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

Alexandra Geyer Flores,Vanessa Osmari,Sônia De Avila Botton,Fernanda Ramos,Fernanda Silveira Flores Vogel,Camila Balconi Marques,Denise Jaques Ramos,Luís Antônio Sangioni

doi:10.1590/s1984-29612020086

Alexandra Geyer Flores, Vanessa Osmari + Show 6 more

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https://doi.org/10.1590/s1984-29612020086

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Abstract

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.

Highlights

In Brazil, horses are being used for restoration of public order, military ceremonials, and equestrian sports, such as jumping competitions and riding competitions (Campos, 2017)
Considering the value of egg reduction per gram of feces (R-egg counts per gram of feces (EPG)) of less than 95% (Lyndal-Murphy et al, 2014), it was found out that parasitic resistance occurred in the treated groups with moxidectin (52.1% - G7), fenbendazole (1.99% - G8), while ivermectin was inconclusive (93.6% - G9) in Farm 1 in the young animal category
Our results demonstrated the resistance to moxidectin in young animals (52.1% - G7), and low efficacy in adult animals (90.1% - G4) in Farm 1

Summary

Introduction

In Brazil, horses are being used for restoration of public order, military ceremonials, and equestrian sports, such as jumping competitions and riding competitions (Campos, 2017). Parasitic infections represent significant economic losses that affect animal health by causing diseases such as diarrhea and colic and lead to weak physical conditions and performance (Barrett et al, 2004). The breeding systems of these animals are intensive, extensive, or semi-intensive, and can cause parasitic infections, especially in the first few weeks of life (Molento, 2005). Equines are susceptible to a variety of endoparasite genera that are located in different regions of the gastrointestinal tract. Strongyloides westeri, Strongylus spp., Parascaris equorum, and Anoplocephala spp. colonize the small intestine, and Anoplocephala spp., Oxyuris equi, Strongylus spp. and small strongyles (Cyathostominae) colonize the large intestine (Molento, 2005; Nielsen et al, 2014)

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