Designing a field trial of an equine grass sickness vaccine: A questionnaire-based feasibility study.
Authors: Ireland Joanne L, McGorum Bruce C, Proudman Christopher J, Newton J Richard
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Feasibility of an Equine Grass Sickness Vaccine Trial Equine grass sickness (EGS) remains a significant welfare concern with no proven preventative strategy, making a rigorous randomised controlled trial of *Clostridium botulinum* type C vaccination essential—yet such trials require careful planning to be logistically viable. Ireland and colleagues surveyed 119 British equine veterinary practices to assess whether a nationwide RCT was feasible, examining case exposure, diagnostic confidence, and willingness to participate in vaccine efficacy research. The results were encouraging: 73% of practices had seen at least one EGS case in the preceding two years (median four cases), over half regularly attended recurrently affected premises, and 92.9% expressed willingness to participate in a trial, with 91% willing to assist in owner recruitment. However, notable gaps emerged in diagnostic confidence, particularly for chronic EGS presentations, and a small proportion of non-participating practices cited concerns about client engagement and administrative burden as barriers. These findings provide strong evidence that a field-based vaccine trial is feasible in Britain, with sufficient case exposure and practitioner support to justify progression, though trial designers should account for diagnostic variability and streamline data collection protocols to maximise compliance.
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Practical Takeaways
- •EGS is a sufficiently common problem in British equine practice to support a vaccine trial, with strong professional support (92.9% willing to participate)
- •Veterinarians report greater diagnostic confidence with acute/subacute EGS than chronic presentations, suggesting need for clearer chronic case diagnostic criteria
- •A nationwide RCT of C. botulinum vaccination is feasible based on practice distribution, case frequency, and veterinary engagement
Key Findings
- •73% of surveyed British equine practices had attended ≥1 EGS case within 2 years (median four cases)
- •91% of respondents considered a proposed EGS vaccine RCT important/very important to equine veterinary research
- •92.9% of practices indicated willingness to participate in a vaccine RCT
- •51.3% of practices regularly attended recurrently affected premises suitable for trial inclusion criteria