Larval development assay for detection of anthelmintic resistance in cyathostomins of Swedish horses.
Abstract: The aim of this study was to investigate the suitability of a larval development assay (LDA) for the determination of anthelmintic resistance in cyathostomin nematode populations of the horse. In addition, comparison of results between geographic regions, types of horse establishment, and the use of anthelmintics in Sweden, was established. Seventy horse herds from different parts of Sweden were sampled, and strongyle eggs from the faeces of 54 of those were investigated by an LDA (DrenchRite). The following anthelmintics were tested: thiabendazole (TBZ), levamisole (LEV), ivermectin monosaccharide (IVM-MS), ivermectin aglycone (IVM-AG) and pyrantel (PYR). The LC50 values for TBZ and LEV were generally lower than those previously reported in other LDA studies on horse nematodes. This could be related to the infrequent use of these compounds for the past 20 years in Sweden. In this study, there was a great variation within and between assay plates that could not be explained. Still the LC50 values differed significantly between the regions for all anthelmintics, except for pyrantel. The highest LC50s were observed in parasite populations from the south of Sweden. There were no significant differences between riding schools and studs. Limitations of this technique exist, namely the lack of established cut-off values for susceptible and resistant populations and interpretation problems related to multi-species infections. Although there are advantages with LDA such as the possibility of testing several compounds simultaneously without interference with the deworming programmes on the farms, we conclude that LDA currently is not a reliable alternative to the faecal egg count reduction test (FECRT).
Publication Date: 2005-03-03 PubMed ID: 15740863DOI: 10.1016/j.vetpar.2004.11.029Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research was aimed at investigating the effectiveness of a Larval Development Assay (LDA) in identifying drug resistance in a specific type of horse parasite, cyathostomins, in Sweden. Despite varying results, the study concluded that the LDA cannot reliably replace the standard Faecal Egg Count Reduction Test (FECRT).
Larval Development Assay (LDA)
- The study was designed to test the suitability of an LDA for detecting anthelmintic resistance in cyathostomin nematode populations in horses.
- Anthelmintics are medicines used to rid an organism of parasitic worms, and their effectiveness was examined through this assay.
Anthelmintics Tested
- Various anthelmintics, including thiabendazole (TBZ), levamisole (LEV), ivermectin monosaccharide (IVM-MS), ivermectin aglycone (IVM-AG), and pyrantel (PYR), were tested on horse samples from 70 herds across Sweden.
- General observation showed lower general Lethal Concentration 50 (LC50) values for TBZ and LEV, possibly due to their infrequent use over the past 20 years in Sweden.
Geographic and Establishment Analysis
- The study compared results from different geographic regions in Sweden and various horse establishments (like riding schools and studs).
- In spite of several inconsistencies and variations in the test results, the LC50 values significantly differed between regions for all anthelmintics, except for pyrantel.
- The study found the highest LC50 values in parasite populations from the south of Sweden, however, there was no significant difference between various types of horse establishments studied.
Limitations and Conclusion
- There were limitations to the LDA such as lack of clear cut-off values for susceptible and resistant populations and the difficulty of interpreting cases involving multi-species infections.
- Even though LDA has certain benefits, such as allowing the testing of several compounds simultaneously without interfering with on-farm deworming programs, the study concluded that it is currently not a reliable replacement for the FECRT.
Cite This Article
APA
Lind EO, Uggla A, Waller P, Höglund J.
(2005).
Larval development assay for detection of anthelmintic resistance in cyathostomins of Swedish horses.
Vet Parasitol, 128(3-4), 261-269.
https://doi.org/10.1016/j.vetpar.2004.11.029 Publication
Researcher Affiliations
- Department of Parasitology (SWEPAR), Swedish University of Agricultural Sciences and National Veterinary Institute, SE-751 89 Uppsala, Sweden. eva.osterman.lind@bvf.slu.se
MeSH Terms
- Animals
- Anthelmintics / pharmacology
- Drug Resistance
- Feces / parasitology
- Horse Diseases / drug therapy
- Horse Diseases / parasitology
- Horses
- Larva / drug effects
- Larva / growth & development
- Male
- Parasite Egg Count / veterinary
- Statistics, Nonparametric
- Strongyle Infections, Equine / drug therapy
- Strongyle Infections, Equine / parasitology
- Strongylus / drug effects
- Strongylus / growth & development
- Strongylus / isolation & purification
- Surveys and Questionnaires
- Sweden
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