Journal article
Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses
Parasites & Vectors, Vol.14(1), Art. 597
2021
Abstract
Background
Cyathostomins are the most important and common parasitic nematodes of horses, with > 50 species known to occur worldwide. The frequent and indiscriminate use of anthelmintics has resulted in the development of anthelmintic resistance (AR) in horse nematodes. In this study we assessed the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses.
Methods
Two drug efficacy trials per farm were conducted on two thoroughbred horse farms in the state of Victoria, Australia. In the first trial, the horses on Farm A were treated with single and combinations of anthelmintics, including oxfendazole (OFZ), abamectin (ABM), abamectin and morantel (ABM + MOR), moxidectin (MOX) and oxfendazole and pyrantel (OFZ + PYR), at the recommended doses, whereas the horses on Farm B only received MOX, at the recommended dose. The faecal egg count reduction test (FECRT) was used to determine the efficacy and egg reappearance period (ERP) of anthelmintics. Based on the results of the first trial, the efficacies of MOX and a combination of ABM + MOR were reassessed to confirm their activities against cyathostomins.
Results
Of the five anthelmintic products tested on Farm A, resistance against OFZ, ABM and OFZ + PYR was found, with efficacies of − 41% (− 195% lower confidence limit [LCL]), 73% (60% LCL) and 82% (66% LCL) at 2 weeks post-treatment, respectively. The FECRT showed high efficacies of MOX and ABM + MOR (100%) at 2 week post-treatment and shortened ERPs for these anthelmintics (ABM + MOR: 4 weeks; MOX: 5 weeks). Resistance to MOX was found on Farm B, with a reduced efficacy of 90% (70% LCL) and 89% (82% LCL) at 2 weeks post-treatment in trials one and two, respectively.
Conclusions
This study provides the first evidence of MOX- and multidrug-resistant (ABM and combinations of anthelmintics) cyathostomins in Australia and indicates the need for continuous surveillance of the efficacy of currently effective anthelmintics and large-scale investigations to assess the ERP for various anthelmintics.
Details
- Title
- Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses
- Authors/Creators
- G. Abbas (Author/Creator) - The University of MelbourneA. Ghafar (Author/Creator) - The University of MelbourneJ. Hurley (Author/Creator) - Swettenham StudJ. Bauquier (Author/Creator) - The University of MelbourneA. Beasley (Author/Creator) - The University of QueenslandE.J.A. Wilkes (Author/Creator) - Charles Sturt UniversityC. Jacobson (Author/Creator) - Murdoch UniversityC. El-Hage (Author/Creator) - The University of MelbourneL. Cudmore (Author/Creator) - Newmarket Equine HospitalP. Carrigan (Author/Creator) - Newmarket Equine HospitalB. Tennent-Brown (Author/Creator) - The University of MelbourneC.G. Gauci (Author/Creator) - The University of MelbourneM.K. Nielsen (Author/Creator) - University of KentuckyK.J. Hughes (Author/Creator) - Charles Sturt UniversityI. Beveridge (Author/Creator) - The University of MelbourneA. Jabbar (Author/Creator) - The University of Melbourne
- Publication Details
- Parasites & Vectors, Vol.14(1), Art. 597
- Publisher
- BioMed Central
- Identifiers
- 991005541662707891
- Copyright
- © 2021 The Authors.
- Murdoch Affiliation
- Centre for Animal Production and Health
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
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- Citation topics
- 1 Clinical & Life Sciences
- 1.163 Parasitology - General
- 1.163.1022 Anthelmintic Resistance
- Web Of Science research areas
- Parasitology
- Tropical Medicine
- ESI research areas
- Microbiology