Endoparasite control management on horse farms--lessons from worm prevalence and questionnaire data.
Authors: Fritzen B, Rohn K, Schnieder T, von Samson-Himmelstjerna G
Journal: Equine veterinary journal
Summary
# Editorial Summary Anthelmintic resistance in equine nematodes is now widespread enough that traditional blanket-treatment protocols warrant critical re-evaluation. Fritzen and colleagues surveyed 76 German horse farms (comprising approximately 2,000 horses) across 2003–2004, combining faecal nematode egg counts with detailed questionnaire data on management practices to identify which control strategies actually reduce parasite burden. Key findings revealed troubling patterns: yearlings on stud farms carried twice the risk of strongyle infection despite intensive treatment; more frequent anthelmintic dosing (≥3 times yearly) lowered strongyle counts only in mature horses, not younger stock; foals on farms using horse manure as fertiliser showed significantly higher *Parascaris equorum* infection; and yearlings on stud farms demonstrated incomplete faecal egg count reduction following treatment—a direct indicator of resistance. The authors conclude that sustainable parasite control demands a strategic shift away from reliance on chemical intervention alone, instead incorporating faecal egg count monitoring, quarantine protocols for new arrivals, and regular efficacy testing via faecal egg count reduction testing. These findings challenge the assumption that increased treatment frequency automatically improves outcomes and highlight age-dependent variations in drug efficacy that should shape individual farm protocols.
Read the full abstract on PubMed
Practical Takeaways
- •Increase anthelmintic treatment frequency alone is ineffective in foals and yearlings; combine with non-chemical parasite control strategies and regular faecal egg count monitoring
- •Avoid fertilising pastures with horse manure to reduce Parascaris equorum transmission, particularly for foals
- •Implement quarantine treatment and faecal egg count reduction testing for new arrivals to monitor for anthelmintic resistance development on your farm
Key Findings
- •Yearlings on stud farms showed 2-fold higher risk of strongyle faecal egg count positivity compared to other farm types
- •Higher anthelmintic treatment frequency (≥3 per year) reduced strongyle infection only in mature horses, not in foals or yearlings
- •Foals on farms using horse manure for pasture fertilisation had significantly higher risk of P. equorum infection
- •Yearlings on stud farms showed incomplete faecal egg count reduction following anthelmintic treatment more often than yearlings on other farm types