Are Respiratory Clinical Signs in Horses Associated With Strongyle Egg Shedding Rates on Farms With Varying Egg Shedding Levels?
Authors: Sperl Corinna, Gerber Vinzenz, Drießlein David, Klima Andre, Becher Anne M
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Respiratory Signs and Strongyle Egg Shedding in Horses Whether horses displaying respiratory clinical signs shed fewer strongyle eggs remains contentious in the literature, with some studies suggesting an association between severe equine asthma and reduced faecal egg counts (FECs). Sperl and colleagues investigated this relationship across 209 horses on seven Bavarian farms, collecting 1,035 faecal samples over three and a half years and categorising animals using a validated owner-assessed respiratory signs index (HOARSI 1–4) before analysing FECs using modified McMaster methodology. Using generalised additive mixed modelling to account for known confounders—age, seasonality, pasture time, and pasture management—the researchers found no significant association between respiratory signs and egg shedding, though individual horse variation, age, and seasonal factors all significantly influenced FEC (P < 0.05); notably, the direction of any respiratory effect differed unpredictably between farms. These findings contradict several prior studies and suggest that the previously reported inverse relationship between respiratory disease and strongyle burden may be farm-specific or dependent on unmeasured genetic or immunological factors rather than universally applicable. For practitioners, this implies that respiratory status should not be assumed as an indicator of parasitic burden, and faecal monitoring remains essential for evidence-based anthelmintic decision-making regardless of clinical respiratory presentation.
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Practical Takeaways
- •Respiratory signs in horses should not be assumed as an indicator of reduced strongyle parasite burden; farm-level factors appear to influence this relationship differently
- •Individual horse factors and age are more reliable predictors of strongyle shedding than respiratory clinical signs alone
- •Parasite management protocols should account for farm-specific variables and seasonality rather than relying on respiratory status as a proxy for infection levels
Key Findings
- •Mean fecal egg counts (35-320 eggs per gram feces) varied significantly between farms
- •The association between respiratory signs and strongyle egg shedding was not statistically significant and varied in direction between farms
- •Horse individual effect, age, and seasonality were significant predictors of fecal egg counts (P < 0.05)
- •Results contradict prior studies suggesting an association between severe equine asthma and decreased strongyle egg shedding