Efficacy of pyrantel pamoate and ivermectin paste formulations against naturally acquired Oxyuris equi infections in horses.

This research study tested the effectiveness of two types of paste treatments for naturally acquired pinworm infections in horses. The study outcomes proved that both treatments were successful in eradicating both adult and larval stages of pinworms, disproving anecdotal suggestions of these worms’ resistance to such treatments.

Introduction

• The study was motivated by observational reports that suggested certain treatments for equine pinworms (Oxyuris equi) were failing to deliver expected results.
• Before this study, there had been no formal evidence to confirm or deny the existence of anthelmintic resistance in equine pinworms.

Study Method

• 21 horses, ranging from 4 months old to 15 years old, were included in the study. All horses were naturally infected with pinworms.
• The horses were separated into three distinct groups. Group 1 horses received an oral paste of pyrantel pamoate, group 2 were untreated controls, and group 3 received an oral paste of ivermectin.
• The results of the treatment were gauged by comparing post-treatment worm counts of treatment groups to control animals.

Findings

• Following treatment, a significant decrease was observed in the number of adult pinworms across horses treated with either paste, suggesting high efficacy of both treatments.
• Paste of pyrantel pamoate showed an efficacy of 91.2%, while the ivermectin paste boasted slightly higher efficacy at 96.0%.
• In addition, both of these treatments demonstrated over 99% efficacy against the fourth-stage larvae of O. equi.

Conclusion

• This empirical study contradicts the anecdotal evidence that was suggesting potential resistance of pinworms against these widely adopted treatments.
• The results of this research indicate that the tested paste formulations of pyrantel pamoate and ivermectin are both extremely effective in treating equine pinworm infections.
• The high efficacy of both these treatments against adulticidal and larvicidal forms suggest that there is no macrocyclic lactone or pyrimidine resistance in the pinworm populations.