Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Ghazanfar Abbas; Abdul Ghafar; John Hurley; Jenni Bauquier; Anne Beasley; Edwina J.A. Wilkes; Caroline Jacobson; Charles El-Hage; Lucy Cudmore; Peter Carrigan; Brett Tennent-Brown; Charles G. Gauci; Martin K. Nielsen; Kristopher J. Hughes; Ian Beveridge; Abdul Jabbar

doi:10.1186/s13071-021-05103-8

Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Ghazanfar Abbas, Abdul Ghafar, John Hurley, Jenni Bauquier, Anne Beasley, Edwina J.A. Wilkes, Caroline Jacobson, Charles El-Hage, Lucy Cudmore, Peter Carrigan, Brett Tennent-Brown, Charles G. Gauci, Martin K. Nielsen, Kristopher J. Hughes, Ian Beveridge, Abdul Jabbar

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

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. Graphical Abstract: [Figure not available: see fulltext.]

Original language	English
Article number	597
Journal	Parasites and Vectors
Volume	14
Issue number	1
DOIs	https://doi.org/10.1186/s13071-021-05103-8
State	Published - Dec 2021

Bibliographical note

Publisher Copyright:
© 2021, The Author(s).

Funding

The financial assistance for this project was provided by AgriFutures Australia, Thoroughbred Breeders Australia and Boehringer Ingelheim, Australia. Boehringer Ingelheim did not have any role in the design or content of this manuscript. GA is a grateful recipient of the Australian Government Research Training Scholarship through the University of Melbourne.

Funders	Funder number
Thoroughbred Breeders Australia
Boehringer-Ingelheim
The University of Melbourne
Agrifutures Australia

Keywords

Australian thoroughbred horses
Cyathostomins
Egg reappearance period
FECRT
Moxidectin
Resistance

ASJC Scopus subject areas

Infectious Diseases
General Veterinary
Parasitology

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1186/s13071-021-05103-8

Cite this

Abbas, G., Ghafar, A., Hurley, J., Bauquier, J., Beasley, A., Wilkes, E. J. A., Jacobson, C., El-Hage, C., Cudmore, L., Carrigan, P., Tennent-Brown, B., Gauci, C. G., Nielsen, M. K., Hughes, K. J., Beveridge, I., & Jabbar, A. (2021). Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses. Parasites and Vectors, 14(1), Article 597. https://doi.org/10.1186/s13071-021-05103-8

@article{f1bf33f872564b8a8fdfa3950a3e42ac,

title = "Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses",

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. Graphical Abstract: [Figure not available: see fulltext.]",

keywords = "Australian thoroughbred horses, Cyathostomins, Egg reappearance period, FECRT, Moxidectin, Resistance",

author = "Ghazanfar Abbas and Abdul Ghafar and John Hurley and Jenni Bauquier and Anne Beasley and Wilkes, \{Edwina J.A.\} and Caroline Jacobson and Charles El-Hage and Lucy Cudmore and Peter Carrigan and Brett Tennent-Brown and Gauci, \{Charles G.\} and Nielsen, \{Martin K.\} and Hughes, \{Kristopher J.\} and Ian Beveridge and Abdul Jabbar",

note = "Publisher Copyright: {\textcopyright} 2021, The Author(s).",

year = "2021",

month = dec,

doi = "10.1186/s13071-021-05103-8",

language = "English",

volume = "14",

number = "1",

}

Abbas, G, Ghafar, A, Hurley, J, Bauquier, J, Beasley, A, Wilkes, EJA, Jacobson, C, El-Hage, C, Cudmore, L, Carrigan, P, Tennent-Brown, B, Gauci, CG, Nielsen, MK, Hughes, KJ, Beveridge, I & Jabbar, A 2021, 'Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses', Parasites and Vectors, vol. 14, no. 1, 597. https://doi.org/10.1186/s13071-021-05103-8

TY - JOUR

T1 - Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

AU - Abbas, Ghazanfar

AU - Ghafar, Abdul

AU - Hurley, John

AU - Bauquier, Jenni

AU - Beasley, Anne

AU - Wilkes, Edwina J.A.

AU - Jacobson, Caroline

AU - El-Hage, Charles

AU - Cudmore, Lucy

AU - Carrigan, Peter

AU - Tennent-Brown, Brett

AU - Gauci, Charles G.

AU - Nielsen, Martin K.

AU - Hughes, Kristopher J.

AU - Beveridge, Ian

AU - Jabbar, Abdul

PY - 2021/12

Y1 - 2021/12

N2 - 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. Graphical Abstract: [Figure not available: see fulltext.]

AB - 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. Graphical Abstract: [Figure not available: see fulltext.]

KW - Australian thoroughbred horses

KW - Cyathostomins

KW - Egg reappearance period

KW - FECRT

KW - Moxidectin

KW - Resistance

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U2 - 10.1186/s13071-021-05103-8

DO - 10.1186/s13071-021-05103-8

M3 - Article

C2 - 34863271

AN - SCOPUS:85120735095

SN - 1756-3305

VL - 14

JO - Parasites and Vectors

JF - Parasites and Vectors

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M1 - 597

ER -

Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

UN SDGs

Access to Document

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