Strongyle egg counts in Standardbred trotters: Are they associated with race performance?

Summary Reasons for performing study: Strongyle worm burdens are assumed to subclinically affect equine performance. This assumption appears to be particularly pronounced in the equine racing industry. Hypothesis: Race results of Standardbred trotters are negatively affected by high strongyle faecal egg count levels. Methods: Faecal samples were obtained from 213 racing Standardbred trotters, aged ≥2 years, and stabled at training facilities of 21 professional trainers with license at racecourses in Denmark. Strongyle egg counts were generated using a McMaster technique. Race results were recorded as the finishing position of the horse (position 1–3 vs. finishing lower) and winning purse. The effect of strongyle egg counts on performance was assessed using regression analyses. Results: Strongyle egg counts ranged from 0–3500 with a mean of 319 and a median of 150 eggs/g. Finishing in positions 1–3 was significantly associated with higher egg counts. Conclusions: Race performance of the population of professionally trained Danish Standardbred trotters was not negatively affected by higher strongyle faecal egg count levels. Potential relevance: The traditional frequent anthelmintic treatments of racehorses may be inordinate.