The importance of anthelmintic efficacy monitoring: results of an outreach effort.

This study shows the transformation of equine parasitic control practices following an educational program that emphasized the importance of monitoring the effectiveness of deworming medications. The researchers found that the participating horse owners successfully reduced the amount of deworming medications used on the farm, while also discovering the resistance level of three common deworming drugs.

Context and Methodology

• The research evaluated the effects of an educational program organized by the Penn State Extension designed to teach horse owners about fecal egg counts (FECs) and fecal egg count reduction tests (FECRTs), which are used to monitor the efficacy of deworming treatments and the presence of resistant worm species in horses.
• Participating horse owners were subjected to a survey both pre and post study to understand their parasitic control practices and to collect data about their horses and farms. FECs were performed at three time points.
• Only those horses that had a strongyle egg count of over 300 per gram in their feces were treated with one of three common anthelmintic (deworming) drugs, namely pyrantel pamoate, fenbendazole, or ivermectin. The efficacy of these treatments was then evaluated via FECRTs two weeks post-treatment.

Results and Implications

• Before participating in the educational program, only 30.6% of the farms utilized FECs. Following the program, 97.3% of farms expressed an intention to use FECs moving forward. This shows the effectiveness of education in transforming existing practices.
• Additionally, participating farms were able to reduce the average number of deworming treatments given to their horses from 4.1 per year to less following the study. This reduction is directly related to the increased adoption of FECs, which enables farmers to treat only those horses that require it, rather than administering general prophylactic treatments.
• Analysis of the efficacy of the three anthelmintic drugs demonstrated widespread resistance, especially against fenbendazole (which worked on zero farms) and pyrantel pamoate (effective only on 7.4% of farms). Ivermectin was found to be the most effective treatment, working on 92.9% of farms.
• The massive collected data on anthelmintic resistance is a crucial contribution to the scientific community’s understanding of anthelmintic resistance levels, which is important to guide evidence-based recommendations for equine parasitic control.