Serum cortisol concentrations in newborn foals are increased by transfusion with anti-rhodococcal hyperimmune plasma and inversely associated with immunoglobulin activity.
Authors: Sayre Kira C, Flores-Ahlschwede Patricia, Wethington Alexandra B, Kahn Susanne K, Bray Jocelyne M, Volding Devynn M, Ahlschwede Scott, Bordin Angela I, Cohen Noah D, Welsh Thomas H
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Cortisol Response to Anti-Rhodococcal Hyperimmune Plasma in Neonatal Foals Administration of Rhodococcus equi hyperimmune plasma (REHIP) significantly elevates serum cortisol in newborn foals, with concentrations more than doubling from a mean baseline of 21.9 ng/mL to 44.1 ng/mL post-transfusion—a physiological stress response that warrants closer examination of transfusion protocols. In a prospective study of 356 foals across 13 New York farms, researchers observed that larger transfusion volumes (2 L versus 1 L) produced proportionally greater cortisol elevation, and that baseline cortisol concentrations showed inverse correlation with serum globulin and anti-Rhodococcus immunoglobulin activity (IgG1 and IgG4/7), suggesting foals mounting stronger humoral immune responses experienced lower baseline stress markers. Notably, despite these measurable changes in cortisol and immunoglobulin parameters, neither pre- nor post-transfusion cortisol concentrations were associated with subsequent development of rhodococcal pneumonia in this cohort. For equine practitioners, these findings indicate that whilst REHIP transfusion reliably triggers an acute stress response, this immunological activation does not appear to compromise protection against Rhodococcus equi infection; however, the clinical significance of sustained cortisol elevation in neonates and potential implications for other metabolic or immune functions remain unexplored and merit further investigation before modifying current transfusion recommendations.
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Practical Takeaways
- •REHIP transfusion temporarily elevates cortisol in foals; monitor for stress responses, with higher elevations at 2 L doses
- •The inverse relationship between cortisol and immunoglobulin activity suggests a potential stress-immune trade-off, but this does not impair protection against rhodococcal pneumonia in clinical practice
- •Cortisol elevation alone should not be used as a predictor of rhodococcal pneumonia risk in transfused foals
Key Findings
- •REHIP transfusion significantly increased serum cortisol concentration from mean 21.9 ng/mL to 44.1 ng/mL (P < 0.05)
- •Post-transfusion cortisol was lower in foals receiving 1 L REHIP compared to 2 L REHIP (P < 0.05)
- •Pre-transfusion cortisol concentration was inversely associated with total globulins (r = -0.19) and anti-rhodococcal IgG1 (r = -0.22) and IgG4/7 (r = -0.16)
- •Cortisol concentrations were not associated with risk of rhodococcal pneumonia development in this foal population