Persistence of the efficacy of a moxidectin gel on the establishment of cyathostominae in horses.

The study investigated the effectiveness of an orally administered moxidectin gel in preventing the establishment of small strongyles in horses. The controlled trial found that the gel prevented infection for at least two, and potentially three, weeks.

Study Design and Procedure

• A controlled trial was conducted on nine worm-free foals, five of which were treated with a moxidectin gel of 2percent concentration, administered orally, at a dose of 0.4 mg/kg bodyweight. The remaining four foals served as the control group.
• For the duration of the experiment, that spanned over days 0, 7, 14, 21, and 28, all nine foals were infected experimentally with 200,000 small strongyles larvae.
• Three foals from the treated group and two foals from the control group were necropsied (autopsied) on day 42, while the remaining were necropsied on day 43.

Findings

• Examining the foals in the control group, fourteen species of small or medium-sized strongyles were discovered, with ten of these species present in all four control foals.
• The average rate of infection establishment was significantly lower in the treated foals (7 percent) compared to the control foals (27 percent).
• In terms of different growth stages (L3 and L4) of small strongyles, there was about an equal number of early and late L3 stages in each group. However, the control foals presented over ten times the amount of L4 stages compared to the treated group.
• The treatment with moxidectin resulted in no lumenal stages (a life cycle stage of the parasite found in the intestine) being found in the treated foals. In contrast, nearly half of the total parasite load in the control foals consisted of these stages.

Conclusion

• Based on the results, the study concludes that the moxidectin gel treatment effectively prevents the establishment of small strongyles in foals for a minimum of two weeks, and potentially up to three weeks.