The leading cause of pneumonia in young foals is the subject of a new research project by Dr. Macarena Sanz, associate professor of veterinary clinical sciences.
Sanz’s research efforts will be funded by the Grayson-Jockey Club Research Foundation, one of the nation’s leading sources of private funding for equine medical research.
“Rhodococcus equi (R. equi) incurs significant costs for prevention and treatment while impacting the careers of racehorses and other equine athletes,” Sanz said.
With no vaccine available, many farms rely on transfusion of hyperimmune plasma (Re-HIP), but it’s true effectiveness under field conditions remain unclear.
Because RE-HIP does not prevent initial infection, lesions can be seen in the lungs of the foals using ultrasound examination.
“As a result, foals in the U.S. often receive early antimicrobial treatments for R. equi even after plasma administration,” she said. “This contributes to the emergence of resistant R. equi strains which are difficult to treat and result in high mortality rates.”
Sanz’s research will consist of a randomized, controlled, blinded field trial. The field trial will test the hypothesis that intravenous administration of hyperimmune plasma to newborn foals will decrease the cumulative incidence of pneumonia attributed to R. equi.
“This study seeks to evaluate the effectiveness of hyperimmune plasma in preventing pneumonia under real-world conditions,” Sanz said. “By clarifying whether Re-HIP truly reduces disease and the need for early antibiotic use, the results could lower treatment costs, improve foal health, and combat the growing problem of antibiotic resistance on farms.”
This impactful work has also secured highly competitive funding, representing only the fourth grant awarded to Iowa State University by the Grayson-Jockey Club Research Foundation, and the first since 2013, underscoring its importance to the equine industry.
May 2026