Assessment of the immunocrit method to detect failure of passive immunity in newborn foals.
Authors: Mortola Eduardo, Miceli Graciela, Alarcon Laura, Azcurra Mirian, Larsen Alejandra
Journal: Equine veterinary journal
Summary
# Assessment of the Immunocrit Method to Detect Failure of Passive Immunity in Newborn Foals Failure of passive transfer (FPT) — inadequate absorption of colostral immunoglobulins — represents a significant health risk in neonatal foals, with a critical window of only 8 hours post-birth for optimal intestinal absorption before this capacity deteriorates and closes entirely by 24 hours. Mortola and colleagues evaluated the immunocrit method as a practical field-based screening tool against conventional quantitative immunoglobulin measurement, recognising that equine practitioners require a rapid, cost-effective diagnostic rather than precise numerical immunoglobulin values across the full concentration spectrum. The immunocrit technique proved sufficiently reliable for identifying clinically significant FPT at the point of care, offering advantages in speed and accessibility compared to laboratory-dependent methods. For farriers, veterinarians and other equine professionals involved in neonatal assessment, this work validates a pragmatic testing approach that facilitates timely intervention when foals present with borderline or suspected inadequate colostrum intake — enabling plasma transfusion or immunoglobulin supplementation before systemic infection becomes established. The method's suitability as a field test underscores the importance of early neonatal evaluation protocols and supports evidence-based decision-making when passive immunity status cannot be definitively assessed through clinical observation alone.
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Practical Takeaways
- •Test foals for passive immunity failure within the first 24 hours of life using the immunocrit method as a quick field-side screening tool
- •Be aware that colostrum absorption is maximal only in the first 8 hours post-partum, making early colostrum intake critical for foal survival and health
- •Use the immunocrit method to rapidly identify at-risk foals rather than waiting for quantitative immunoglobulin concentration results, enabling timely intervention
Key Findings
- •Maximal absorption of colostrum immunoglobulins occurs within 8 hours after birth in newborn foals
- •Immunoglobulin absorption progressively decreases after 8 hours and becomes null after 24 hours post-partum
- •A simple, quick, inexpensive field test (immunocrit method) is needed to identify foals with failure of passive transfer rather than quantitative assessment