A survey of macrocyclic lactone efficacy in Australian cyathostomin populations

Beasley, A. M. and Kotze, A. C. and Allen, K. and Coleman, G. T. (2017) A survey of macrocyclic lactone efficacy in Australian cyathostomin populations. Veterinary Parasitology: Regional Studies and Reports, 8. pp. 127-132.


The macrocyclic lactone (ML) drugs are central to the control of equine strongyles but recent international reports raise concerns about reduced efficacy of these drugs against cyathostomins. The objectives of the present study were firstly, to evaluate the efficacy of ML drugs against cyathostomins on a cross-section of Australian horse farms, and secondly, to determine the egg reappearance period (ERP) following treatment of horses with MLs. A total of 419 horses on 43 properties were treated orally with ivermectin, abamectin or moxidectin, at recommended dose rates and drug efficacy was determined using the faecal egg count reduction test. Efficacy of 100% at 14 days post-treatment was reported on all of the 43 farms. ERP following ivermectin treatment was 6 weeks on two properties and ERP following moxidectin treatment was 12 weeks on a third property. These ERPs are shorter than those reported at the time of commercial release of these drugs which likely reflects changing drug susceptibility of the cyathostomin populations tested. Ongoing surveillance of drug efficacy and ERPs should be part of an integrated management approach to equine worm control that prioritises the preservation of anthelmintic efficacy.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: No
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 29 Nov 2017 01:17
Last Modified: 04 Aug 2022 23:03
Uncontrolled Keywords: cyathostomins; egg reappearance period; ivermectin; macrocyclic lactones; resistance; strongyles; clinical and experimental pharmacology
Fields of Research (2008): 07 Agricultural and Veterinary Sciences > 0707 Veterinary Sciences > 070708 Veterinary Parasitology
Fields of Research (2020): 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3009 Veterinary sciences > 300909 Veterinary parasitology
Identification Number or DOI: https://doi.org/10.1016/j.vprsr.2017.03.009
URI: http://eprints.usq.edu.au/id/eprint/33367

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