Dose titration of moxidectin oral gel against migrating Strongylus vulgaris and Parascaris equorum larvae in pony foals.

This research article explores the efficacy of different dosages of moxidectin oral gel against two parasitic larvae infections in pony foals. The infections targeted were from Strongylus vulgaris and Parascaris equorum. The research confirmed that moxidectin was highly effective in all tested doses.

Experimental Design

• The study worked with pony foals that were experimentally infected with the parasites Strongylus vulgaris and Parascaris equorum, specifically 56 day old S. vulgaris larvae and 11 day old P. equorum larvae.
• Three different doses of moxidectin were used for testing: 300, 400, and 500 micrograms per kg of the pony’s live body weight. A control group was administered with the vehicle only.
• The pony foals were initially infected with 600 third-stage S. vulgaris larvae and subsequently with 3000 embryonated P. equorum eggs, this was carried out on Day 0 and Day 45 respectively.
• The various moxidectin treatments were given on Day 56 and necropsy examinations were performed on Day 91 to evaluate the effects.

Findings

• At necropsy, fourth and fifth-stage S. vulgaris larvae were found in the control ponies, located in the cranial mesenteric artery and its branches, and in nodules in the wall of the cecum and ventral colon. P. equorum larvae were found in the small intestine of control ponies.
• Moxidectin showed high efficacy against both S. vulgaris and P. equorum larvae at all dosage levels tested. The effect was almost total, showing 99.6-100% efficacy.
• It is noted that control ponies had comparatively low levels of P. equorum infections when compared to previous experimental infections. The authors theorize that the initial S. vulgaris infection on Day 0 may have had an impact on the later P. equorum infection on Day 45, contributing to this lower recovery.

Implications

• The results of this study show that moxidectin oral gel is a highly effective treatment against migrating S. vulgaris and P. equorum larvae in pony foals.
• The observation that the initial S. vulgaris infection affected the subsequent P. equorum infection suggests that further investigation into the relationship between these two parasitic larvae and their infections in ponies may be valuable.