title: Anthelmintic resistance in ovine gastrointestinal nematodes in inland southern Queensland.
abstract: OBJECTIVE
  To establish the prevalence of anthelmintic resistance in ovine gastrointestinal nematodes in southern Queensland.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  This level of anthelmintic resistance in southern Queensland will severely compromise worm control and force increased use of monepantel.
authors.affiliation: Department of Agriculture, Fisheries and Forestry, Eco-Sciences Precinct, Dutton Park, Brisbane, Queensland, 4102, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Lyndal-Murphy
authors.forename: W K
authors.initials: WK
authors.lastname: Ehrlich
authors.forename: D G
authors.initials: DG
authors.lastname: Mayer
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000187:drug effects*; D009348:Nematoda / Q000187:drug effects*; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D011793:Queensland; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*; D011795:Surveys and Questionnaires
chemical_list: D000871:Anthelmintics
keywords: Haemonchus contortus; anthelmintic resistance; faecal egg count reduction test; nematode control; sheep