Towards an improved pain assessment in castrated horses using facial expressions (HGS) and circulating miRNAs

Background Pain in horses is an emergent welfare concern, and its assessment represents a challenge for equine clinicians. This study aimed at improving pain through convergent validation of existing tools: we investigated whether effective analgesic treatment influences the horse grimace scale (HGS) concentration specific circulating microRNAs (miRNAs). Methods Eleven stallions underwent routine surgical castration under general anaesthesia. They were divided into two groups: with administration preoperative flunixin plus local injection mepivacaine spermatic cords. HGS levels seven miRNAs evaluated pre-, 8 20 hours post-procedure. Results Compared to pre-castration, HGS, miR-126-5p, miR-145 miR-let7e increased significantly receiving post-castration (Friedman test, p < 0.05). Both behavioural molecular changes occurred only, confirming that addition treatment. Conclusions Combining use miRNAs, particularly miR-145, could be meaningful monitor acute conditions horses. Our results further validate as method assess point out promising biomarker identify pain.