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Anthelmintic resistance in ovine gastrointestinal nematodes in inland southern Queensland

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Lyndal-Murphy, M., Ehrlich, W. K. and Mayer, D. G. (2014) Anthelmintic resistance in ovine gastrointestinal nematodes in inland southern Queensland. Australian Veterinary Journal, 92 (11). pp. 415-420. ISSN 1751-0813


Article Link: http://dx.doi.org/10.1111/avj.12250


Objective To establish the prevalence of anthelmintic resistance in ovine gastrointestinal nematodes in southern Queensland. Design An observational parasitological study using the faecal egg count reduction test. Methods Sheep farms (n = 20) enrolled in this study met the twin criteria of using worm testing for drench decisions and having concerns about anthelmintic efficacy. On each farm, 105 sheep were randomly allocated to one of six treatment groups or an untreated control group. Faecal samples were collected on day 0 and days 10–14 for worm egg counts and larval differentiation. Single- and multi-combination anthelmintics, persistent and non-persistent, oral liquid or capsule, pour-on and injectable formulations were tested. Monepantel was not tested. Farmers also responded to a questionnaire on drenching practices. Results Haemonchus contortus was the predominant species. Efficacy <95% was recorded on 85% of farms for one or more anthelmintics and on 10% of farms for six anthelmintics. No resistance was identified on three farms. The 4-way combination product was efficacious (n = 4 farms). Napthalophos resistance was detected on one farm only. Resistance to levamisole (42% of farms), moxidectin injection (50% of farms) and the closantel/abamectin combination (67% of farms) was identified. Moxidectin oral was efficacious against Trichostrongylus colubriformis, which was predominant on only one farm. Of the farms tested, 55% ran meat breeds, 60% dosed more than the recommended dose rate and 70% always, mostly or when possible practised a ‘drench and move’ strategy. Conclusion This level of anthelmintic resistance in southern Queensland will severely compromise worm control and force increased use of monepantel.

Item Type:Article
Business groups:Animal Science
Keywords:anthelmintic resistance faecal egg count reduction test Haemonchus contortus nematode control sheep
Subjects:Veterinary medicine > Communicable diseases of animals (General)
Animal culture > Sheep
Live Archive:21 Jan 2015 05:54
Last Modified:03 Sep 2021 16:50

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