Transfusion of hyperimmune plasma for protecting foals against Rhodococcus equi pneumonia.
Authors: Kahn Susanne K, Cohen Noah D, Bordin Angela I, Coleman Michelle C, Heird James C, Welsh Thomas H
Journal: Equine veterinary journal
Summary
Rhodococcus equi pneumonia remains a significant challenge at breeding establishments worldwide, with no effective vaccine currently available; consequently, many farms employ transfusion of hyperimmune plasma (HIP) from vaccinated donor horses as a disease control strategy, though published evidence supporting its effectiveness has proven inconsistent. This 2023 narrative review by Kahn and colleagues examined foundational studies, synthesised current knowledge on HIP efficacy, explored reasons for variable outcomes across trials, and evaluated both protective mechanisms and transfusion-associated risks. Whilst the bulk of evidence favours HIP transfusion for reducing R. equi pneumonia incidence in foals, critical knowledge gaps persist regarding optimal plasma volume and dosing schedules, ideal timing of administration, and the specific immunological pathways conferring protection. The practice carries considerable practical drawbacks—it is costly, labour-intensive, and introduces transfusion risks to foals—making it an imperfect solution for endemic farm situations. Future development of alternative passive or active immunisation strategies is urgently needed to provide equine practitioners with more practical, safer, and more economical prophylactic options for this economically important disease.
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Practical Takeaways
- •Hyperimmune plasma can help reduce R. equi pneumonia incidence on endemic farms, but standardized protocols for dosing and timing are lacking—consult current farm data and veterinary guidance for your operation
- •Consider the significant costs and labor requirements of hyperimmune plasma transfusion when evaluating disease prevention strategies; explore emerging alternatives as they become available
- •Screen foals receiving hyperimmune plasma for transfusion reactions and complications, as this is an invasive procedure with documented risks
Key Findings
- •Weight of evidence supports hyperimmune plasma transfusion for preventing R. equi pneumonia in foals, though effectiveness varies considerably among studies
- •Critical knowledge gaps remain regarding optimal volume/dose, timing of transfusion, and specific protective mechanisms of hyperimmune plasma
- •Hyperimmune plasma transfusion is expensive, labor-intensive, and carries transfusion-related risks for foals
- •Alternative passive and active immunization approaches are needed as R. equi pneumonia lacks an effective vaccine