Clinical trial of efficacy of ivermectin pour-on against gastrointestinal parasitic nematodes in silvopasturing horses.
Authors: Francisco I, Sánchez J A, Cortiñas F J, Francisco R, Mochales E, Arias M, Mula P, Suárez J L, Morrondo P, Díez-Baños P, Sánchez-Andrade R, Paz-Silva A
Journal: Equine veterinary journal
Summary
# Editorial Summary Researchers evaluated the clinical effectiveness of ivermectin pour-on formulation against gastrointestinal nematodes in naturally infected grazing mares over a 21-week period, using faecal analysis (flotation, sedimentation and migration techniques) alongside haematological monitoring to assess treatment response. The ivermectin treatment completely suppressed egg shedding of ascarids and pinworms throughout the study duration, with strongyle eggs absent from treated animals between weeks 3 and 10, demonstrating robust efficacy against multiple parasite species encountered in pasture-based systems. Secondary benefits included significant increases in circulating red blood cells post-treatment and reduced leucocyte counts, suggesting the anthelmintic improved haematological parameters alongside parasite control; notably, no adverse effects were recorded. For equine professionals managing group-grazing situations—particularly in silvopasture systems where parasitic exposure remains high—this evidence supports pour-on ivermectin as a reliable therapeutic option, though practitioners should remain mindful of developing resistance patterns and continue to implement integrated parasite management strategies rather than relying solely on chemical intervention.
Read the full abstract on PubMed
Practical Takeaways
- •Ivermectin pour-on formulation provides effective control of major gastrointestinal nematodes in grazing horses and is suitable for treating large groups
- •Treatment produces measurable improvements in hematologic parameters (increased RBCs, decreased WBCs) indicating overall health benefit beyond parasite elimination
- •This formulation offers a practical therapeutic option for silvopastured or extensively managed horse herds with minimal adverse effects
Key Findings
- •Ivermectin pour-on suppressed egg elimination of ascarids and pinworms throughout the 21-week study period
- •No strongyle eggs were observed in the treatment group between weeks 3 and 10
- •Red blood cell counts increased significantly after anthelmintic therapy
- •Circulating leucocyte counts showed statistical reduction post-treatment with no observed side effects