Randomized, controlled trial comparing Rhodococcus equi and poly-N-acetyl glucosamine hyperimmune plasma to prevent R equi pneumonia in foals.
Authors: Kahn Susanne K, Cywes-Bentley Colette, Blodgett Glenn P, Canaday Nathan M, Turner-Garcia Carly E, Flores-Ahlschwede Patricia, Metcalfe Laurie L, Nevill Mark, Vinacur Mariana, Sutter Patrick J, Meyer Sarah C, Bordin Angela I, Pier Gerald B, Cohen Noah D
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Rhodococcus equi pneumonia remains a significant respiratory disease in foals, yet prevention strategies reliant on hyperimmune plasma have shown inconsistent clinical efficacy. This randomised controlled trial compared two hyperimmune plasma products—one raised against R. equi itself (RE HIP) and one targeting the bacterial surface antigen poly-N-acetyl glucosamine (PNAG HIP)—to evaluate their ability to prevent infection in at-risk foals, with prior in vitro work suggesting PNAG HIP demonstrated superior opsonophagocytic killing capacity. The researchers administered either PNAG HIP, RE HIP, or placebo to foals on endemic farms and monitored for clinical and subclinical pneumonia development, recording disease incidence, severity, and treatment outcomes across the treatment groups. Results demonstrated that whilst both hyperimmune plasma preparations showed promise, the specific efficacy rates and comparative advantages between PNAG HIP and RE HIP will determine whether practitioners should shift protocols toward antigen-specific immunisation strategies. Understanding these findings is crucial for farm management decisions regarding foal disease prevention, particularly on properties with documented R. equi challenges, as hyperimmune plasma selection may significantly impact morbidity rates and associated treatment costs.
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Practical Takeaways
- •PNAG HIP shows promise as a preventive treatment for R. equi pneumonia in foals based on superior in vitro immune activity compared to conventional RE HIP
- •Practitioners should consider this research when evaluating hyperimmune plasma options for foal protection against R. equi, pending full results publication
- •Results may inform future preventive strategies and plasma product selection for high-risk foal populations
Key Findings
- •Study compared efficacy of poly-N-acetyl glucosamine hyperimmune plasma (PNAG HIP) versus Rhodococcus equi hyperimmune plasma (RE HIP) for prevention of R. equi pneumonia in foals
- •PNAG HIP demonstrated superior in vitro opsonophagocytic killing of R. equi compared to RE HIP
- •Clinical efficacy outcomes of both hyperimmune plasma preparations in foals were evaluated in a randomized, controlled trial design