Effect of plasma transfusion on serum amyloid A concentration in healthy neonatal foals and foals with failure of transfer of passive immunity.
Authors: Palmisano Megan, Javsicas Laura, McNaughten Justin, Gamsjäger Lisa, Renaud David L, Gomez Diego E
Journal: Journal of veterinary internal medicine
Summary
Serum amyloid A (SAA) is commonly used as an inflammatory marker in neonatal foals, yet anecdotal reports suggested that plasma transfusions artificially elevated SAA concentrations, potentially confounding clinical interpretation. Researchers prospectively enrolled 86 foals under 24 hours of age across three groups: 17 receiving fresh frozen plasma (FFP) for failure of transfer of passive immunity (FTPI; IgG <8 g/L), 33 receiving prophylactic plasma for *Rhodococcus equi* protection despite adequate immunity (IgG >8 g/L), and 21 healthy untransfused controls, measuring SAA before and 24 hours after transfusion. Contrary to clinical suspicion, FFP administration produced no significant changes in SAA concentration across any group, with baseline SAA levels remaining the strongest predictor of SAA at 24 hours—suggesting individual variation rather than transfusion-induced elevation. These findings reassure clinicians that SAA can continue to be interpreted as a valid inflammatory marker in neonatal foals regardless of plasma transfusion status, simplifying decision-making in FTPI cases where distinguishing infection from immune deficiency alone is diagnostically critical.
Read the full abstract on PubMed
Practical Takeaways
- •Plasma transfusions in neonatal foals do not artificially inflate SAA levels, allowing practitioners to continue using SAA as a reliable marker of infection or inflammation even in recently transfused foals
- •SAA concentrations at baseline predict SAA levels 24 hours later; initial SAA measurement is prognostically informative and can guide clinical decision-making
- •Administration of FFP for FTPI or R. equi prevention does not confound inflammatory markers, simplifying interpretation of laboratory results in treated foals
Key Findings
- •Administration of fresh frozen plasma (FFP) to neonatal foals was not associated with changes in serum amyloid A (SAA) concentration (P > 0.05)
- •No statistical differences in SAA concentration at baseline or 24 hours among healthy foals, foals receiving preventative plasma, or foals with FTPI (P > 0.05)
- •Foals with higher SAA concentration at baseline also had higher SAA concentration at 24 hours, indicating baseline SAA predicts follow-up SAA concentration (P < 0.05)
- •Hyperimmune FFP administration does not elevate SAA in either healthy neonatal foals or those with FTPI, supporting SAA use as an inflammation marker post-transfusion