title: Benzimidazole resistance of equine strongyles: critical tests of several classes of compounds against population B strongyles from 1977 to 1981.
abstract: From 1977 to 1981, critical tests were conducted on 10 horses naturally infected with population B strongyles. Drugs tested were: oxibendazole (OBZ), 10 mg/kg of body weight (n = 1); albendazole, 10 mg/kg (n = 1); a mixture of thiabendazole (TBZ), 44 mg/kg and trichlorfon, 40 mg/kg (n = 1); a mixture of TBZ at 44 mg/kg with piperazine (PPZ) at 55 mg of base/kg (n = 1); febantel (FBT), 6 mg/kg (n = 3), 12 mg/kg (n = 1), or 24 mg/kg (n = 1); and pyrantel (PRT) pamoate, 6.6 mg of base/kg (n = 1). Large strongyles, Strongylus vulgaris (9 horses) and S edentatus (5 horses), were effectively removed (100%) by each compound and mixture. Five species of small strongyles (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus goldi, and Cylicostephanus longibursatus), previously singled out in this population as resistant to 5 benzimidazoles (TBZ, mebendazole, cambendazole, fenbendazole, and oxfendazole), but not OBZ, were efficaciously removed by OBZ, albendazole, the mixture of TBZ plus PPZ, FBT (24 mg/kg), or PRT. These 5 small strongyle species were resistant to FBT (6 mg/kg) in 3 foals and Cylicostephanus minutus was also resistant in 2 of 3 foals to FBT (6 mg/kg). Doubling the dose of FBT to 12 mg/kg increased the average removal of the 5 basic species plus Cylicostephanus minutus to 88%. The mixture of TBZ and trichlorfon was relatively ineffective against 3 species (C catinatum, C coronatum, and Cylicostephanus longibursatus), but unexpectedly efficacious (86% to 99%) for 2 species (Cylicocyclus nassatus and Cylicostephanus goldi).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D015766:Albendazole; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D001562:Benzimidazoles / Q000627:therapeutic use*; D004338:Drug Combinations; D004341:Drug Evaluation; D004351:Drug Resistance; D005260:Female; D006146:Guanidines / Q000627:therapeutic use; D006736:Horses; D008297:Male; D010270:Parasite Egg Count; D000077489:Piperazine; D010879:Piperazines / Q000627:therapeutic use; D011716:Pyrantel Pamoate / Q000627:therapeutic use; D013319:Strongyle Infections, Equine / Q000188:drug therapy* / Q000469:parasitology; D013320:Strongyloidea / Q000187:drug effects*; D013827:Thiabendazole / Q000627:therapeutic use; D014236:Trichlorfon / Q000627:therapeutic use
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D004338:Drug Combinations; D006146:Guanidines; D010879:Piperazines; C011321:oxibendazole; D000077489:Piperazine; D011716:Pyrantel Pamoate; D014236:Trichlorfon; D015766:Albendazole; D013827:Thiabendazole; C017309:febantel