Beyond Lesions: Systemic Inflammatory and Metabolic Characterization of Swine Inflammation and Necrosis Syndrome

Swine Inflammation and Necrosis Syndrome (SINS) is characterized by multifocal inflammatory lesions in pigs of different ages and has been associated with systemic inflammatory processes. Therefore, the objective of the present study was to characterize associations between SINS expression and systemic inflammatory, hematological, and metabolic biomarkers in pigs from two farm cooperatives within the same commercial production system. In this exploratory study, 45 undocked piglets were assessed during the suckling and weaner stages. Clinical lesions were quantified across multiple body regions, and clinical-chemical and hematological parameters were analyzed in weaners. LASSO regression identified Pig major acute phase protein (PigMAP) as the biomarker most strongly associated with SINS-related traits, showing positive associations with tail base bristle loss and teat redness, whereas heel swelling and tail tip reddening were negatively associated or showed no association. Additional findings included decreased creatinine and urea under more favorable environmental conditions, and differences in bilirubin, creatine kinase (CK), lactate dehydrogenase (LDH), and glutamate dehydrogenase (GLDH) under less favorable conditions, indicating distinct patterns of clinical-chemical parameters associated with SINS. Platelet counts were lower in piglets with SINS status 2, i.e., piglets showing clinical signs of SINS during both the suckling and nursery periods, with statistically significant differences in the respective comparisons. These findings are consistent with the concept of SINS as a systemic inflammatory condition accompanied by measurable hematological and metabolic alterations. Together, these findings broaden the biological characterization of SINS and provide a foundation for future longitudinal studies investigating the temporal relationships between clinical manifestations and systemic biomarkers.