This document is based on the study that was conducted to evaluate the post operative analgesia offered by tolfenamic acid and phenylbutazone for castration in equines, premedicated with xylazine and induced with ketamine by measuring various components that are considered to be general indicators of pain and stress such as plasma cortisol levels, oxidative stress responses, various physiological, haematological and biochemical variations so as to identify a suitable analgesic agent for field practice with welfare concern in equines.