Demonstration of reduced efficacy against cyathostomins without change in species composition after pyrantel embonate treatment in Swedish equine establishments.

The research article discusses the reduced effectiveness of pyrantel embonate, an anthelmintic drug, against a type of horse parasite known as cyathostomins. Despite lower usage of the drug in Sweden, their study still found resistance in more than half of the studied farms.

Objective and Methodology of the Research

• The objective of this study was to understand the effectiveness of the anthelmintic drug, pyrantel embonate, against cyathostomin infection in horses in Sweden.
• This was done using two main techniques: fecal egg count reduction tests (to quantify the number of parasites before and after drug treatment) and metabarcoding (to identify different species of cyathostomins).
• Sixteen farms with at least six horses were included in the study, with each horse excreting a minimum of 100 eggs per gram of feces (indicating presence of parasites).

Findings of the Research

• Following the World Association for the Advancement of Veterinary Parasitology guidelines, pyrantel resistance was observed in nine out of sixteen farms, showing that more than half of the farms in the study experienced resistance. Seven farms showed full susceptibility to the drug.
• It was also observed that farms with low biosecurity measures (measures intended to prevent the spread of diseases) had significantly lower efficacy of pyrantel treatment.
• On analyzing the species composition, the most common cyathostomin species identified were Cylicocyclus nassatus and Cyathostomum catinatum, which accounted for 68% of all sequence reads prior to treatment. However, the treatment did not significantly affect the species composition, meaning resistance to the drug wasn’t species-specific.

Crucial Insights and Implications

• The results shed light on the importance of efficiency testing of drugs like pyrantel embonate, even when selective anthelmintic treatment and low treatment intensity methods are employed on the farm. This is to ensure that the drug is still effective in combating the parasites and that resistance isn’t building.
• The research also highlights the potential for parasite resistance against commonly used drugs, indicating a need for continuous monitoring and development of alternative treatment strategies.

This research, therefore, provides crucial insights that can help shape efforts to prevent and control cyathostomin infections in horses.