Rhodococcus Equi: Challenges to Treat Infections and to Mitigate Antimicrobial Resistance.
Authors: Higgins Courtney, Huber Laura
Journal: Journal of equine veterinary science
Summary
Rhodococcus equi remains one of the most significant infectious threats to foal welfare and farm economics, particularly in endemic breeding regions, yet widespread antimicrobial screening and treatment of subclinically affected animals has inadvertently driven the emergence of multidrug-resistant (MDR) strains in both clinical isolates and farm environments across the United States. This 2023 review by Higgins and Huber examines the epidemiological shift towards MDR-R. equi and the limited therapeutic options now available for treating foals infected with resistant isolates, highlighting how current preventive protocols—whilst effective against susceptible strains—may be undermining long-term treatment efficacy. The authors stress that alternative treatment strategies remain scarce, and the environmental persistence and transmission dynamics of MDR strains on breeding farms remain incompletely understood, creating uncertainty about the true scope of the problem. Practitioners should recognise that reducing prophylactic and metaphylactic antimicrobial use in foal populations represents an essential but challenging shift in farm management, balanced against the immediate welfare risks of undetected subclinical infections. Implementing more targeted diagnostic and treatment approaches—rather than blanket antimicrobial strategies—will be crucial for preserving drug efficacy and supporting antimicrobial stewardship across equine breeding operations.
Read the full abstract on PubMed
Practical Takeaways
- •Reconsider routine antimicrobial treatment of subclinically affected foals on your farm; this practice drives MDR-R. equi emergence with limited treatment alternatives available
- •Implement targeted ultrasound screening protocols but reserve antimicrobial therapy for clinically affected foals rather than prophylactic treatment of all detected cases
- •Collaborate with your veterinarian to develop farm-specific antimicrobial stewardship plans that balance disease prevention with resistance mitigation
Key Findings
- •Rhodococcus equi is one of the most common causes of pneumonia in young foals and poses significant economic and welfare threats to horse-breeding farms
- •Wide use of antimicrobials to treat subclinically affected foals has contributed to the emergence of multidrug-resistant R. equi in both clinical isolates and farm environments
- •Treatment alternatives for foals infected with MDR-R. equi are scarce, and the environmental impact of MDR-R. equi emergence on farms remains poorly understood
- •Reduction of antimicrobial use at horse-breeding farms is essential for preserving antimicrobial efficacy and protecting human, animal, and environmental health