The study was conducted to evaluate the post operative analgesia offered by tolfenamic acid and phenylbutazone for castration in equines so as to identify a suitable analgesic agent for field practice with welfare concern in equines. The study was carried out on twelve apparently healthy horses that were referred to Madras Veterinary College Hospital for castration. The horses were randomly allocated to two groups of six horses each. Both the groups received xylazine (1.1 mg/kg) followed by ketamine (2.2mg/kg) intravenously, as an anesthetic regimen and while Group I received phenylbutazone (4mg/kgb.wt, i.m) as an analgesic agent, Group II received tolfenamic acid (4mg/kgb.wt, i.v). The present study conducted evaluated the analgesic efficacy of tolfenamic acid and phenylbutazone by measuring its effects on physiological and haematological parameters. The horses in both the groups were studied for a period of four days. On day 0 (preoperative day), day 1 (the day of the surgery), days 2 and 3 (post operative days). All the recordings and measurements were performed approximately at the same time of the day to avoid the diurnalvariations.The parameters recorded were body temperature, body weight, mean heart rate and mean respiratory rate to assess the physiological status, PCV, Neutrophil: Lymphocyte ratio, Platelet count and eosinophil count to assess the hematological status. The data obtained were statistically analyzed using completely randomized block design and paired t – test. Significant increase in the body temperature, platelet count and a non significant increase in mean heart rate in both the groups were present post operatively on day 1, which were later found to decrease on days 2 and 3. The eosinophil count in both these groups was found to decrease significantly in group I and non significantly in group II post surgically on day 1 and increase back to normalcy on days 2 and 3. In conclusion, both these drugs were identified to be suitable analgesic agent for field practice that could alleviate pain during post operative period.