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An investigation of anthelmintic efficacy against strongyles on equine yards in S cotland
Author(s) -
Stratford C. H.,
Lester H. E.,
Pickles K. J.,
McGorum B. C.,
Matthews J. B.
Publication year - 2014
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12079
Subject(s) - moxidectin , fenbendazole , ivermectin , anthelmintic , pyrantel , veterinary medicine , eggs per gram , biology , zoology , feces , medicine , ecology
Summary Reasons for performing study Cyathostomins comprise 50 helminth species, considered the most problematic equine endoparasites. Three classes of anthelmintic are currently licensed for their control, namely the benzimidazoles (fenbendazole), tetrahydropyrimidines (pyrantel) and macrocyclic lactones (ivermectin and moxidectin). Anthelmintic resistance in cyathostomins is common. With no new classes expected in the near future, it is essential to determine the efficacy of the available anthelmintics to inform future control programmes. Objectives To determine the efficacy of all 3 anthelmintic classes against strongyles in equids on livery yards in east and central S cotland. Study design Anthelmintic efficacy testing using the faecal egg count reduction test (FECRT).Methods FECRT s were performed on equids with initial strongyle faecal egg counts ( FEC s) of ≥50 eggs per gram. Efficacy was determined by comparing pretreatment (Day 0) and 14 days post treatment (Day 14) FEC s. The following chemicals were tested: fenbendazole, pyrantel, ivermectin and moxidectin. Group arithmetic mean FECR of >90% for fenbendazole and pyrantel, and >95% for ivermectin and moxidectin, represented efficacy, whereas lower mean FECR indicated potential resistance. Results A total of 447 FECRT s were performed on 15 yards, as follows (the numbers in parentheses represent the number of yards each anthelmintic was tested on): 55 equids (7 yards) fenbendazole, 111 (8 yards) pyrantel, 163 (13 yards) ivermectin and 118 (10 yards) moxidectin. Fenbendazole resistance was documented on all yards (range of mean FECR , 15.8–83.4%), whereas pyrantel (90.4–99.6%), ivermectin (99.5–100%) and moxidectin (99.4–100%) treatment had acceptable efficacy. Conclusions Reduced efficacy of fenbendazole was widespread, whereas >90% efficacy was found after pyrantel, and >95% efficacy after ivermectin and moxidectin. Overall, efficacies were higher than reported previously in E urope and the USA , potentially reflecting differences in management and anthelmintic use on the yards surveyed. Potential relevance The use of fenbendazole for strongyle control in S cotland should be questioned. Targeted use of pyrantel should be encouraged to reduce reliance on macrocyclic lactones. Further work to correlate management practices with the presence of anthelmintic resistance is warranted. The S ummary is available in C hinese – see S upporting information.