Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil.

The research article reports a study about the effectiveness of various antiparasitic drugs used to control gastrointestinal nematode infections in equines, specifically the parasite cyathostomins, in two military establishments in Brazil. The study found multiple cases of resistance to these antiparasitic agents, indicating a need for more effective diagnosis and treatment methods.

Objective and Methodology

• The main aim of the study was to evaluate the effect of various types of antiparasitic agents on both young and adult animals. These included benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), and a combination of active ingredients (ivermectin + pyrantel pamoate).
• The study was carried out in two military establishments in Rio Grande do Sul, Brazil, over the course of a year, from January to December, 2018.
• The animals were treated every 30 to 90 days, and the effectiveness of the treatments was analyzed by counting the reduction in egg count in the faeces.
• Larvae were identified in both pre and post-treatment samples for further analysis.

Results

• The results showed multiple instances of resistance in cyathostomins to various antiparasitic agents. Younger animals demonstrated resistance to fenbendazole and moxidectin, while older animals showed resistance to fenbendazole and pyrantel pamoate.
• This indicates that current treatment methods are not entirely effective, due to the development of drug resistance in the parasites.

Implications and Recommendations

• The finding of multiple drug resistance suggests that there needs to be a clearer method of diagnosing and defining parasitic resistance to aid in the creation of prophylactic parasitic control strategies. Suppressing treatment with ATP coupled with integrated alternatives was proposed as a potential solution.
• The increase in parasitic resistance could be slowed with better control and treatment strategies, offering a more effective approach to managing gastrointestinal nematode infections.