Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast.
Abstract: Gastrointestinal nematodes (GIN) are a major impediment to breeding and exploitation of horses. Traditional control of GIN has generated resistance to main anthelmintics, including ivermectin. An analysis of five ranches with a history of IVM use was done to determine the efficacy and resistance of GIN to IVM treatment in horses from the Mexican southeast. Predesigned questionnaires were applied to collect information on previous treatment protocols. The fecal egg count reduction test (FECRT) was applied to determine resistance. Before IVM application, a McMaster test was used to diagnose GIN infection in horses, and feces cultures were done to identify L larvae for Strongylida eggs. Pre-treatment samples showed that 72.7% (80/110) of horses were GIN positive, with cyathostomins being the most frequent (91.8%), followed by Oxyuris equi (7.0%), Parascaris equorum (1.0%), and Strongylus vulgaris (0.2%). Based on the results, the horses at each ranch were divided in control (CG) and experimental (EG) groups with similar eggs per gram of feces (EPG). The EG (40/80) was dewormed with IVM (0.2 mg/kg orally) and the CG (40/80) remained untreated. After 14 days, EPG were measured, and feces cultures were done again to identify L larvae. After treatment of EG, 40% (16/40) of horses were positive, the most frequently identified GIN were cyathostomins (98.6%), followed by P. equorum (1.0%) and S. vulgaris (0.2%). Three of the five ranches were classified as resistant, according to the FECRT, with a percentage of reduction from 53 to 68%, all of which used IVM ≥4 times annually. This is the first evidence of resistance in cyathostomins to IVM treatment in horses from the Mexican southeast, adding to the current problem of anthelmintic resistance in equine GIN.
Copyright © 2023 Elsevier B.V. All rights reserved.
Publication Date: 2023-07-19 PubMed ID: 37652626DOI: 10.1016/j.vprsr.2023.100907Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study aims to analyze if the traditional drug ivermectin, used to treat gastrointestinal nematodes (GIN) or worms in horses, is still effective. It focuses on horses in the Mexican southeast, and has found evidence that these worms have developed resistance to ivermectin.
Research Context
- Gastrointestinal nematodes (GIN) are a significant concern for horse breeding as they can cause various health issues in horses. Ivermectin is a commonly used drug to manage these parasitic infections.
- However, with continued use, parasites can develop resistance to these treatments, making them ineffective. The concerning trend of anthelmintic resistance is emerging globally. This research focuses on Southeast Mexico, where ivermectin has been regularly used.
Research Methodology
- Researchers examined five different ranches known for their ivermectin use. They utilized predesigned questionnaires to collect any information related to the treatment protocols that have been formerly executed.
- To diagnose the infection, a McMaster test is used before the application of Ivermectin. In order to identify L larvae for Strongylida eggs, fecal cultures were performed. The ‘fecal egg count reduction test’ (FECRT) was used to establish resistance.
- For this study, the horses at each ranch were divided into control and experimental groups. The experimental group was treated with ivermectin, while the control group remained untreated. The number of eggs per gram of feces (EPG) in the two groups was compared before and 14 days after Ivermectin administration. FECRT was used to calculate percentage reductions.
Research Findings
- Before the ivermectin application, the test results show that 72.7% of the horses had GIN infection, with cyathostomins being the most common, followed by Oxyuris equi, Parascaris equorum, and Strongylus vulgaris.
- After the application of ivermectin, 40% of the horses in the experimental group still tested positive for GINs, suggesting the drug was not completely effective. The resistant GIN were again mainly cyathostomins.
- Three out of the five ranches studied were classified as resistant, with reduction percentages ranging from 53 to 68%. All these resistant properties were found in ranches that used Ivermectin more than four times a year.
Research Implications
- This is the first evidence of resistance in cyathostomins to Ivermectin treatment specifically in horses from the Mexican southeast.
- The study highlights the growing problem of anthelmintic resistance, indicating that alternative treatments or management strategies may be required in the future to effectively control these parasitic infections in horses.
Cite This Article
APA
Flota-Burgos GJ, Rosado-Aguilar JA, Rojas-Becerril R, Rodru00edguez-Vivas RI, Trinidad-Martu00ednez I.
(2023).
Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast.
Vet Parasitol Reg Stud Reports, 44, 100907.
https://doi.org/10.1016/j.vprsr.2023.100907 Publication
Researcher Affiliations
- Departamento de salud animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autu00f3noma de Yucatu00e1n, Km. 15.5 carretera Mu00e9rida-Xmatkuil, CP 97100 Mu00e9rida, Yucatu00e1n, Mexico.
- Departamento de salud animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autu00f3noma de Yucatu00e1n, Km. 15.5 carretera Mu00e9rida-Xmatkuil, CP 97100 Mu00e9rida, Yucatu00e1n, Mexico. Electronic address: ja.rosado@correo.uady.mx.
- Asociaciu00f3n Mexicana de Mu00e9dicos Veterinarios Especialistas en Equinos A.C., Calzada Mu00e9xico Tacuba # 213, esquina Maestro Rural, Col. Un lugar para nosotros, Del. Miguel Hidalgo CP 11330, D.F, Mexico.
- Departamento de salud animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autu00f3noma de Yucatu00e1n, Km. 15.5 carretera Mu00e9rida-Xmatkuil, CP 97100 Mu00e9rida, Yucatu00e1n, Mexico.
- Departamento de salud animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autu00f3noma de Yucatu00e1n, Km. 15.5 carretera Mu00e9rida-Xmatkuil, CP 97100 Mu00e9rida, Yucatu00e1n, Mexico.
MeSH Terms
- Animals
- Horses
- Ivermectin / pharmacology
- Ivermectin / therapeutic use
- Feces
- Ascaridoidea
- Larva
- Strongylida
Conflict of Interest Statement
Declaration of Competing Interest None.