Serum Sialic Acid as a Biomarker of Inflammation and Infection: Insights From Veterinary Medicine

Serum sialic acid (SSA) levels, including total sialic acid (TSA), lipid-bound sialic acid (LBSA), and protein-bound sialic acid (PBSA), have been extensively studied as biomarkers of inflammation and infection across various species and diseases. In parasitemic sheep, elevated SSA levels likely reflect host-pathogen interactions and immune activation. Contrasting findings in bovine theileriosis demonstrated increased sialic acid (SA) levels during acute infections but decreased levels in severe parasitemia, suggesting variable responses based on parasitemia rates. SSA and LBSA levels in dogs significantly increase in babesiosis and dirofilariasis, indicating tissue damage and oxidative stress. Babesiosis, a tick-borne infection, shows SA elevations associated with inflammation and red blood cell destruction. Dirofilariasis, a heartworm disease, shows elevated SSA and LBSA levels, highlighting the importance of acute-phase proteins in disease severity. In avian species, diseases like Newcastle disease virus (NDV) infection, infectious bronchitis virus (IBV) infection, and bacterial challenges caused significant increases in SSA, LBSA, and PBSA levels, with LBSA showing the most pronounced changes, indicating its high sensitivity to inflammatory processes. Japanese quail with omphalitis also demonstrated elevated LBSA, highlighting its diagnostic potential in avian inflammation. Cattle with conditions such as traumatic reticuloperitonitis, acute metritis, pneumonia, and babesiosis exhibited markedly elevated SA and APP levels, consistent with findings in mastitis, colisepticemia, and leptospirosis, where APP levels correlated with disease severity. Tissue damage associated with increased SA is closely linked to inflammation and infection. These changes may also influence receptor-ligand interactions during infection, supporting SA as a useful biomarker for disease monitoring.