Analgesia encompasses drugs used to reduce perceived pain. The attribution of pain to non-mammalian vertebrates has widened markedly over the last 20 years, based on common nociceptive pathways, the presumption of evolutionary advantage in the experience of pain, and particularly, behavioral findings. Central processing of pain in non-mammalians is not well understood which has hindered both the attribution of pain and the emphasis placed on analgesia in non-mammalian vertebrates. Nociception (the processing of harmful stimuli, which does not require the emotive aspect of pain) triggers a wide-ranging physiological cascade that, irrespective of the attribution of pain, is sufficient to warrant the use of analgesic drugs. Consolidated research between physiologists and veterinarians is required into the dosages and efficacies of analgesics in the many and varied taxa of physiological interest.