Efficacy of intranasal non-steroidal anti-inflammatory drugs on pain responses in castrated and tail-docked piglets

Abstract Routine piglet processing procedures, such as surgical castration and tail docking, are known to induce pain and stress, and non-steroidal anti-inflammatory drugs (NSAIDs) are commonly administered to mitigate these responses. This study evaluated the effects of processing and NSAID administration on physiological and behavioral indicators of pain and stress in male piglets. A total of 120 piglets (5 days old) were randomly assigned to one of eight treatment groups in a 2 × 4 factorial design, including sham or processed piglets receiving intranasal flunixin meglumine, ketoprofen, meloxicam, or saline solution. Piglets underwent surgical castration and tail docking or sham handling one hour after treatment administration. Plasma cortisol concentrations were assessed at baseline, 1 h, 3 h, and 24 h post-procedure, and pain-related behaviors were evaluated using the UNESP-Botucatu Pig Composite Acute Pain Scale (UPAPS). Processed piglets, both with and without NSAID administration, exhibited higher plasma cortisol concentrations than sham piglets at 1 h post-procedure, indicating an acute stress response, with concentrations returning to baseline by 3 h and 24 h. No treatment effects of NSAIDs were observed for cortisol concentrations. Behavioral assessment revealed higher UPAPS scores in processed piglets at 1 h, 3 h, and 24 h compared with sham piglets, indicating persistent pain-related responses. NSAID treatments did not consistently mitigate behavioral pain expression, although ketoprofen-treated piglets exhibited a transient reduction in UPAPS scores at 3 h post-procedure. Overall, piglet processing elicited acute physiological stress responses and sustained behavioral indicators of pain. These findings support the need for integrated analgesic strategies to more effectively mitigate post-procedural pain and improve piglet welfare.