cats undergoing ovariohysterectomy, without causing adverse effects or alterations in the physiological patterns of the treated animals.