Serum amyloid A as an aid in diagnosing sepsis in equine neonates.
Authors: Barr Bonnie, Nieman Natanya M
Journal: Equine veterinary journal
Summary
# Serum Amyloid A as a Diagnostic Aid in Neonatal Foal Sepsis Sepsis remains a major cause of death and illness in foals during the critical first week of life, yet early diagnosis is hampered by non-specific clinical signs that overlap considerably with other neonatal conditions. Barr and Nieman investigated whether point-of-care serum amyloid A (SAA) testing—measuring this well-established acute phase protein—could serve as a reliable biomarker for sepsis, conducting a retrospective analysis across four foaling seasons at both breeding and referral facilities. Septic foals (n=35) demonstrated markedly elevated median SAA concentrations of 114 µg/mL compared to just 1.5 µg/mL in sick non-septic foals (n=117) and 0 µg/mL in healthy controls (n=245), with the difference reaching statistical significance. Using a diagnostic threshold of 100 µg/mL, SAA testing achieved excellent specificity (97.5%) and high negative predictive value (93.7%), though sensitivity was more modest at 52.9%—meaning whilst a positive result strongly indicates sepsis, a negative result cannot reliably exclude it. For practitioners, this suggests SAA testing functions best as a confirmatory tool alongside clinical assessment and other diagnostic markers rather than a standalone screening test, particularly valuable when positive results support early antimicrobial intervention in those critical first hours of life.
Read the full abstract on PubMed
Practical Takeaways
- •Use SAA point-of-care testing as a supportive diagnostic tool for sepsis in neonatal foals within the first 36 hours of life—high specificity means positive results strongly suggest sepsis
- •An SAA result <100 µg/mL does not rule out sepsis (52.9% sensitivity); combine testing with clinical assessment and other diagnostic criteria for optimal decision-making
- •SAA testing helps differentiate septic foals from sick non-septic foals, enabling more targeted treatment decisions and potentially improving outcomes on breeding farms and in referral settings
Key Findings
- •Septic foals had median SAA concentration of 114 µg/mL, significantly higher than sick non-septic foals (1.5 µg/mL) and healthy foals (0 µg/mL)
- •At 100 µg/mL diagnostic threshold, SAA test demonstrated 97.5% specificity and 92.1% overall accuracy for sepsis detection
- •SAA sensitivity was 52.9% with positive predictive value of 75.0%, indicating usefulness as a diagnostic aid despite moderate sensitivity
- •Point-of-care SAA testing can be performed in neonatal foals <36 hours old to support clinical sepsis diagnosis