Serum amyloid A as an aid in diagnosing sepsis in equine neonates

BACKGROUND Sepsis is a significant cause of morbidity and mortality in neonatal foals, especially during the first seven days of life. Diagnosing sepsis in neonatal foals can be challenging because initial clinical signs are often ambiguous and non-specific. OBJECTIVES To determine if the major acute phase protein serum amyloid A (SAA) as measured by a point-of-care SAA testing device can be used as an evidence-based biomarker of sepsis. STUDY DESIGN Retrospective cohort. METHODS Clinical diagnosis of sepsis based on positive bacterial blood culture or a positive sepsis score was obtained and compared to SAA values in a population of neonatal foals on a breeding farm and referral hospital during four consecutive foaling seasons. A rapid, point-of-care blood test was used to measure SAA concentrations in neonatal foals <36 hours old that were clinically diagnosed as healthy, sick non-septic, or septic. RESULTS The septic foals (n= 35) had a median SAA concentration (114 µg/mL) that was significantly greater (P<0.05) than that for foals in the sick non-septic (n=117, 1.5 µg/mL) and healthy (n=245, 0 µg/mL) groups. At a diagnostic threshold of 100 µg/mL, the SAA test had a sensitivity of 52.9% (95% CI 36.5 -68.9), specificity of 97.5% (95% CI 95.0-99.0), positive predictive value of 75.0% (95% CI 56.2-87.5), negative predictive value of 93.7% (95% CI 91.2-95.5), and a test accuracy of 92.1% (95% CI 88.2-95.0). CONCLUSIONS The results of this study indicate that SAA is a useful aid in the diagnosis of sepsis in the neonatal foal.