Evaluation of substance P as a biomarker for pain in equine colic.

Authors: Gruber Nina, Gesell-May Stefan, Scholler Dominik, Zablotski Yury, May Anna

Journal: Journal of equine veterinary science

DOI: 10.1016/j.jevs.2023.104979 PubMed: 38072227Log in to save

Summary

# Substance P fails to validate as a pain biomarker in equine colic Objective assessment of pain severity in equine colic remains challenging despite the availability of clinical grading scales, yet a reliable biochemical marker could improve clinical decision-making and prognostic accuracy. Gruber and colleagues recruited 30 warmblood horses stratified into mild, moderate, and severe colic groups (n=10 each) based on the Equine Acute Abdominal Pain Scale (EAAPS), collecting blood samples at hourly intervals over four hours and measuring substance P (SP) alongside established prognostic parameters including heart rate, serum cortisol, and blood lactate. Contrary to their hypothesis, SP concentrations remained stable throughout the monitoring period and demonstrated no correlation with EAAPS grading, haemodynamic changes, or established stress markers—whereas heart rate, cortisol, and lactate all increased proportionally with pain severity. These findings suggest that substance P, despite its established role as a neuropeptide in pain signalling pathways, lacks the clinical utility as an objective pain biomarker in colic cases. Practitioners should continue relying on integrated clinical assessment combining physical examination findings, established laboratory parameters, and pain scales rather than expecting a single biochemical marker to quantify colic pain severity or predict outcome.

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Practical Takeaways

•Substance P cannot be used as a clinical biomarker to objectively assess pain severity in colic cases; continue relying on established parameters (heart rate, cortisol, lactate) and clinical pain scales (EAAPS).
•While standardized pain assessment scales are valuable, practitioners should recognize that no single biochemical pain marker has yet been validated for equine colic, necessitating multimodal evaluation approaches.

Key Findings

•Substance P concentrations did not increase with pain severity and showed no correlation with EAAPS pain scores in 30 horses with mild, moderate, or severe colic.
•Established biomarkers (heart rate, serum cortisol, blood lactate) demonstrated expected increases with colic severity, while substance P remained stable regardless of clinical signs or disease progression.
•Substance P is not a reliable biomarker for reflecting painful conditions or predicting outcomes in equine colic cases.

Conditions Studied

equine colicacute abdominal pain

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