Anthelmintic resistance in Creole horses in the South of Rio Grande do Sul, Brazil

J.S Lignon,N.F Gonçalves,M.S Leão,F.G Pappen,J.L.T Camassola,T.A Antunes,T.G Pellegrin,D.M Pinto,P.K Ripoll,L.L Cunha

doi:10.1590/1678-4162-12247

Abstract

ABSTRACT The objective of the study was to evaluate the antiparasitic resistance against horse nematodes in the South of Rio Grande do Sul, Brazil. The results concerning the tests of anthelmintic efficacy on horses, stored in the database of the Parasitic Diseases Study Group (GEEP) - Veterinary Faculty, at the Federal University of Pelotas (UFPel), were carried out in the laboratory from 2018 to 2019. Stool samples were received from farms with breeding of adult female and male Criollo horses naturally infected, located in municipalities in the country’s southern region. The antiparasitic agents tested were Triclorfon + Fenbendazole, Closantel + Albendazole, Ivermectin + Praziquantel, Fenbendazole, Ivermectin, Doramectin, Mebendazole and Moxidectin. Techniques such as Gordon and Whitlock, Coproculture and Fecal Egg Count Reduction Test were performed. Of all the antiparasitic drugs tested, it was observed that only treatments with Ivermectin 2% showed desired values. The observed results indicate that resistance to macrocyclic lactones is usual in equine parasites in this Brazilian region, despite the results with isolated Ivermectin.

Highlights

In Brazil, the horse market provides financial incomes of approximately R$ 15 billion per year through a population of more than 5 million animals, being 9.2% of this amount located in Rio Grande do Sul state (RS) (Brasil, 2016)
Given the importance related to losses caused by parasitic diseases and the lack of a new anthelmintic chemical group for horses, the objective of the study is to evaluate the effectiveness of antiparasitic against equine nematodes in the south of the state of Rio Grande do Sul, Brazil where Livestock and horse-related activities are directly related to native traditions
This study was performed by analyzing results from diagnoses made by Parasitic Diseases Study Group (GEEP), at the Faculty of Veterinary Medicine, Federal University of Pelotas (UFPel), Brazil, during the years 2018 and 2019, as part of an extension project elaborated to provide scientific basis for landowners decisions regarding horse sanitary management

Summary

Introduction

In Brazil, the horse market provides financial incomes of approximately R$ 15 billion per year through a population of more than 5 million animals, being 9.2% of this amount located in Rio Grande do Sul state (RS) (Brasil, 2016). Horse management in RS is mainly extensive, wherein animals remain in pastures – natural or cultivated - often maintained with high animal. Horses are considered one of the most susceptible animals to a wide variety of gastrointestinal parasites, being able to host several species at the same time (Rehbein et al, 2013), and endoparasitosis problems which limit considerably the productive performance of these animals. The control of parasitic infections in horses is extremely important to maintain animal health. Parasitic control keeps being based on exclusive and regular use of anthelmintics mainly due to its easy application, purchase, and cost-benefit for breeders (Molento, 2005)

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